For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/
MAX8895X/MAX8895Y
EVALUATION KIT AVAILABLE
19-5205; Rev 4 9/12
Ordering Information and Typical Operating Circuit appear
at end of data sheet.
General Description
The MAX8895_ USB-compliant linear battery chargers
operate from either a USB port or dedicated charger with
automatic detection of adapter type and USB enumera-
tion capability. The MAX8895_ integrate the battery dis-
connect switch, current-sense circuit, MOSFET pass ele-
ments, and thermal regulation circuitry, and eliminate the
external reverse-blocking Schottky diode to create the
simplest and smallest stand-alone charging solutions.
The MAX8895_ includes an automated detection of
charge adapter type, making it possible to distinguish
between USB 2.0 device, USB charger, and dedicated
charger devices. Furthermore, the MAX8895_ include a
USB enumeration function that automatically negotiates
with a USB host, making it possible to achieve the highest
current available from a USB 2.0 device or USB charger
without processor intervention. The adapter type detec-
tion is compliant with USB 2.0 specification as well as USB
charging Revision 1.1.
The MAX8895_ controls the charging sequence for single-
cell Li+ batteries from initial power-OK indication, through
prequalification, fast-charge, top-off, and finally charge
termination. Charging is controlled using constant cur-
rent, constant voltage, and constant die-temperature
(CCCVCTj) regulation for safe operation under all condi-
tions. The maximum charging current is adaptively con-
trolled by subtracting the system current from the input
current limit, ensuring that the charging current is always
maximized for any given operating condition.
The MAX8895_ features optimized smart power control
to make the best use of limited USB or adapter power.
Battery charge current is set independently of the
SYS_ input current limit. Power not used by the system
charges the battery. Automatic input selection switches
the system from battery to external power. This allows
the application to operate without a battery, discharged
battery, or dead battery.
Other features include undervoltage lockout (UVLO),
overvoltage protection (OVP), charge status flag, charge
fault flag, power-OK monitor, battery thermistor monitor,
charge timer, and a 3.3V output.
The MAX8895_ operates from a +4.0V to +6.6V sup-
ply and include overvoltage protection up to +16V. The
MAX8895_ is specified over the extended temperature
range (-40NC to +85NC) and are available in a compact
2.36mm x 2.36mm, 25-bump WLP package (0.4mm pitch).
Features
S Enables Charging from a USB Port*
S Automatic Detection of Adapter Type
S Enumeration Capability Without Processor
Intervention
S USB Low-Speed Operation Without External
Crystal (MAX8895V/MAX8895W/MAX8895X)
S USB Full-Speed Operation Using an External
Crystal (MAX8895Y)
S Compliant with USB 2.0 Specification
S Compliant with USB Charging Specification
(Revision 1.1)
S Adaptive Input Current Limit for Dedicated
Charger
S Input Overvoltage Protection to 16V
S Automatic Current Sharing Between Battery
Charging and System
S Smart Power SelectorK Allows Operation with
Discharged or No Battery
S NTC Monitoring of Battery Temperature
S No External MOSFETs Required
S Thermal Regulation Prevents Overheating
S 2µA Shutdown Current
S Tiny 2.36mm x 2.36mm, 25-Bump, 0.4mm Pitch
WLP Package
Applications
Bluetooth® Headsets
Charging Cradles
Portable Devices
Smart Power Selector is a trademark of Maxim Integrated
Products, Inc.
*Protected by US Patent #6,507,172.
Bluetooth is a registered trademark of Bluetooth SIG.
2 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
BUS_ to AGND ...................................................-0.3V to +16.0V
XIN, XOUT, INT_3V3 to AGND ............................. -0.3V to +4.0V
ENU_EN, SUS_EN, RWU, D+, D-, PREQ, CHG, UOK,
FLT, BAT_, SYS_, CEN, STDBY, DET_DONE,
IBUS_DEF, CHG_TYPE to AGND ..................... -0.3V to +6.0V
KB_TM, ISET, THM, IDN,
CT to AGND ................................... -0.3V to (VINT_3V3 + 0.3V)
DGND to AGND ..................................................-0.3V to + 0.3V
IBUS_, IBAT_, and ISYS_ Continuous Current ........... 1800mARMS
Continuous Power Dissipation (TA = +70NC)
25-Bump, 2.36mm x 2.36mm WLP
(derate 19.34mW/NC above +70NC) ..........................1560mW
Operating Temperature ...................................... -40NC to +85NC
Junction Temperature .....................................................+150NC
Storage Temperature Range ............................ -65NC to +150NC
Soldering Temperature (reflow) ......................................+260NC
ELECTRICAL CHARACTERISTICS
(THM = CEN = SUS_EN = AGND, VBAT_ = 4.2V, VBUS_, CT, PREQ, CHG, UOK, FLT, DET_DONE are unconnected, TA = -40NC to
+85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 1)
ABSOLUTE MAXIMUM RATINGS
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
USB-TO-SYS PREREGULATOR
USB Operating Range Initial VBUS_ voltage before enabling charger 4.0 6.6 V
USB Standoff Voltage VBAT_ = VSYS_ = 0V, IBUS_ < 650FA (max) 14 V
BUS_OK Debounce Timer tUSB_DB Time from BUS_ within valid range until UOK
logic-low 500 650 ms
USB Undervoltage Lockout
Threshold
UOK logic-low,
VBUS_ rising,
100mV hysteresis
Before initial detection of
external device 3.85 4.0 4.15
V
UOK logic-low,
VBUS_ falling
USB 2.0 low-power
device 3.75 3.9 4.05
UOK logic-low,
VBUS_ falling
USB 2.0 high-power
device 3.95 4.1 4.25
UOK logic-low,
VBUS_ falling
Dedicated charger or
USB charger
VSYS _
- 100mV
VSYS_
+ 50mV
VSYS_
+ 200mV
USB Overvoltage Protection
Threshold
UOK logic-low, VBUS_ rising, 100mV
hysteresis 6.8 6.95 7.1 V
USB Input Supply Current
(Note 2)
IDETECT
Charge type detection,
ISYS_ = IBAT_ = 0mA,
VCEN = 0V
MAX8895V/
MAX8895W/
MAX8895X
0.5
mA
MAX8895Y 2.5
IENUMERATE USB 2.0 enumeration in progress,
ISYS_ = IBAT_ = 0mA, VCEN = 0V 100
ISUSPEND Suspend mode, ISYS_ = IBAT_ =
0mA, VSTDBY = 3.3V
MAX8895V/
MAX8895W/
MAX8895X
0.5
MAX8895Y 2.5
IUSB_100mA USB 2.0 low-power
device detected
TA = 0NC to +85NC100
TA = -40NC to +85NC102.5
IUSB_500mA USB 2.0 high-power device detected 500
USB Input Current Limit
ISUS During suspend 0
mA
IENU During USB enumeration 40 45 55
IUSB_LP USB 2.0 low-power device detected 80 90 98
IUSB_HP USB 2.0 high-power device detected 460 475 490
3Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
ELECTRICAL CHARACTERISTICS (continued)
(THM = CEN = SUS_EN = AGND, VBAT_ = 4.2V, VBUS_, CT, PREQ, CHG, UOK, FLT, DET_DONE are unconnected, TA = -40NC to
+85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
VBUS_-to-VSYS_ On-
Resistance VBUS_ = VCEN = 5V, ISYS_ = 400mA 200 320 mI
VSYS_-to-VBAT_ Reverse
Regulation
When SYS is in regulation and charging
stops, VSYS_ falling, 50mV hysteresis
VBAT_
- 80mV
VBAT_
- 50mV
VBAT_
- 20mV V
Input Limiter Soft-Start Time Input current ramp time 50 100 Fs
Thermal-Limit Start
Temperature TDIE_LIM +110 NC
Thermal-Limit Start
Temperature Hysteresis 10 NC
Thermal-Limit Gain ISYS_ reduction/die temperature (above +110NC) 5%/NC
VBUS_ Adaptive Current
Regulation Threshold
VBUS_ regulation threshold where input
current limit is regulated for dedicated
charger or USB charger
VSYS_ +
440mV
VSYS_ +
550mV V
SYS_ Regulation Voltage VBAT_ > 3.45V, ISYS_ = 1mA to 1.6A,
VBUS_ = VCEN = 5V
VBAT_ +
140mV
VBAT_ +
210mV V
Minimum SYS Regulation
Voltage
VBUS_ = 6V, ISYS_ = 1mA to 1.6A,
VCEN = 5V 3.3 3.4 3.55 V
CHARGER
BAT_-to-SYS_ On-Resistance ISYS_ = 200mA 55 80 mI
BAT_ Undervoltage Lockout VBAT_UVLO_F VBAT_ falling 2.60 2.85 3.1 V
VBAT_UVLO_R VBAT_ rising 2.75 3.00 3.25
Charger Soft-Start Time Charge-current ramp time 1 ms
BAT_ Leakage Current VBUS_ not connected 2 6 FA
VBUS_ connected, VCEN = 5V 2 6
PRECHARGE MODE
BAT_ Precharge-Current
Set Range IPCHG RISET = 30kI to 1.875kI, VBAT_ >1.4V
(Note 3) IFCHG/10 A
BAT_ Prequalification
Threshold
VBAT_PCHG_R VBAT_ rising 2.7 2.8 2.9 V
VBAT_PCHG_F VBAT_ falling 2.6 2.7 2.8
FAST-CHARGE MODE
BAT_ Charge-Current Set
Range IFCHG
RISET = 30kI to 1.875kI, VBAT_ >1.4V
(Note 3) 0.1 1.85 A
ISET = INT_3V3 (Note 3) 600 mA
BAT_ Charge-Current
Accuracy, Charger Loop in
Control
VBUS_ = 5.5V
(Note 3)
RISET = 1.875kI0000 1850 0000
mA
RISET = 5kI540 600 660
RISET = 30kI90 100 110
BAT_ Fast-Charge Threshold
VBAT_FCHG_R VBAT_ rising threshold, where charging
current IFCHG is reduced to ITCHG 3.9 4.0 4.1
V
VBAT_FCHG_F VBAT_ falling threshold, where charging
current is increased to IFCHG 3.7 3.8 3.9
4 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
ELECTRICAL CHARACTERISTICS (continued)
(THM = CEN = SUS_EN = AGND, VBAT_ = 4.2V, VBUS_, CT, PREQ, CHG, UOK, FLT, DET_DONE are unconnected, TA = -40NC to
+85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
TOP-OFF CHARGE MODE
Top-Off Charge Current ITCHG RISET = 30kI to 1.875kI (Note 3) 0.6 x
IFCHG A
BAT_ Charge Termination
Current Range ICHG_DONE RIDN = 240kI to 15kI10 160 mA
IDN = INT_3V3 80
BAT_ Regulation Voltage VBAT_REG IBAT_ = 0mA TA = +25NC4.179 4.200 4.221 V
TA = 0NC to +85NC4.158 4.200 4.242
BAT_ Recharge Threshold VBAT_RECHG Recharge threshold in relation to VBAT_ in DONE
state going into top-off mode (Figure 20) -100 -200 -300 mV
CHARGE TIMER
Maximum Prequalification
Time tPCHG
From VCEN falling to
end of prequalification
charge mode,
VBAT_ = 2.5V
CT = 0.068FF16
Min
CT = AGND 20
Maximum Fast-Charge Time tFCHG From VCEN falling to
VFLT falling
CT = 0.068FF100 Min
CT = AGND 120
Maintain-Charge Time tMTCHG
CT = 0.068FF4Min
CT = AGND 5
Timer Accuracy CT = 0.068FF-30 +30 %
CT connected to AGND -30 +30
Timer Extend Threshold Percentage of charge current below which
timer clock operates at half speed 50 %
Timer Suspend Threshold Percentage of charge current below which
timer clock pauses 20 %
ADAPTER TYPE DETECTION
D- Current Sink IDM_SINK MAX8895V/MAX8895X/MAX8895Y 50 86 150 FA
MAX8895W 64 86 102
D+ Source Voltage VDP_SRC IDP_SRC = 0 to 200FA0.5 0.6 0.7 V
D+ Detection Threshold VDAT_REF 0.25 0.32 0.40 V
D+ Source On-Time tDP_SRC_ON 100 ms
D+ Source to High Current Time tDP_SRC_HC 40 ms
D- Pullup Resistor RDM_PU MAX8895V/MAX8895W/MAX8895X only,
external series resistor = 33I1.425 1.500 1.575 kI
D+ Pullup Resistor RDP_PU MAX8895Y only, external series resistor =
33I1.425 1.500 1.575 kI
D+ Charger Detection
Pullup Resistor RDP_CD_PU RDP_CD_PU connect to INT_3V3 200 330 600 kI
D- Weak Current Sink IDM_CD_PD 0.1 FA
D- Logic-High Threshold VDM_IH 0.8 2.0 V
5Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
ELECTRICAL CHARACTERISTICS (continued)
(THM = CEN = SUS_EN = AGND, VBAT_ = 4.2V, VBUS_, CT, PREQ, CHG, UOK, FLT, DET_DONE are unconnected, TA = -40NC to
+85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Enumeration Time Limit tENUM
Time from start of enumeration process
until enumeration must be completed; if
not completed, the MAX8895_ retries to
enumerate
10 s
Reconnect Timer tFAULT Time from failed enumeration to adapter type
detection reenabled 3 s
Enumeration Fail to Reconnect
Timer tENU_FAULT
Time from enumeration fail at 500mA until
enumeration is retried at 100mA or time from
enumeration fail at 100mA until reconnect
timer is started
87 ms
Reenumeration Timer tRE_ENUM
Time from when the MAX8895_ has entered
suspend mode until it reenumerates,
RWU = AGND
100 ms
Oscillator Frequency
Accuracy
MAX8895V/MAX8895X only (internal
oscillator), TA = +25NC5.91 6.00 6.09 MHz
XIN Input Current MAX8895Y only, VXIN = VSTDBY = 3.3V 10 FA
XIN Logic-High Input Voltage MAX8895Y only 2/3x
VINT_3V3 VINT_3V3 V
XIN Logic-Low Input Voltage MAX8895Y only 0.4 V
THM
THM Cold Threshold TAMB_COLD When charging is suspended, rising
threshold, 2% hysteresis 72 74 76 % of
VINT_3V3
THM Hot Threshold TAMB_HOT When charging is suspended, falling
threshold, 2% hysteresis 26 28 30 % of
VINT_3V3
THM Threshold, Disabled When THM function is disabled, falling
threshold, 2% hysteresis 3% of
VINT_3V3
THM Input Leakage THM = AGND or
INT_3V3
TA = +25NC-0.1 0.001 +0.2 FA
TA = +85NC0.01
LOGIC I/O: CHG, FLT, UOK, CEN, PREQ, KB_TM, RWU, STDBY, SUS_EN, ENU_EN, DET_DONE, CHG_TYPE, IBUS_DEF
Logic-Input Threshold
High level 1.3 V
Low level 0.4
Hysteresis 50 mV
Logic-Input Leakage Current VBUS_ = 0 to 5.5V TA = +25NC0.001 1 FA
TA = +85NC0.01
Logic-Low Output Voltage
(CHG, FLT, UOK, PREQ,
DET_DONE, CHG_TYPE Only)
Sinking 10mA 35 100 mV
Logic-High Output-Leakage
Current (CHG, FLT, UOK,
PREQ, DET_DONE, CHG_
TYPE Only)
VSYS_ = 5.5V
TA = +25NC0.001 1
FA
TA = +85NC0.01
6 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Note 1: Specifications are 100% production tested at TA = +25NC. Limits over the operating temperature range are guaranteed by
design and characterization.
Note 2: Sum of input current limit and current used for INT_3V3.
Note 3: Maximum charging current is adaptively regulated to IIN_LIM - ISYS_ with a maximum value of ICHG.
Note 4: All devices are 100% production tested at TA = +25NC. Limits over the operating temperature range are guaranteed by design.
Note 5: Guaranteed by design, not production tested.
ELECTRICAL CHARACTERISTICS (continued)
(THM = CEN = SUS_EN = AGND, VBAT_ = 4.2V, VBUS_, CT, PREQ, CHG, UOK, FLT, DET_DONE are unconnected, TA = -40NC to
+85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
USB DATA INTERFACE
Differential-Receiver Input
Sensitivity |VD+ - VD-| 0.2 V
Differential-Receiver
Common-Mode Voltage 0.8 2.5 V
D+, D- Input Impedance 300 kI
D+, D- Output Low Voltage VOL RLOAD = 1.5kI from VD- to 3.6V 0.3 V
D+, D- Output High Voltage VOH RLOAD = 15kI from D+ and D- to AGND 2.8 3.6 V
Driver Output Impedance Excludes external resistor 2 7 11 I
BUS_ Idle Time tIDLE
Only valid when an adapter type is detected
as a USB 2.0 device; time BUS_ is inactive
until charging current is reduced to ISUSPEND
3 ms
USB Host Remote Wake-Up
Timer tRWU
Time delay from when the MAX8895_ is put
into suspend mode until they request the host
for a remote wake-up
100 ms
D+, D- Rise Time
(Note 5) tRISE
MAX8895V/MAX8895W/MAX8895X only, CL =
50pF to 600pF, (Figures 5 and 6) 75 250 ns
MAX8895Y only, CL = 50pF (Figures 5 and 6) 4 20
D+, D- Fall Time
(Note 5) tFALL
MAX8895V/MAX8895W/MAX8895X only, CL =
50pF to 600pF (Figures 5 and 6) 75 250
ns
MAX8895Y only, CL = 50pF
(Figures 5 and 6) 4 20
Rise-/Fall-Time Matching
(Note 5)
MAX8895V/MAX8895W/MAX8895X only, CL =
50pF to 600pF (Figures 5 and 6) 80 120
%
MAX8895Y only, CL = 50pF
(Figures 5 and 6) 90 110
Output-Signal Crossover
Voltage (Note 5)
MAX8895V/MAX8895W/MAX8895X only, CL =
50pF to 600pF (Figures 5 and 6) 1.3 2.0
V
MAX8895Y only, CL = 50pF
(Figures 5 and 6) 1.3 2.0
INT_3V3 REGULATOR
INT_3V3 Voltage VBUS_= 5V, IINT_3V3 = 0 to 10mA 3.0 3.3 3.6 V
ESD PROTECTION (D+, D-, VBUS_)
Human Body Model VBUS_ bypassed with 1FF to AGND Q8kV
7Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Typical Operating Characteristics
(VBAT_ = 4.2V, VBUS_ = 5V, ISET = IDN = CT = SUS_EN = INT_3V3, STDBY = ENU_EN = RWU = CEN = KB_TM = AGND, circuits
of Figures 4 and 5 (MAX8895V/MAX8895X and MAX8895Y, respectively), TA = +25NC, unless otherwise noted.)
MAX8895V/W/X VBUS_ INPUT SUPPLY
CURRENT vs. VBUS_ (SUSPEND MODE)
MAX8895W/X/Y toc01
VBUS_ (V)
INPUT SUPPLY CURRENT (µA)
14122 4 6 8 10
50
100
150
200
250
300
350
400
0
01
6
SUS_EN = ENU_EN = CEN = AGND
STDBY = INT_3V3
MAX8895Y VBUS_ INPUT SUPPLY
CURRENT vs. VBUS_ (SUSPEND MODE)
MAX8895W/X/Y toc04
VBUS_ (V)
INPUT SUPPLY CURRENT (µA)
14128 104 62
50
100
150
200
250
300
350
400
450
500
0
01
6
CEN = STDBY = AGND
MAX8895V/W/X VBUS_ INPUT SUPPLY
CURRENT vs. VBUS_ (CHARGER ENABLED)
MAX8895W/X/Y toc02
VBUS_ (V)
INPUT SUPPLY CURRENT (mA)
1412108642
0.5
1.0
1.5
2.0
2.5
0
01
6
BATT UNCONNECTED
SUS_EN = ENU_EN
= CEN = AGND
MAX8895Y VBUS_ INPUT SUPPLY
CURRENT vs. VBUS_ (CHARGER ENABLED)
MAX8895W/X/Y toc05
VBUS_ (V)
INPUT SUPPLY CURRENT (mA)
14128 104 62
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
0
01
6
BATTERY UNCONNECTED
CEN = AGND
MAX8895V/W/X VBUS_ INPUT SUPPLY
CURRENT vs. VBUS_ (CHARGER DISABLED)
MAX8895W/X/Y toc03
VBUS_ (V)
INPUT SUPPLY CURRENT (mA)
1412108642
0.5
1.0
1.5
2.0
2.5
0
01
6
VBAT_ = 4.2V
CEN = INT_3V3
SUS_EN =
ENU_EN = AGND
MAX8895Y VBUS_ INPUT SUPPLY
CURRENT vs. VBUS_ (CHARGER DISABLED)
MAX8895W/X/Y toc06
VBUS_ (V)
INPUT SUPPLY CURRENT (mA)
14128 104 62
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
0
01
6
VBAT_ = 4.2V
CEN = INT_3V3
BATTERY LEAKAGE CURRENT
vs. BATTERY VOLTAGE
MAX8895W/X/Y toc07
VBATT (V)
LEAKAGE CURRENT (µA)
4.03.5
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0
3.0 4.5
BUS_ UNCONNECTED
CEN = AGND
BATTERY LEAKAGE CURRENT
vs. TEMPERATURE
MAX8895W/X/Y toc08
TEMPERATURE (NC)
LEAKAGE CURRENT (µA)
603510-15
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0
-40 85
CHARGE CURRENT vs. BATTERY VOLTAGE
(DEDICATED CHARTER)
MAX8895W/X/Y toc09
BATTERY VOLTAGE (V)
CHARGE CURRENT (mA)
4.03.53.02.5
100
200
300
400
500
600
700
0
2.0 4.5
ENU_EN = SUS_EN = AGND, RISET = 5kI
8 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Typical Operating Characteristics (continued)
(VBAT_ = 4.2V, VBUS_ = 5V, ISET = IDN = CT = SUS_EN = INT_3V3, STDBY = ENU_EN = RWU = CEN = KB_TM = AGND, circuits
of Figures 4 and 5 (MAX8895V/MAX8895X and MAX8895Y, respectively), TA = +25NC, unless otherwise noted.)
CHARGE CURRENT vs. BATTERY VOLTAGE
(LOW-POWER USB)
MAX8895W/X/Y toc10
BATTERY VOLTAGE (V)
CHARGE CURRENT (mA)
4.03.53.02.5
10
20
30
40
50
60
70
80
90
100
0
2.0 4.5
ENU_EN = INT_3V3, SUS_EN = AGND
CHARGE CURRENT vs. BATTERY VOLTAGE
(HIGH-POWER USB)
MAX8895W/X/Y toc11
BATTERY VOLTAGE (V)
CHARGE CURRENT (mA)
4.03.53.02.5
100
200
300
400
500
600
0
2.0 4.5
ENU_EN = SUS_EN = AGND
CHARGER IN DROPOUT
CHARGE CURRENT (DEDICATED CHARGER)
vs. AMBIENT TEMPERATURE
MAX8895W/X/Y toc12
TEMPERATURE (°C)
CHARGE CURRENT (mA)
603510-15
601
602
603
604
605
606
607
608
609
610
600
-40 85
BATTERY REGULATION VOLTAGE
vs. AMBIENT TEMPERATURE
MAX8895W/X/Y toc13
TEMPERATURE (°C)
BATTERY REGULATION VOLTAGE (V)
603510-15
4.185
4.190
4.195
4.200
4.205
4.210
4.215
4.180
-40 85
SYS_ OUTPUT VOLTAGE
vs. VBUS_
MAX8895W/X/Y toc14
VBUS_ (V)
SYS_ OUTPUT VOLTAGE (V)
7654
4.100
4.125
4.150
4.175
4.200
4.225
4.250
4.275
4.300
4.325
4.350
4.375
4.400
4.075
38
ISYS_ = 0mA
ISYS_ = 20mA
VBAT_ = 4.2V
SYS_ OUTPUT VOLTAGE
vs. BATTERY VOLTAGE
MAX8895W/X/Y toc15
VBATT (V)
SYS_ OUTPUT VOLTAGE (V)
4.03.53.02.5
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
0
2.0 4.5
ISYS_ = 100mA
VBUS_ = 5V
ISYS_ = 0A
SYS_ DROPOUT VOLTAGE
vs. LOAD CURRENT
MAX8895W/X/Y toc16
ISYS_ (mA)
SYS_ DROPOUT VOLTAGE (mV)
15001000500
20
40
60
80
100
120
140
0
0 2000
BUS_ UNCONNECTED
DROPOUT MEASURED WHEN
SYS_ DECREASES BY 10%
SYS_ OUTPUT VOLTAGE vs. LOAD CURRENT
(HIGH-POWER USB MODE)
MAX8895W/X/Y toc17
ISYS_ (mA)
SYS_ OUTPUT VOLTAGE (V)
15001000500
3.90
4.00
4.10
4.20
4.30
4.40
3.80
0 2000
SYSTEM LOAD SWITCH
IN DROPOUT
VSYS_ SUPPLEMENTED
BY VBUS_
VBAT_ = 4.2V
SYS_ OUTPUT VOLTAGE vs. LOAD CURRENT
(DEDICATED CHARGER)
MAX8895W/X/Y toc18
ISYS_ (mA)
SYS_ OUTPUT VOLTAGE (V)
15001000500
3.95
4.00
4.05
4.10
4.15
4.20
4.25
4.30
4.35
4.40
3.90
0 2000
SYSTEM LOAD SWITCH IN DROPOUT
VSYS_ SUPPLEMENTED
BY VBUS_
VBAT_ = 4.2V, NOKIA AC-10U
9Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Typical Operating Characteristics (continued)
(VBAT_ = 4.2V, VBUS_ = 5V, ISET = IDN = CT = SUS_EN = INT_3V3, STDBY = ENU_EN = RWU = CEN = KB_TM = AGND, circuits
of Figures 4 and 5 (MAX8895V/MAX8895X and MAX8895Y, respectively), TA = +25NC, unless otherwise noted.)
INT_3V3 VOLTAGE vs. BUS_ VOLTAGE
MAX8895W/X/Y toc19
VBUS_ (V)
VINT_3V3 (V)
7.06.05.04.0
3.05
3.10
3.15
3.20
3.25
3.30
3.35
3.00
3.0 8.0
100mA CHARGE
CURRENT
VBAT_ = 4V
50mA CHARGE
CURRENT
CHARGE PROFILE
(USB 2.0 CHARGER)
MAX8895W/X/Y toc21
TIME (min)
VBATT (V)
275250200 22550 75 100 125 150 17525
3.40
3.50
3.60
3.70
3.80
3.90
4.00
4.10
4.20
4.30
3.30
50
100
150
200
250
300
350
400
450
500
0
0 300
VBAT_
IBAT_
MOTOROLA BC60 860mAh
CCT = 0.2µF
RISET = 3.74k
I
RIDN = 243k
I
IBATT (mA)
TIME (x 10-8) (s)
D+, D- SIGNALS (V)
8.07.05.0 6.02.0 3.0 4.01.0
-0.5
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
MAX8895Y EYE DIAGRAM
MAX8895W/X/Y toc23
CHARGE PROFILE
(NOKIA AC-10 CHARGER)
MAX8895W/X/Y toc20
TIME (min)
VBATT (V)
IBATT (mA)
27525025 50 75 125 150 175 200100 225
3.60
3.70
3.80
3.90
4.00
4.10
4.20
4.30
3.50
0 300
1000
900
800
700
600
500
400
300
200
100
0
MOTOROLA BC60 860mAh
CCT = 0.2µF
RISET = 1.87k
I
RIDN = 243k
I
VBAT_
IBAT_
TIME (x 10-7) (s)
D+, D- SIGNALS (V)
6.05.01.0 2.0 3.0 4.0
0.1
0.6
1.1
1.6
2.1
2.6
3.1
3.6
0
MAX8895V/W/X EYE DIAGRAM
MAX8895W/X/Y toc22
MAX8895W/X/Y toc24
0V
0V
5V/div
5V/div
5V/div
5V/div
0V
0V
VD-
VD+
VSYS
VBUS
200ms/div
DEDICATED CHARGER CONNECT
10 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Typical Operating Characteristics (continued)
(VBAT_ = 4.2V, VBUS_ = 5V, ISET = IDN = CT = SUS_EN = INT_3V3, STDBY = ENU_EN = RWU = CEN = KB_TM = AGND, circuits
of Figures 4 and 5 (MAX8895V/MAX8895X and MAX8895Y, respectively), TA = +25NC, unless otherwise noted.)
MAX8895W/X/Y toc25
0V
0V
0V
5V/div
5V/div
5V/div
5V/div
0V
VBAT_
VSYS_
VINT_3V3
VBUS_
200ms/div
RSYS_ = 100I
DEDICATED CHARGER DISCONNECT
MAX8895W/X/Y toc27
0V
0V
5V/div
5V/div
5V/div
500mA/div
0V
0A
VD-
VD+
IBUS
VBUS
400ms/div
MAX8895Y USB HIGH-POWER
2.0 CONNECT
MAX8895W/X/Y toc29
0mA
0V
0V
5V/div
2V/div
2V/div
200mA/div
0V
VD-
VD+
VBUS_
IBUS_
2ms/div
RSYS_ = 100I
MAX8895Y USB HIGH-POWER
2.0 DISCONNECT
MAX8895W/X/Y toc26
0V
0V
5V/div
5V/div
5V/div
500mA/div
0V
0A
VD-
VD+
IBUS
VBUS
400ms/div
MAX8895V/W/X HIGH-POWER 2.0
MAX8895W/X/Y toc28
0mA
0V
0V
5V/div
2V/div
2V/div
100mA/div
0V
VD-
VD+
VBUS_
IBUS_
20ms/div
RSYS_ = 100I
MAX8895V/W/X USB HIGH-POWER
2.0 DISCONNECT
MAX8895W/X/Y toc30
0V
0V
0mA
2V/div
1V/div
200mA/div
2V/div
0V
IBUS_
VD+
VD-
1ms/div
VFLT
MAX8895V/W/X USB AUTOSUSPEND
11Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Typical Operating Characteristics (continued)
(VBAT_ = 4.2V, VBUS_ = 5V, ISET = IDN = CT = SUS_EN = INT_3V3, STDBY = ENU_EN = RWU = CEN = KB_TM = AGND, circuits
of Figures 4 and 5 (MAX8895V/MAX8895X and MAX8895Y, respectively), TA = +25NC, unless otherwise noted.)
MAX8895W/X/Y toc31
0V
0V
0mA
2V/div
1V/div
200mA/div
2V/div
0V
IBUS_
VD+
VD-
1ms/div
VFLT
MAX8895Y USB AUTOSUSPEND
MAX8895W/X/Y toc33
0V
0mA
2V/div
200mA/div
2V/div
2V/div
0V
0V
IBUS_
VD+
VD-
1s/div
VFLT
MAX8895Y USB RESUME
MAX8895W/X/Y toc32
0V
0V
0mA
2V/div
1V/div
200mA/div
2V/div
0V
IBUS_
VD+
VD-
1s/div
VFLT
MAX8895V/W/X USB RESUME
PREQUALIFICATION TIMEOUT
vs. CT CAPACITANCE
MAX8895W/X/Y toc34
C
CT
(pF)
PREQUALIFICATION TIMEOUT (s)
80,00060,00020,000 40,000
200
400
600
800
1200
1000
1400
1600
0
0 100,000
FAST-CHARGE TIMEOUT
vs. CT CAPACITANCE
MAX8895W/X/Y toc35
CCT (pF)
FAST-CHARGE TIMEOUT (s)
80,00060,00040,00020,000
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
10,000
0
0 100,000
12 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Pin Configurations
TOP VIEW
(BUMP SIDE DOWN)
A
B
C
D
WLP
E
1234
ISET STDBY BAT_A SYS_A BUS_A
IDN CHG BAT_B SYS_B BUS_B
ENU_EN PREQ UOK KB_TM AGND
SUS_EN RWU CEN FLT D+
CT THM INT_3V3 DGND D-
5
+
MAX8895V
MAX8895X
TOP VIEW
(BUMP SIDE DOWN)
A
B
C
D
WLP
E
1234
ISET STDBY BAT_A SYS_A BUS_A
IDN CHG BAT_B SYS_B BUS_B
XIN PREQ UOK KB_TM AGND
XOUT RWU CEN FLT D+
CT THM INT_3V3 DGND D-
5
+
MAX8895Y
TOP VIEW
(BUMP SIDE DOWN)
A
B
C
D
WLP
E
1234
ISET STDBY BAT_A SYS_A BUS_A
IDN CHG_
TYPE BAT_B SYS_B BUS_B
ENU_EN DET_DONE UOK KB_TM AGND
SUS_EN IBUS_DEF CEN FLT D+
CT THM INT_3V3 DGND D-
5
+
MAX8895W
13Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Pin Description
PIN
NAME
FUNCTION
MAX8895W MAX8895V/
MAX8895X MAX8895Y
A1 ISET ISET ISET
Maximum Fast-Charge Current Selection. Connect a resistor from ISET to
AGND to set the fast-charge current from 0.1A to 1.85A.
IFCHG = 3000/RISET
If ISET is connected to INT_3V3 the default IFCHG is set as maximum charge
current.
ISET can also be used to monitor the actual current charging the battery.
See the Monitoring Charge Current section for details.
A2 STDBY STDBY STDBY
Standby Mode Enable. Connect STDBY to AGND to enter automatic detect
mode. In automatic detect mode, the MAX8895V/MAX8895W/MAX8895X
determine when to enter suspend mode depending on the status of the
SUS_EN logic input. When using the MAX8895Y, the IC always starts in
automatic suspend mode. Connect STDBY to INT_3V3 or drive logic-high to
force the MAX8895_ into suspend mode regardless of external conditions.
A3 BAT_A BAT_A BAT_A
Li+ Battery Connection (VBAT_). Connect a single-cell Li+ battery from VBAT_
to DGND. The battery charges from VSYS_ when a valid source is present
at VBUS_. VBAT_ powers VSYS_ when VBUS_ power is not present, or when
the VSYS_ load exceeds the input current limit. Bypass VBAT_ to DGND with
a 10FF X5R or X7R ceramic capacitor. Both BAT_A and BAT_B must be
connected together externally.
B3 BAT_B BAT_B BAT_B
A4 SYS_A SYS_A SYS_A
System Supply Output (VSYS_). VSYS_ is connected to VBAT_ through an
internal 55mI system load switch when VBUS_ is invalid, or when the VSYS_
load is greater than the input current limit. When a valid voltage is present
at VBUS_, VSYS_ is limited to 4.35V when using the MAX8895V/MAX8895X/
MAX8895Y, and 4.53V when using the MAX8895W. When the system load
current (ISYS_) exceeds the VBUS_ current limit VBAT_ also powers VSYS_ to
maintain the load current. Bypass VSYS_ to DGND with a 10FF X5R or X7R
ceramic capacitor. Both SYS_A and SYS_B must be connected together
externally.
B4 SYS_B SYS_B SYS_B
A5 BUS_A BUS_A BUS_A USB Power Input (VBUS_). During initial connection of an external device,
the MAX8895_ identifies the type of connection established and set the input
current limit accordingly. Bypass VBUS_ to DGND with a 10FF X5R or X7R
ceramic capacitor. Both BUS_A and BUS_B must be connected together
externally.
B5 BUS_B BUS_B BUS_B
B1 IDN IDN IDN
Charge Termination Current Threshold. Connect a resistor from IDN to AGND
to set the termination current threshold from 10mA to 160mA.
ITERM = 2400/RIDN
If IDN is connected to INT_3V3, the termination current is set to the default
ICHG_DONE threshold.
14 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Pin Description (continued)
PIN
NAME
FUNCTION
MAX8895W MAX8895V/
MAX8895X MAX8895Y
B2
— CHG CHG
Active-Low, Charging Indicator. CHG is an open-drain output that is pulled
low when the battery is in prequalification mode, fast-charge mode, or top-off
states. Otherwise, CHG is high impedance.
CHG_TYPE — —
CHG_TYPE is used to indicate capacity of input current. IF CHG_TYPE is
high, the input current can be greater than or equal to 500mA. If CHG_TYPE
is low, the input current is 100mA from the USB 2.0 host.
C1
— — XIN
Crystal Oscillator Input. Connect XIN to one side of a parallel resonant
12MHz ±0.25% crystal and a capacitor to AGND. XIN can also be driven by
an external clock referenced to INT_3V3.
— ENU_EN —
Automatic Enumeration Enable. Connect ENU_EN to AGND to allow the
MAX8895V/MAX8895X to automatically perform enumeration. Connect to
INT_3V3 or drive logic-high to force the input current limit to 100mA without
performing an adapter type detection.
ENU_EN — —
Automatic Enumeration Enable. Connect ENU_EN to AGND to allow the
MAX8895W to automatically perform enumeration. By connecting ENU_EN
to INT_3V3 or drive logic-high, disables automatic enumeration and sets the
input current limit to level determined by the IBUS_DEF if a USB 2.0 device is
detected.
C2
—PREQ PREQ Active-Low, Prequalification Charging Output. PREQ is an open-drain output
that is pulled low when the charger enters the prequalification state.
DET_DONE — —
Active-Low Adapter-Type Detection Done Output. DET_DONE is an open-
drain output that is pulled low when adapter detection is completed. DET_
DONE is high impedance in suspend mode.
C3 UOK UOK UOK Active-Low, VBUS_ Power-OK Output. UOK is an open-drain output that is
pulled low when a valid input is detected at VBUS_.
C4 KB_TM KB_TM KB_TM Keyboard Test Mode. In normal operation, connect KB_TM to AGND. This
input is only used during USB certification.
C5 AGND AGND AGND Analog Ground. Both AGND and DGND should be connected together at the
negative terminal of the battery.
D1
— — XOUT
Crystal Oscillator Output. Connect XOUT to one side of a parallel resonant
12MHz Q0.25% crystal and a capacitor to AGND. Leave XOUT unconnected
if XIN is driven by an external clock.
SUS_EN SUS_EN —
Automatic Suspend Mode Detection Enable. Connect SUS_EN to AGND
to disable the automatic suspend mode detection. Connect SUS_EN to
INT_3V3 or drive logic-high to enable the automatic detection of suspend
mode.
D2
— RWU RWU
Remote Wake-up. Connect RWU to AGND or logic-low for remote wake-
ups whenever the device is put into suspend mode and the supervisor
determines that more current is needed.
IBUS_DEF — —
Sets USB Input Current if Adapter is Detected as a USB 2.0 Device and
ENU_EN is Logic-High. If IBUS_DEF is connected high, the input current limit
is set to 500mA. If IBUS_DEF is connected low or to ground, the input current
limit is set to 100mA.
15Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Pin Description (continued)
PIN
NAME
FUNCTION
MAX8895W MAX8895V/
MAX8895X MAX8895Y
D3 CEN CEN CEN
Charger Enable Input. Connect CEN to AGND to enable battery charging
when a valid source is connected at VBUS_. Connect CEN to INT_3V3 or
drive logic-high to disable battery charging. In this condition the USB state
machine is still active, and VSYS_ is powered from VBUS_ under normal
conditions and supplemented from VBAT_ if sufficient current is not available
from VBUS_ input.
D4 FLT FLT FLT
Active-Low Fault Output. FLT is an open-drain output that is pulled low when
the battery charger timer expires before prequalification or fast-charge
completes. FLT is also pulled low during adapter type detection or if USB
enumeration fails.
D5 D+ D+ D+
USB D+ signal. Connect D+ to a USB “B” connector through a 33I series
resistor. The 1.5kI D+ pullup resistor is internal to the device (for MAX8895Y
only).
E1 CT CT CT
Timer Set Capacitor. Connect a capacitor from CT to AGND to set the fault
timers for prequalification and fast-charge.
tPREQUAL = 16min x (CCT/0.068FF)
tFCHG = 100min x (CCT/0.068FF)
tMTCHG = 4min x (CCT/0.068FF)
If CT is connected directly to AGND, the default timers are used.
E2 THM THM THM
Thermistor Input. Connect a negative temperature coefficient (NTC)
thermistor that has good thermal contact with the battery from THM to AGND.
Connect a resistor equal to the thermistor at TA = +25NC resistance from
THM to INT_3V3. Charging is suspended when the thermistor is outside
the hot and cold limits. Connect THM to AGND to disable the thermistor
temperature sensor.
E3 INT_3V3 INT_3V3 INT_3V3
LDO Output. INT_3V3 is the output of an LDO that powers the internal
circuitry. INT_3V3 is powered from the VBUS_ input. Connect a 0.1FF
capacitor from INT_3V3 to AGND.
E4 DGND DGND DGND Digital Ground. Both AGND and DGND should be connected together at the
negative terminal of the battery.
E5 D- D- D-
USB D- Signal. Connect D- to a USB “B” connector through a 33I series
resistor. The 1.5kI D- pullup resistor is internal to the device (for MAX8895V/
MAX8895W/MAX8895X only).
16 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Figure 1. MAX8895V/MAX8895X Block Diagram
Li+ BATTERY
CHARGER AND
SYS LOAD SWITCH
CHARGER
CURRENT
VOLTAGE
CONTROL
VBUS_
OUT OF
RANGE
VBUS_ VALID
USB POWER
MANAGEMENT
D+
BUS_A
BUS_B
SYS_A
SYS_B
SET INPUT
CURRENT LIMIT
SET INPUT
CURRENT LIMIT
IC THERMAL
REGULATION
ILIM ILIM-
ISYS
ISYS_
USB INTERFACE
LOGIC
POR
ILIM
RTB
RT
RISET
RIDN
CCT
CINT_3V3
3.3V FOR INTERNAL
USB TRANSCEIVER
TO
SYSTEM LOAD
ICHG_MAX
ICHG
USB ADAPTER
TYPE DETECTION
AND
ENUMERATION
UOK
RD+
D-
D+
GND
D-
VBUS
BAT-
NTC
BAT+
RD-
SUPPORT REMOTE
WAKE-UP
FORCE REMOTE
WAKE-UP
CHARGING
TERMINATED
CHARGING
IN PROGRESS
PRECHARGING
TERMINATED
PRECHARGING
IN PROGRESS
RWU
AUTOMATED SUSPEND
ENABLED
AUTOMATED SUSPEND
DISABLED
SUS_EN
BAT_A
BAT_B
ISET
THM
INT_3V3
CHG
AUTOMATIC ENUMERATION
DISABLED
AUTOMATIC ENUMERATION
ENABLED
ENU_EN
KEYBOARD TEST MODE
ENABLED
KEYBOARD TEST MODE
DISABLED
KB_TM
FORCED STANDBY
MODE
AUTOMATIC STANDBY
MODE
STDBY
INT_3V3
NO FAULT
FAULT
CHARGER DISABLED
CHARGER ENABLED
DGND AGND
THERMISTOR
MONITOR
CHARGE
TERMINATION
AND
MONITOR
CHARGE
TIMER
MAX8895V
MAX8895X
FLT
CEN
CT
PREQ
IDN
17Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Figure 2. Differential Input Configuration
Li+ BATTERY
CHARGER AND
SYS LOAD SWITCH
CHARGER
CURRENT
VOLTAGE
CONTROL
VBUS_
OUT OF
RANGE
VBUS_ VALID
USB POWER
MANAGEMENT
D+
BUS_A
BUS_B
SYS_A
SYS_B
INPUT
CURRENT LIMIT
SET INPUT
CURRENT LIMIT
IC THERMAL
REGULATION
ILIM ILIM-
ISYS
ISYS_
USB INTERFACE
LOGIC
POR
ILIM
RTB
RISET
RIDN
CCT
CINT_3V3
3.3V FOR INTERNAL
USB TRANSCEIVER
TO
SYSTEM LOAD
ICHG_MAX
ICHG
USB ADAPTER
TYPE DETECTION
AND
ENUMERATION
UOK
RD+
D-
D+
GND
D-
VBUS
BAT-
NTC
BAT+
RD-
SUPPORT REMOTE
WAKE-UP
FORCE REMOTE
WAKE-UP
CHARGING
TERMINATED
CHARGING
IN PROGRESS
PRECHARGING
TERMINATED
PRECHARGING
IN PROGRESS
RWU
KEYBOARD TEST MODE
ENABLED
KEYBOARD TEST MODE
DISABLED
KB_TM
BAT_A
BAT_B
ISET
THM
INT_3V3
CHG
FORCED STANDBY
MODE
AUTOMATIC STANDBY
MODE
STDBY
INT_3V3
NO FAULT
FAULT
CHARGER DISABLED
CHARGER ENABLED
DGND AGND
THERMISTOR
MONITOR
CHARGE
TERMINATION
AND
MONITOR
CHARGE
TIMER
MAX8895Y
FLT
CEN
CT
PREQ
IDN
XIN
XOUT
OSCILLATOR
RT
18 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Figure 3. MAX8895W Block Diagram
Li+ BATTERY
CHARGER AND
SYS LOAD SWITCH
CHARGER
CURRENT
VOLTAGE
CONTROL
VBUS_
OUT OF
RANGE
VBUS_ VALID
USB POWER
MANAGEMENT
D+
BUS_A
BUS_B
SYS_A
SYS_B
INPUT
CURRENT LIMIT
SET INPUT
CURRENT LIMIT
IC
THERMAL
REGULATION
ILIM ILIM-
ISYS
ISYS_
USB INTERFACE
LOGIC
POR
ILIM
RTHM
RISET
RIDN
CINT_3V3
3.3V FOR USB
TRANSCEIVER
TO
SYSTEM
LOAD
ICHG_MAX
ICHG
USB ADAPTER
TYPE DETECTION
AND
ENUMERATION
UOK
D-
D+
GND
D-
VBUS
BAT-
NTC
BAT+
BAT_A
BAT_B
ISET
THM
INT_3V3
KEYBOARD TEST MODE ENABLED
KEYBOARD TEST MODE DISABLED
KB_TM
FORCED STANDBY MODE
AUTOMATIC STANDBY MODE
STDBY
INT_3V3
NO FAULT
FAULT
CHARGER DISABLED
CHARGER ENABLED
THERMISTOR
MONITOR
CHARGE
TERMINATION
AND
MONITOR
CHARGE
TIMER
MAX8895W
FLT
CEN
IDN
DGND AGND
SUS_EN
AUTOMATIC SUSPEND ENABLED
AUTOMATIC SUSPEND DISABLED
ENU_EN
AUTOMATIC SUSPEND ENABLED
AUTOMATIC SUSPEND DISABLED
ADAPTER DETECTION IN PROGRESS
ADAPTER DETECTION COMPLETE
DET_DONE
CHG_TYPE
R500mA INPUT CURRENT LIMIT
100mA MAX. INPUT CURRENT LIMIT
IBUS_DEF
INPUT CURRENT LIMIT SET TO 500mA
INPUT CURRENT LIMIT SET TO 100mA
CTIMER
CT
19Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Figure 4. MAX8895V/MAX8895X Typical Application Circuit
BUS_A
MICRO
USB-B
BUS_B
SYS_A
SYS_B
RD+
D+
D-
GND
VBUS
CBUS CSYS
RD-
RWU
SUS_EN
ENU_EN
KB_TM
STDBY
PREQ
UOK
D+
D-
BAT_A
BAT_B
THM
INT_3V3
ISET
CBAT 1-CELL Li+
RTB
CINT_3V3
RISET
RTP RTS
CCT
IDN
CT
RIDN
CEN
CHG
FLT
DGND AGND
MAX8895V
MAX8895X
RT
NAME VALUE FUNCTION
CBUS 10FF, 16V Decoupling of input supply.
CSYS 10FF, 6.3V Decoupling of system rail.
CBAT 10FF, 6.3V Decoupling of battery rail.
RTUser dependent Thermistor for thermal sensing. See the Thermistor Input (THM) section for details.
RTB, RTP, RTS User dependent Bias resistors for thermal sensing. See the Thermistor Input (THM) section for details.
CINT_3V3 0.1FF, 6.3V Decoupling of internal 3.3V rail.
CCT 1000pF to 0.2FFCapacitor to set charge timer, optional. See the Fault Output (FLT) and Charge Timer (CT) section
for details.
RISET 1.875kI to 30kIResistor to set maximum charging current, optional.
RIDN 15kI to 240kIResistor to set termination current for charger, optional.
RD+, RD- 33ID+/D- serial impedance.
20 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Figure 5. MAX8895Y Typical Application Circuit
BUS_A
MICRO
USB-B
BUS_B
SYS_A
SYS_B
RD+
D+
D-
GND
VBUS
CBUS
CXTAL_IN
CXTAL_OUT
XTAL
CSYS
RD-
RWU
KB_TM
STDBY
D+
D-
THM
INT_3V3
ISET
RTB
CINT_3V3
RISET
RTP RTS
CCT
IDN
CT
RIDN
PREQ
UOK
CHG
FLT
CEN
XIN
XOUT
MAX8895Y
DGND AGND
BAT_A
BAT_B
CBAT 1-CELL Li+
RT
NAME VALUE FUNCTION
CBUS 10FF, 16V Decoupling of input supply.
CSYS 10FF, 6.3V Decoupling of system rail.
CBAT 10FF, 6.3V Decoupling of battery rail.
RTUser dependent Thermistor for thermal sensing. See the Thermistor Input (THM) section for details.
RTB, RTP, RTS User dependent Bias resistors for thermal sensing. See the Thermistor Input (THM) section for details.
CINT_3V3 0.1FF, 6.3V Decoupling of internal 3.3V rail.
XTAL 12MHz 2500ppm MAX8895Y only, clock source for full-speed mode, requires a 2500ppm or better accuracy.
CXTAL_IN User dependent MAX8895Y only, crystal load capacitor, only required for full-speed operation. See the External
Crystal/Ceramic Resonator section for details.
CXTAL_OUT User dependent MAX8895Y only, crystal load capacitor, only required for full-speed operation.
CCT 1000pF to 0.2FFCapacitor to set charge timer, optional. See the Fault Output (FLT) and Charge Timer (CT) section
for details.
RISET 1.875kI to 30kIResistor to set maximum charging current, optional.
RIDN 15kI to 240kIResistor to set termination current for charger, optional.
RD+, RD- 33ID+/D- serial impedance.
21Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Figure 6. MAX8895W Typical Application Circuit
BUS_A
MICRO
USB-B
BUS_B
SYS_A
SYS_B
RD+
D+
D-
GND
VBUS
CBUS CSYS
RD-
DET_DONE
SUS_EN
ENU_EN
D+
D-
THM
INT_3V3
ISET
RTB
CINT_3V3
RISET
RTP RTS
CCT
IDN
CT
RIDN
UOK
FLT
KB_TM
STDBY
CEN
CHG_TYPE
IBUS_DEF
MAX8895W
DGND AGND
BAT_A
BAT_B
CBAT 1-CELL Li+
RTHM
NAME VALUE FUNCTION
CBUS 10FF, 16V Decoupling of input supply.
CSYS 10FF, 6.3V Decoupling of system rail.
CBAT 10FF, 6.3V Decoupling of battery rail.
RTHM User dependent Thermistor for thermal sensing. See the Thermistor Input (THM) section for details.
RTB, RTP, RTS User dependent Bias resistors for thermal sensing. See the Thermistor Input (THM) section for details.
CINT_3V3 0.1FF, 6.3V Decoupling of internal 3.3V rail.
CCT 1000pF to 0.2FFCapacitor to set charge timer, optional. See the Fault Output (FLT) and Charge Timer (CT) section
for details.
RISET 1.875kI to 30kIResistor to set maximum charging current, optional.
RIDN 15kI to 240kIResistor to set termination current for charger, optional.
RD+, RD- 33ID+/D- serial impedance.
22 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Detailed Description
The MAX8895_ is an integrated 1-cell Li+ charger with
USB enumeration capability. All power switches for
charging and switching the load between battery and
external power are internal. No external MOSFETS are
required.
The MAX8895_ makes it possible to negotiate more
than 100mA of charging current from a USB host or hub
without processor intervention. The MAX8895_ also auto-
matically detects a dedicated charger or USB charger
and set the input current limit accordingly. The battery
charge current can be set up to 1.85A. Input power not
used by the system charges the battery.
USB Interface
An integrated USB peripheral controller provides auto-
enumeration for full-speed (MAX8895Y) and low-speed
(MAX8895V/MAX8895W/MAX8895X) modes.
The USB controller executes the adapter detection
sequence, which consists of detecting the type of
adapter that is externally connected and setting the input
current limit accordingly.
If attached to a USB charger (host or hub) or a USB 2.0
(host or hub), it enumerates as an HID device and nego-
tiates the maximum charging current level (from VBUS_).
The MAX8895V/MAX8895W/MAX8895X operate in low-
speed mode, using an internal 6MHz oscillator, and does
not require an external crystal to be USB compliant. The
MAX8895Y operates in full-speed mode and requires an
external 12MHz crystal.
According to the USB 2.0 specification, a low-speed
device is not allowed to use a standard USB “B” con-
nector. This is why MAX8895_ is available in both a
low- and full-speed version. This makes it possible to
use a custom or captive cable for low-speed mode
using the MAX8895V/MAX8895W/MAX8895X and still be
USB compliant. Operating in full-speed mode, using the
MAX8895Y allows use of a standard USB “B” connector.
D+ and D-
The internal USB full speed (MAX8895Y)/low-speed
(MAX8895V/MAX8895W/MAX8895X) transceiver is
brought out to the bidirectional data pins D+ and D-.
These pins are ESD protected up to Q8kV (HBM).
Connect these pins to a USB “B” custom connector
through external 33I series resistors. The MAX8895V/
MAX8895X provide an automatic switchable 1.5kI pul-
lup resistor for D-, while the MAX8895Y provides an auto-
matic switchable 1.5kI pullup resistor for D+.
Adapter Detection
When an adapter is present on VBUS_, the MAX8895_
examines the external device to identify the type of
adapter connected.
The possible adapter types are:
U Dedicated charger
U USB charger (host or hub)
U USB 2.0 (host or hub) low power
U USB 2.0 (host or hub) high power
Each of these different devices has different current
capability as shown in Table 1.
Figure 7. USB Rise and Fall Timing
Figure 8. Load for D+/D- AC Measurements
Table 1. Adapter Types
USB Timing
tRISE tFALL
90%
10%
MAX8895V
MAX8895W
MAX8895X
MAX8895Y
D+ OR D-
CL = 50pF 15kI
TEST POINT
3.3Ω
ADAPTER TYPE OUTPUT VOLTAGE OUTPUT CURRENT
Dedicated charger 4.75V to 5.25V at ILOAD < 500mA
2.0V to 5.25V for ILOAD R500mA 500mA to 1.85A
USB charger 4.75V to 5.25V at ILOAD < 500mA
0 to 5.25V for ILOAD R 500mA
500mA to 900mA for low speed, full speed
500mA to 1.5A for low speed and full speed
USB 2.0 low power 4.25V to 5.25V 100mA (max)
USB 2.0 high power 4.75V to 5.25V 500mA (max)
23Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
When an adapter is connected to the MAX8895_, a
series of tests is performed to identify the type of device
connected. The sequence is done according to the flow
charts in Figures 7 and 8. Figures 9, 10, and 11 show the
adapter-type detection timing.
Figure 9. MAX8895X Flow Chart for Adapter Type Detection Figure 10. MAX8895V Flow Chart for Adapter Type Detection
DISABLE VDP_SRC
DISABLE VDM_SINK
DISABLE DM_PU
DISABLE I_DM_PD
DISABLE DP_CD_PU
DISABLE VDP_SRC
DISABLE VDM_SINK
ENABLE I_DM_PD
ENABLE DP_CD_PU
DELAY tDP_SRC_HC
DISABLE VDP_SRC
DISABLE VDM_SINK
ILIM = IENU
DELAY tDP_SRC_HC
ENABLE DM_PU
ENABLE VDP_SRC
ENABLE VDM_SINK
DELAY tDP_SRC_ON
DEBOUNCE
tUSB_DB
USB_OK = HIGH NO
NO
NO
YES
YES
YES
DISABLE VDP_SRC
DISABLE VDM_SINK
DISABLE DM_PU
DISABLE I_DM_PD
DISABLE DP_CD_PU
ILIM = ISUS
STDBY = HIGH
YES ILIM = IUSB_LP
ILIM = IDCHG
ILIM = IUSB_CHG
ENU_EN = HIGH
YES
VDAT_REF
P
VDM
< VDM_IH
NO
DISABLE I_DP_PD
DISABLE
DP_CD_PU
ENABLE DM_PU
ILIM = IUSS_CHG
YES
DM > VDM_IH
NO
NO NO
YES
YES
YES
YES
YES
YES
DISABLE DM_PU
ILIM = ISUS
DELAY tFAULT
ENUMERATION
SUCCEEDED
NO
USB
SUSPEND?
NO
SUS_EN = LOW
NO
NO
NO
NO
USB HOST
D- HIGH TO LOW
TRANSITION
USB_OK = LOW
FROM ANY CONDITION
STDBY = HIGH
FROM ANY
CONDITION,
USB_OK = _HIGH
YES
ENUMERATION
SUCCEEDED
DISABLE DP_PU
ILIM = ISUS
DELAY tFAULT
ILIM = USB_LP
OR USB_HP
ILIM = ISUS
DELAY tRWU
INITIATE
RESUME
DELAY tRE_ENUM
YES
CHARGE
DONE
RWU
SUPPORTED
BY HOST
RWU = LOW
DISABLE VDP_SRC
DISABLE VDM_SINK
DISABLE DM_PU
DISABLE I_DM_PD
DISABLE DP_CD_PU
DISABLE VDP_SRC
DISABLE VDM_SINK
ENABLE I_DM_PD
ENABLE DP_CD_PU
DELAY tDP_SRC_HC
DISABLE VDP_SRC
DISABLE VDM_SINK
ILIM = IENU
DELAY tDP_SRC_HC
ENABLE DM_PU
ENABLE VDP_SRC
ENABLE VDM_SINK
DELAY tDP_SRC_ON
DEBOUNCE
tUSB_DB
USB_OK = HIGH NO
NO
NO
YES
YES
YES
DISABLE VDP_SRC
DISABLE VDM_SINK
DISABLE DM_PU
DISABLE I_DM_PD
DISABLE DP_CD_PU
ILIM = ISUS
STDBY = HIGH
YES ILIM = IUSB_LP
ILIM = IDCHG
ILIM = IUSB_CHG
ENU_EN = HIGH
YES
VDAT_REF
P
VDM
< VDM_IH
NO
DISABLE I_DP_PD
DISABLE
DP_CD_PU
ENABLE DM_PU
ILIM = IUSS_CHG
YES
DM > VDM_IH
NO
NO NO
YES
YES
YES
YES
YES
NO
DISABLE DM_PU
ILIM = ISUS
DELAY tFAULT
ENUMERATION
SUCCEEDED
NO
USB
SUSPEND?
NO
SUS_EN = LOW
NO
NO
YES
NO
USB HOST
D- HIGH TO LOW
TRANSITION
USB_OK = LOW
FROM ANY CONDITION
STDBY = HIGH
FROM ANY
CONDITION,
USB_OK = _HIGH
YES
ENUMERATION
SUCCEEDED
DISABLE DP_PU
ILIM = ISUS
DELAY tFAULT
ILIM = USB_LP
OR USB_HP
ILIM = ISUS
DELAY tRWU
INITIATE
RESUME
DELAY tRE_ENUM
YES
CHARGE
DONE
RWU = LOW
RWU
SUPPORTED
BY HOST
24 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Figure 11. MAX8895Y Flow Chart for Adapter Type Detection
DISABLE VDP_SRC
DISABLE VDM_SINK
DISABLE DP_PU
DISABLE I_DM_PD
DISABLE DP_CD_PU
DISABLE VDP_SRC
DISABLE VDM_SINK
ENABLE I_DM_PD
ENABLE DP_CDC_PU
DELAY tDP_SRC_HC
DISABLE VDP_SRC
DISABLE VDM_SINK
ILIM = IENU
DELAY tDP_SRC_HC
ENABLE DP_PU
ENABLE VDP_SRC
ENABLE VDM_SINK
DELAY tDP_SRC_ON
DEBOUNCE
tUSB_DB
USB_OK = HIGH NO
NO
NO
YES
YES
YES
DISABLE VDP_SRC
DISABLE VDM_SINK
DISABLE DP_PU
DISABLE I_DM_PD
DISABLE DP_CD_PU
ILIM = ISUS
STDBY = HIGH
YES ILIM = IUSB_LP
ILIM = IDCHQ
ILIM = IUSB_CHG
ENU_EN = HIGH
YES NO
DISABLE I_DP_PD
DISABLE
DP_CD_PU
ENABLE DP_PU
ILIM = IUSS_CHG
YES
DM > VDM_IH
NO
NO
YES
YES
YES
YES
YES
YES
DISABLE DP_PU
ILIM = ISUS
DELAY tFAULT
ENUMERATION
SUCCEEDED
NO
USB
SUSPEND?
NO
NO
SUS_EN = LOW
NO
NO
NO
NO
USB HOST
D+ HIGH TO LOW
TRANSITION
USB_OK = LOW
FROM ANY CONDITION
STDBY = HIGH
FROM ANY
CONDITION,
USB_OK = _HIGH
YES
ENUMERATION
SUCCEEDED
DISABLE DP_PU
ILIM = ISUS
DELAY tFAULT
ILIM = USB_LP
OR USB_HP
ILIM = ISUS
DELAY tRWU
INITIATE
RESUME
DELAY tRE_ENUM
YES
CHARGE
DONE
RWU
SUPPORTED
BY HOST
RWU = LOW
VDAT_REF
P
VDM
< VDM_IH
25Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Figure 12. MAX8895W Flow Chart for Adapter Type Detection
DEBOUNCE
tUSB_DB
USB_OK = HIGH
NO
NO
YES
YES
YES
DISABLE VDP_SRC
DISABLE VDM_SINK
DISABLE DM_PU
DISABLE I_DM_PD
DISABLE DP_CD_PU
ILIM = USB_LP
or USB_HP
STDBY = HIGH
ENABLE VDP_SRC
ENABLE VDM_SINK
DELAY tDP_SRC_ON
ILIM = IDCHG
DET_DONE = 0
IBUS_DEF = 1
ILIM = IUSB_CHG
DISABLE VDP_SRC
DISABLE VDM_SINK
ILIM = IENU
DELAY tDP_SRC_HC
ENABLE DP_PU
DISABLE VDP_SRC
DISABLE VDM_SINK
ENABLE I_DM_PD
ENABLE DP_CDC_PU
DELAY tDP_SRC_HC
YES NO
YES
DM > VDM_IH
NO
NO
YES
YES
YES
YES
YES
YES
DISABLE DM_PU
ILIM = ISUS
DELAY tFAULT
ENUMERATION
SUCCEEDED
NO
USB
SUSPEND?
NO
NO
SUS_EN = LOW
NO
NO
NO
USB HOST
D+ HIGH TO LOW
TRANSITION
USB_OK = LOW
FROM ANY CONDITION
STDBY = HIGH
FROM ANY
CONDITION,
USB_OK = _HIGH
YES
ENUMERATION
SUCCEEDED
DISABLE DM_PU
ILIM = ISUS
DELAY tFAULT
ILIM = VIBUS_DEF
DELAY tRWU
INITIATE
RESUME
YES
CHARGE
DONE
RWU
SUPPORTED
BY HOST?
DM = VDAT_REF
DISABLE I_DP_PD
DISABLE DP_CD_PU
ENABLE DM_PU
ILIM = IUSB_CHG
DET_DONE = 0
IBUS_DEF = 1
ENU_EN =
LOW
DET_DONE = 0
ILIM = ISUS
DET_DONE = 0
DISABLE VDP_SRC
DISABLE VDM_SINK
DISABLE DP_PU
DISABLE I_DM_PD
DISABLE DP_CD_PU
ILIM = ISUS
DET DONE = 1
26 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Once the type of adapter is determined, the MAX8895_
determines the maximum input current limit, if the exter-
nal adapter is recognized as a USB charger or USB 2.0
device. The MAX8895_ then initiates enumeration and
determine the maximum input current limit according to
Figure 13.
Low-Power Mode
Driving STDBY high disables the charger as well as
VSYS_, to reduce the input current drawn from VBUS_.
The current drawn in this mode is less than 500FA for the
MAX8895V/MAX8895W/MAX8895X and 2.5mA for the
MAX8895Y. In this mode, the D+ and D- lines become
high impedance. When STDBY is high, VSYS_ is regulated
to 50mV (typ) below VBAT_.
USB Suspend
According to the USB rev 2.0 specification, when a USB
host stops sending traffic for at least 10ms to a peripher-
al (MAX8895_), the peripheral must enter a power-down
state called SUSPEND. Once suspended, the peripheral
must have enough of its internal logic active to recognize
when the host resumes signaling, or if enabled, for gen-
erating remote wake-up.
The MAX8895_ enters SUSPEND state in two ways:
U MAX8895V/MAX8895W/MAX8895X: When no activi-
ty is present on D+/D- for 10ms (max), the MAX8895V/
MAX8895W/MAX8895X automatically enters sus-
pend mode to be compliant with USB specification.
The MAX8895V/MAX8895W/MAX8895X only enters
suspend mode if SUS_EN is pulled high. When
entering suspend mode the MAX8895V/MAX8895W/
MAX8895X disables the charger as well as VSYS_
to reduce the input current drawn from VBUS_. The
current drawn in this mode is less than 500FA for the
MAX8895V/MAX8895W/MAX8895X, ensuring that the
device is compliant with USB specification. In sus-
pend state the bus is IDLE: D+ is low and D- is kept
high by the MAX8895V/MAX8895W/MAX8895X pul-
lup resistor. When in suspend mode, VSYS_ is pow-
ered from VBAT_. When entering automatic suspend
mode, the FLT output is pulled low as an indication
that the charger is disabled.
U MAX8895Y: When no activity is present on D+/D- for
10ms (max), the MAX8895Y automatically enters
suspend mode to be compliant with USB specifica-
tion. When entering suspend mode, the MAX8895Y
disables the charger as well as VSYS_ to reduce the
input current drawn from VBUS_. The current drawn in
this mode is less than 2.5mA, ensuring that the device
is compliant with the USB specification.
In suspend state, the bus is IDLE: D- is low and D+ is
kept high by the MAX8895Y pullup resistor. When in
suspend mode, VSYS_ is powered from VBAT_. When
entering automatic suspend mode, the FLT output is
pulled low as an indication that the charger is disabled.
Figure 13. Flow Chart for Enumeration Process
ILIM = 500mA
SEND CONNECT
ENUMERATION INITIATED
RETURN TO MAIN LOOP
NO
NO
YESYES
YES
YES
IC IS IN
CONFIGURED
STATUS
ENUM_500mA
ENUM_100mA
t < tENUM
DELAY tENU_FAULT
DISABLE
DM_PU (MAX8895V/MAX8895W/
MAX8895X)
DP_PU (MAX8895Y)
ILIM = 100mA ENABLE
DM_PU (MAX8895V/MAX8895W/
MAX8895X)
DP_PU (MAX8895Y)
IC IS IN
CONFIGURED
STATUS
NO
YES
t < tENUM
DISABLE DM_PU
DELAY tENU_FAULT
27Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Figure 14a. Charger Detection Timing Diagram (MAX8895V/MAX8895X)
Figure 14b. USB Detection Timing Diagram (MAX8895V/MAX8895X)
VBUS_
VFLT
INPUT CURRENT LIMIT
CHARGER
(MAX8895V
MAX8895X)
0mA
VDP_SRC
IDM_SINK
ON
OFF
ON
ON
OFF
OFF
LOGIC-LOW
LOGIC-LOW
LOGIC-HIGH
LOGIC-HIGH
DM_PU
D-
0.5mA
DEDICATED CHARGER
OR USB CHARGER
USB CHARGER
DEDICATED CHARGER
USB CHARGER
DEDICATED CHARGER
1500mA
1800mA
tDP_SRC_HC
tDP_SRC_ON
VBUS_
VFLT
INPUT CURRENT LIMIT
USB 2.0
(MAX8895V
MAX8895X)
0mA
VDP_SRC
IDM_SINK
ON
OFF
ON
ON
OFF
OFF
LOGIC-LOW
LOGIC-LOW
LOGIC-HIGH
LOGIC-HIGH
DM_PU
D-
0.5mA
USB 2.0 LOW POWER
USB 2.0 HIGH POWER
100mA
500mA
tDP_SRC_ON
28 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Figure 15a. Charger Detection Timing Diagram (MAX8895Y)
Figure 15b. USB Detection Timing Diagram (MAX8895Y)
VBUS_
VFLT
INPUT CURRENT LIMIT
CHARGER
(MAX8895Y)
0mA
VDP_SRC
IDM_SINK
ON
OFF
ON
ON
OFF
OFF
LOGIC-LOW
LOGIC-LOW
LOGIC-HIGH
LOGIC-HIGH
DP_PU
D-
0.5mA
DEDICATED CHARGER
OR USB CHARGER
USB CHARGER
DEDICATED CHARGER
USB CHARGER
DEDICATED CHARGER
1500mA
1800mA
tDP_SRC_HC
tDP_SRC_ON
VBUS_
VFLT
INPUT CURRENT LIMIT
USB 2.0
(MAX8895Y)
0mA
VDP_SRC
IDM_SINK
ON
OFF
ON
ON
OFF
OFF
LOGIC-LOW
LOGIC-LOW
LOGIC-HIGH
LOGIC-HIGH
DP_PU
D-
0.5mA
USB 2.0 LOW POWER
USB 2.0 HIGH POWER
100mA
500mA
tDP_SRC_ON
29Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Figure 16a. Charger Detection Timing Diagram (MAX8895W)
Figure 16b. USB Detection Timing Diagram (MAX8895W)
VBUS
INPUT CURRENT LIMIT
0mA
VDP_SRC
VDM_SINK
ON
OFF
ON
ON
OFF
OFF
LOGIC-LOW
LOGIC-LOW
LOGIC-HIGH
LOGIC-HIGH
LOGIC-LOW
LOGIC-HIGH
DM_PU
D-
0.5mA 1500mA
1800mA
tDP_SRC_CON
tDP_SRC_ON
DET_DONE
IBUS_DEF
VBUS
INPUT CURRENT LIMIT
0mA
VDP_SRC
VDM_SINK
ON
OFF
ON
ON
OFF
OFF
LOGIC-LOW
LOGIC-LOW
LOGIC-HIGH
LOGIC-HIGH
LOGIC-LOW
LOGIC-HIGH
DM_PU
D+
0.5mA 100mA
500mA
tDP_SRC_CON
tDP_SRC_ON
DET_DONE
IBUS_DEF
USB 2.0 LOW POWER
USB 2.0 HIGH POWER
30 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Wake-Up and USB Resume
The MAX8895_ can wake up four ways while in suspend
mode:
U Logic-high to logic-low transition of STDBY initiating
enumeration.
U MAX8895V/MAX8895W/MAX8895X: If STDBY is
logic-low and SUS_EN is logic-high, the MAX8895V/
MAX8895W/MAX8895X monitor the bus activity on
the D- line. If the host resumes bus activity, the
MAX8895V/MAX8895W/MAX8895X detects this as a
1 to 0 transition on D-. Once this occurs, the device
restarts the oscillator and waits for it to stabilize.
U MAX8895Y: If STDBY is logic-low, the MAX8895Y
monitors the bus activity on the D+ line. If the host
resumes bus activity, the MAX8895Y detects this as a
1 to 0 transition on D+. Once this occurs, the device
restarts the oscillator and waits for it to stabilize.
U Remote wake-up is supported by the MAX8895V/
MAX8895X/MAX8895Y, but the remote wake-up fea-
ture must be enabled by the host during the enu-
meration process. Once suspended, the MAX8895V/
MAX8895X/MAX8895Y look at the state of the battery
charger. If the charger is not in the done state, the
MAX8895V/MAX8895X/MAX8895Y initiate a remote
wake-up signal. If the charger is in the done state, a
remote wake-up is not initiated before the charger is
restarted due to a drop in battery voltage.
U When the MAX8895V/MAX8895X/MAX8895Y initiate
a remote wake-up, they first restart the oscillator and
wait for the oscillator to stabilize, and then send the
remote wake-up event to signal to the host that it
needs to be driven out of the suspend status.
U If RWU is connected to ground and the remote
wake-up feature has not been set by the host during
enumeration, the IC waits tRE_ENUM after entering
suspend mode, then disconnects the pullup resistor
and reinitiates the charger type detection.
Enumeration
USB bus enumeration is an activity that identifies and
assigns unique addresses to devices attached to the
bus. Once the MAX8895_ detects VBUS_ is valid for
TUSB_DB, the MAX8895_ initiates the detection process
to determine the type of device that it is connected to.
If the device type is a USB 2.0 host/hub or USB char-
ger, a 1.5kI pullup resistor is connected between D-
(MAX8895V/MAX8895W/MAX8895X) or D+ (MAX8895Y)
to INT_3V3.
Enumeration is started on the MAX8895V/MAX8895W/
MAX8895X only if ENU_EN is logic-low. If ENU_EN is
logic-high, the MAX8895V/MAX8895W/MAX8895X does
not connect a pullup resistor between D- and INT_3V3,
and the current limit is set to 100mA regardless of the
input type.
When the USB 2.0 host/hub or USB charger detects a
plugged-in peripheral (MAX8895_), it interrogates the
peripheral to learn about its capabilities and require-
ments; and if all is well, configures it to bring it on line.
This process is known as enumeration.
During enumeration the host sends multiple requests to the
device (MAX8895_) asking for descriptors (see Table 2)
that define the device operation.
All the enumeration tasks are self-managed by the
MAX8895_ serial interface engine (SIE) without any pro-
cessor intervention.
The SIE supports the following features:
U USB 2.0 low-speed (1.5Mbps): the MAX8895V/
MAX8895W/MAX8895X pulls D- high to indicate to the
host that it is a low-speed device
U Full-speed (12Mbps) operation: the MAX8895Y pulls
D+ high to indicate to the host that it is a full-speed
device
U Human interface device (HID) in the consumer page
(MAX8895_ does not require any custom drivers)
U 8 bytes end-point zero (control end point)
U 1 byte end-point one (INT-IN end point)
U USB suspend/resume support
U Remote wake-up capability
At the end of enumeration (if successful), the device is
ready to transfer data (if needed) and enabled to sink the
negotiated current from VBUS_.
Figure 17 shows USB bus traffic as captured by a
CATC USB bus analyzer. The traces show a PC (host)
enumerating the peripheral (MAX8895V/MAX8895W/
MAX8895X). Notice that the LS field indicates the
low-speed (1.5Mbps) operation of the MAX8895V/
MAX8895W/MAX8895X.
1) The host uses the default CONTROL end-point EP0
(shown in the “ENDP” boxes) to send a request to the
device. The host initially sends requests to address
0 (shown in the ADDR boxes) to communicate with a
device to which it has not yet assigned a unique address.
31Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Figure 17. USB Bus Traffic: MAX8895V/MAX8895W/MAX8895X Enumeration
TRANSFER
PACKET DIR
CONTROL bREQUEST wVALUE wINDEX DESCRIPTORS TIME TIME STAMPADDR ENDP
0
69 _ >
GET GET_DESCRIPTOR DEVICE TYPE DEVICE DESCRIPTOR 0
L
S0 0x0000 6.80ms
TIMERESET TIME STAMP
52.919ms 00002.2722 173925.881ms
00002.2673 4787
bREQUEST wVALUE wINDEX wLENGTH TIME TIME STAMP
SET_CONFIGURATION NEW CONFIGURATION 10 0x0000 18.999ms 00002.4161 4435
wVALUE wINDEX wLENGTH TIME TIME STAMP
0x0000 0 0x0000 3.000ms
STALL
0x08
D
H_>D
Tp
C
R
I00002.4313 4403
bREQUEST wVALUE wINDEX DESCRIPTORS TIME TIME STAMP
GET_DESCRIPTOR
bREQUEST
0x0A
DEVICE TYPE DEVICE DESCRIPTOR 0x0000 5.986ms 00002.4009 5299
bREQUEST wVALUE wINDEX DESCRIPTORS TIME TIME STAMP
GET_DESCRIPTOR DEVICE TYPE DEVICE DESCRIPTOR 0x0000 6.000ms 00002.3521 4587
bREQUEST wVALUE wINDEX DESCRIPTORS TIME TIME STAMP
GET_DESCRIPTOR CONFIGURATION TYPE, INDEX O CONFIGURATION DESCRIPTOR 0x0000 5.000ms 00002.3569 4579
bREQUEST wVALUE wINDEX DESCRIPTORS TIME TIME STAMP
GET_DESCRIPTOR REPORT_DESCRIPTOR TYPE REPORT DESCRIPTOR 0x0000 15.000ms 00002.4337 4395
bREQUEST wVALUE wINDEX DESCRIPTORS TIME TIME STAMP
GET_DESCRIPTOR CONFIGURATION TYPE, INDEX O4 DESCRIPTORS 0x0000 21.000ms 00002.3609 4563
bREQUEST wVALUE wINDEX DESCRIPTORS TIME TIME STAMP
GET_DESCRIPTOR CONFIGURATION TYPE, INDEX O4 DESCRIPTORS 0x0000 8.000ms 00002.4097 4451
bREQUEST wVALUE wINDEX DESCRIPTORS TIME TIME STAMP
GET_DESCRIPTOR STRING TYPE, LANGID CODES, REQUESTED LANG SUPPORTED LANGUAGE ID 0x0000 5.000ms 00002.3777 4539
bREQUEST wVALUE wINDEX DESCRIPTORS TIME TIME STAMP
GET_DESCRIPTOR STRING TYPE, INDEX 1 USB CHARGER LANGUAGE ID 0x0409 8.000ms 00002.3817 4515
bREQUEST wVALUE wINDEX DESCRIPTORS TIME TIME STAMP
GET_DESCRIPTOR STRING TYPE, INDEX 1 USB CHARGER LANGUAGE ID 0x0409 11.013 ms 00002.3921 4491
bREQUEST wVALUE wINDEX DESCRIPTORS TIME TIME STAMP
GET_DESCRIPTOR STRING TYPE, LANGID CODES REQUESTED LANG SUPPORTED LANGUAGE ID 0x0000 5.000ms 00002.3881 4499
bREQUEST wVALUE wINDEX TIME TIME STAMP
SET_ADDRESS 0x0000
wLENGTH
0NEW ADDRESS 3 46.999ms 00002.3145 4675
TRANSFER CONTROL ADDR ENDP
1SET 0
L
S0
TRANSFER CONTROL ADDR ENDP
2GET 0
L
S0
TRANSFER CONTROL ADDR ENDP
3GET 0
L
S0
TRANSFER CONTROL ADDR ENDP
4GET 0
L
S0
TRANSFER CONTROL ADDR ENDP
5GET 0
L
S0
TRANSFER CONTROL ADDR ENDP
6GET 0
L
S0
TRANSFER CONTROL ADDR ENDP
7GET 0
L
S0
TRANSFER CONTROL ADDR ENDP
8GET 0
L
S0
TRANSFER CONTROL ADDR ENDP
9GET 0
L
S0
TRANSFER CONTROL ADDR ENDP
10 GET 0
L
S0
TRANSFER CONTROL ADDR ENDP
11 GET 0
L
S0
TRANSFER CONTROL ADDR ENDP
12 SET 0
L
S0
TRANSFER CONTROL ADDR ENDP
13 SET 0
L
S0
TRANSFER CONTROL ADDR ENDP
14 GET 0
L
S0
TRANSFER INTERRUPT ADDR ENDP
15 IN 3
L
S1
BYTES TRANSFERRED TIME TIME STAMP
1 8.009ms 00002.4457 4371
BYTES TRANSFERRED TIME TIME STAMP
1 7.991ms 00002.4421 4899
BYTES TRANSFERRED TIME TIME STAMP
1 8.000ms 00002.4585 4339
BYTES TRANSFERRED TIME TIME STAMP
1 8.000ms 00002.4649 4323
BYTES TRANSFERRED TIME TIME STAMP
1 8.009ms 00002.4713 4307
BYTES TRANSFERRED TIME TIME STAMP
1 7.991ms 00002.4777 4843
TRANSFER INTERRUPT ADDR ENDP
16 IN 3
L
S1
TRANSFER INTERRUPT ADDR ENDP
17 IN 3
L
S1
TRANSFER INTERRUPT ADDR ENDP
18 IN 3
L
S1
TRANSFER INTERRUPT ADDR ENDP
19 IN 3
L
S1
TRANSFER INTERRUPT ADDR ENDP
20 IN 3
L
S1
bREQUEST wVALUE wINDEX DESCRIPTORS TIME TIME STAMP
GET_DESCRIPTOR CONFIGURATION TYPE, INDEX O CONFIGURATION DESCRIPTOR 0x0000 5.000ms 00002.4057 4459
32 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Figure 18. USB Bus Traffic: MAX8895Y Enumeration
TRANSFER
1
F
S
TRANSFER
1
F
S
TRANSFER
2
F
S
TRANSFER
3
F
S
TRANSFER
4
F
S
TRANSFER
5
F
S
TRANSFER
6
F
S
TRANSFER
7
F
S
TRANSFER
8
F
S
TRANSFER
9
F
S
TRANSFER
10
F
S
TRANSFER
11
F
S
TRANSFER
12
F
S
TRANSFER
13
F
S
TRANSFER
14
F
S
TRANSFER
15
F
S
TRANSFER
16
F
S
TRANSFER
17
F
S
TRANSFER
18
F
S
TRANSFER
19
F
S
CONTROL
RESET 26.370ms
ADDR ENDP
SET 00
CONTROL ADDR ENDP
SET 00
CONTROL ADDR ENDP
GET 10
CONTROL ADDR ENDP
GET 10
CONTROL ADDR ENDP
GET 10
CONTROL ADDR ENDP
GET 10
CONTROL ADDR ENDP
GET 10
CONTROL ADDR ENDP
GET 10
CONTROL ADDR ENDP
GET 10
CONTROL ADDR ENDP
GET 10
CONTROL ADDR ENDP
GET 10
CONTROL ADDR ENDP
GET 10
CONTROL ADDR ENDP
GET 10
CONTROL ADDR
SET 10
CONTROL ADDR ENDP
SET 10
CONTROL ADDR ENDP
GET 10
INTERRUPT ADDR ENDP
IN 11
INTERRUPT ADDR ENDP
IN 11
INTERRUPT ADDR ENDP
IN 11
INTERRUPT ADDR ENDP
IN 11
bREQUEST wVALUE wINDEX DESCRIPT0RS TIME
GET_DESCRIPTOR CONFIGURATION TYPE 4 DESCRIPTORS 0x0000 8.000ms
wVALUE TIME
NEW CONFIGURATION 1 20.001ms
bREQUEST wVALUE wINDEX DESCRIPTORS TIME
GET_DESCRIPTOR
bREQUEST
SET_CONFIGURATION
STRING TYPE, INDEX 1 STRING: USB CHARGER
LANGUAGE ID 0x0409 30.001ms
DESCRIPTORS TIME
HIDM REPORT DESCRIPTOR 16.001ms
bREQUEST wVALUE wINDEX DESCRIPTORS TIME
GET_DESCRIPTOR
bREQUEST
GET_DESCRIPTOR
DEVICE TYPE
wVALUE
DEVICE TYPE
DEVICE DESCRIPTOR
DESCRIPTORS
DEVICE DESCRIPTOR
0x0000
wINDEX
0x0000
IDLE
6627
6.000ms
bREQUEST wVALUE wINDEX DESCRIPT0RS TIME
GET_DESCRIPTOR CONFIGURATION TYPE CONFIGURATION DESCRIPTOR 0x0000 5.000ms
bREQUEST wVALUE wINDEX
0x0A 0x0000 0x0000
bREQUEST wVALUE wINDEX DESCRIPT0RS TIME
GET_DESCRIPTOR CONFIGURATION TYPE 4 DESCRIPTORS 0x0000 9.000ms
bREQUEST wVALUE wINDEX DESCRIPT0RS TIME
GET_DESCRIPTOR CONFIGURATION TYPE, INDEX O CONFIGURATION TYPE, INDEX O
0x0000 8.000ms
bREQUEST wVALUE wINDEX STALL TIME
GET_DESCRIPTOR DESCRIPTOR TYPE 0X06, INDEX 0 0x78 0x0000 3.001ms
STALL TIME
0x78 3.000ms
bREQUEST wVALUE wINDEX DESCRIPT0RS TIME
GET_DESCRIPTOR STRING TYPE. LANGID CODES REQUESTED 0x0409
LANGUAGE ID 0x0000 5.000ms
bREQUEST wVALUE wINDEX DESCRIPT0RS TIME
GET_DESCRIPTOR STRING TYPE, LANGID CODES REQUESTED 0x0409
LANGUAGE ID 0x0000 5.001ms
bREQUEST wVALUE wINDEX DESCRIPT0RS TIME
GET_DESCRIPTOR STRING TYPE, INDEX 1 STRING: USB CHARGER
LANGUAGE ID 0x0409 8.000ms
bREQUEST wVALUE TIME
SET_ADDRESS NEW ADDRESS 147.002ms
bREQUEST wVALUE wINDEX
GET_DESCRIPTOR DESCRIPTOR TYPE 0x22, INDEX 0 0x0000
BYTES TRANSFERREDTIME
132.001ms
BYTES TRANSFERRED TIME
132.001ms
BYTES TRANSFERRED TIME
132.001ms
BYTES TRANSFERRED TIME
10ns
bREQUEST wVALUE wINDEX DESCRIPT0RS TIME
GET_DESCRIPTOR DEVICE TYPE DEVICE DESCRIPTOR 0x0000 6.001ms
33Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Table 2. Device Descriptor
2) The host begins by sending a Get_Descriptor_Device
request (Transfer 0 in Figure 16). It does this to deter-
mine the maxPacketSize of the device’s EP0 buffer
(for the MAX8895V/MAX8895X, it is 8 bytes). The host
then resets the device by issuing a bus reset (packet
69).
3) In transfer 1, the host assigns a unique address to
the peripheral by using the Set_Address request.
The assigned address depends on how many other
USB devices are currently attached to the host.
In this case, the address assigned to our periph-
eral device (MAX8895V/MAX8895X) is 3. Thereafter,
the MAX8895V/MAX8895X respond only to requests
directed to address 3. This address remains in force
until the host does a bus reset or the device is dis-
connected. Notice that the peripheral address field
(ADDR) in the bus trace changes from 0 to 3 after
transfer 1.
4) In transfers 2 to 11, the host asks for various descrip-
tors. The device FSM needs to determine from the
eight setup bytes which descriptor to send, use this
information to access one of several character arrays
(ROMs) representing the descriptor arrays.
5) In transfer 12, the host requests the device to use the
specified configuration (1) and the device enters the
configured state.
According to the USB 2.0 specification, a bus powered
device can be either low power (it may draw no more
than 100mA) or high power (it may draw no more than
500mA).
All devices must default to low power. The transition to
high power is under software control (running on the
host side). It is the responsibility of software to ensure
adequate power is available before allowing devices to
consume high-power.
The MAX8895_ initiates enumeration by asking for
500mA of current. If the MAX8895_ does not enter con-
figured status before the tENUM (10s, typ), it interprets
this as an indication that the host is not able to support
the requested current. The MAX8895_ disconnects
the pullup resistor on D- (MAX8895V/MAX8895X)/D+
(MAX8895Y), wait for tENU_FAULT, and then retry to enu-
merate, but now as a low current device (100mA). If the
MAX8895_ has still not reached the configured status
after tENUM, the MAX8895_ assumes that either the host
is nonresponsive or a wrong adapter type is detected.
In this case, the MAX8895_ disconnects the pullup
resistor on D- (MAX8895V/MAX8895W/MAX8895X)/D+
(MAX8895Y) and wait for tENU_FAULT + tFAULT before
starting the adapter detection process again.
Figure 18 shows the USB traffic captured during the
MAX8895Y enumeration. Notice the field FS indicates the
full-speed (12Mbps) operation of the MAX8895Y.
FIELD LENGTH
(bits)
OFFSET
(bits) DECODED HEXVALUE DESCRIPTION
bLength 8 0 0x12 0x12 Descriptor size is 18 bytes
bDescriptorType 8 8 0x01 0x01 Device descriptor type
bcdUSB 16 16 0x0200 0x0200 Device compliant to the USB specification version 2.0
bDeviceClass 8 32 0x00 0x00 Each interface specifies its own class information
bDeviceSubClass 8 40 0x00 0x00 Each interface specifies its own subclass information
bDeviceProtocol 8 48 0x00 0x00 No protocols the device basis
bMaxPacketSize0 8 56 0x08 0x08 Maximum packet size for end-point zero is 8
idVendor* 16 64 — — Vendor ID is 2922: Maxim Integrated Products
idProduct* 16 80 0x5346 0x5346 Product ID is 21318
bcdDevice 16 96 0x1234 0x1234 The device release number is 1.00
iManufacturer 8 112 0x00 0x00 The device does not have the string descriptor
describing the manufacturer
iProduct 8 120 0x01 0x01 The product stringed descriptor index is 1
iSerialNumber 8 128 0x00 0x00 The device does not have the string descriptor
describing the serial number
bNumConfigurations 8 136 0x01 0x01 The device has 1 possible configuration
34 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Smart Power Selector
The Smart Power Selector seamlessly distributes power
between the external VBUS_ input, the battery (VBAT_),
and the system load (VSYS_). See Figure 19. The Smart
Power Selector basic functions are:
U With both an external adapter and battery connected:
a. When the system load requirements are less than
the input current limit, the battery is charged with
residual power from the input.
b. When the system load requirements exceed the
input current limit, the battery supplies supplemental
current to the load.
U When the battery is connected and there is no external
power input, the system is powered from the battery.
U When an external power input is connected and there
is no battery, the system is powered from VBUS_.
If the junction temperature starts to get too hot (+110NC
typ), the charging rate is reduced. If this is not sufficient
to cool down the MAX8895_, the input current limit is
then reduced.
System Load Switch
An internal 55mI (typ) MOSFET connects VSYS_ to
VBAT_ (Q2, Figure 19) when no voltage source is avail-
able at VBUS_ and VBAT_ is above the battery UVLO
threshold. When an external source is detected at
VBUS_, this switch controls the charging of VBAT_ and
VSYS_ is powered from the valid input source through the
input current limiter.
The VSYS_ - VBAT_ switch also prevents VSYS_ from fall-
ing below VBAT_ when the system load exceeds the input
current limit. If that should happen, VSYS_ is allowed to
drop to VBAT_. At this point, the VSYS_ - VBAT_ switch
turns on so that the battery supplies additional ISYS_
load current. If the system load continuously exceeds the
input current limit, then the battery does not charge, even
though external power is connected. This is not expected
to occur in most cases, since high loads usually occur
only in short peaks. During these peaks, battery energy is
used, but at all other times the battery charges.
Input Limiter
The input limiter distributes power from the external
adapter to the system load and battery charger. In addi-
tion to the input limiter’s primary function of passing
power to the system and charger, it performs several
additional functions to optimize use of available power.
U Input Voltage Limiting: If the VBUS_ input voltage
is above the overvoltage threshold (VBUS_OVP), the
MAX8895_ enters overvoltage lockout (OVL). OVL
protects the MAX8895_ and downstream circuitry
from high-voltage stress up to 16V at VBUS_. In OVL,
VINT_3V3 remains on, the input switch that sees
overvoltage (Q1, Figure 19) opens, FLT is pulled low,
and UOK, CHG, DET_DONE, and PREQ become
high-impedance. In OVL, the charger turns off. The
VBAT_ - VSYS_ switch (Q2, Figure 19) closes, allowing
the battery to power VSYS_. VBUS_ is also invalid if it
is less than VBAT_, or less than the USB undervoltage
threshold (VBUS_UVLO_F). With an invalid input volt-
age, VSYS_ connects to BAT_ through a 55mI (typ)
switch (Q2, Figure 19).
U Input Overcurrent Protection: The current at VBUS_
is limited to prevent input overload. This current limit is
automatically selected to match the capabilities of the
adapter source, whether it is a 100mA or 500mA USB
2.0 source, or 500mA to 1.8A for a dedicated adap-
tor or USB charger. When the load exceeds the input
current limit, VSYS_ drops to 50mV (typ) below VBAT_
and the battery supplies supplemental load current.
*Contact factory for specific vendor ID and product ID.
Figure 19. Smart Power Selector Block Diagram Figure 20. VSYS_ Regulation
VBUS_
VBAT_
CHARGE
CURRENT
Q2 CHARGE
AND SYS LOAD
SWITCH
LOAD
CURRENT
GND
Q1
VSYS_
SYSTEM
LOAD
SYSTEM
LOAD
1-CELL Li+
MAX8895V
MAX8895W
MAX8895X
MAX8895Y
3.4V (min)
TIME
140mV
VBAT_
VSYS_
35Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Figure 21. Adaptive Input Current-Limit Regulation Loop
U Thermal Limiting: The MAX8895V/MAX8895X/
MAX8895Y reduce input current by 5%/NC when its
die temperature exceeds TDIE_LIM (+110NC typ). The
system load (VSYS_) has priority over charger cur-
rent, so the input current is first reduced by lowering
the charge current. If the junction temperature still
reaches TDIE_LIM +20NC in spite of charge current
reduction, no input VBUS_ current is drawn, the bat-
tery supplies the entire system load, and VSYS is
regulated at 50mV (typ) below VBAT_.
Note: The on-chip thermal limiting circuitry is not
related to, and operates independently from, the
thermistor input.
U Adaptive Battery Charging: While the system is
powered from VBUS_, the charger draws power from
VSYS_ to charge the battery. If the combined load
between the charger and system exceeds the input
current limit, an adaptive charger control loop reduces
charge current to prevent the VSYS_ voltage from col-
lapsing.
Regulation Threshold
The MAX8895_ always regulates VSYS_ to 140mV (typ)
above VBAT_ with a minimum voltage of 3.4V regardless
of what device is connected. The 3.4V minimum voltage
regulation reduces the ripple on VSYS_ during peak load
conditions where the input current limit is tripped.
Input Current Limit
If the connected adapter is a USB 2.0 device the input
current limit is set by default to 100mA.
If ENU_EN is connected to INT_3V3 or driven logic-high
for the MAX8895V/MAX8895X/MAX8895Y, the charger
input current limit remains at 100mA. If ENU_EN is set to
logic-high for the MAX8895W the charger’s input current
limit is determined by the logic state of IBUS_DEF.
When ENU_EN is connected to AGND, automatic enu-
meration is initiated. The MAX8895_ proceeds to deter-
mine if the external USB device is a low- or high-power
device and set the input current limit to 100mA or
500mA, respectively. For a dedicated charger or USB
charger, the current limit is determined by loading the
adapter. When the adapter’s output voltage starts to
collapse, it is an indication that the current limit of the
device is reached.
The MAX8895_ set the input current limit to regulate
VBUS to VSYS +440mV (typ). This ensures that the power
dissipation in the MAX8895_ is kept to a minimum, and
at the same time, ensuring that the adapter’s current
capability is fully utilized. When a dedicated charger is
detected, the input current limited is limited by the adap-
tive input current limit. In this mode, it is up to the adapter
to limit the maximum current, which is 1.85A for a dedi-
cated charger and 1.5A for a USB charger, according to
the USB charging specification.
TIME
IIILM 500mA
3.4V (min)
ADAPTER TYPE DETECTION ADAPTIVE INPUT CURRENT-LIMIT REGULATION
440mV (typ)
140mV (typ)
VBUS_
VBAT_
VSYS_
36 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
If the adapter output (VBUS) starts to drop below VSYS
- 440mV (typ), the input current limit function adap-
tively decreases the input current limit to ensure that the
adapter is not overloaded. When the input current limit
is reached, the first action taken by the MAX8895_ is to
reduce battery charge current. If, after the charge cur-
rent is reduced to 0mA, the load at ISYS still exceeds the
input current limit, VSYS begins to fall. When VSYS drops
to 50mV below VBAT, the VSYS - VBAT switch turns on,
using battery power to support the system load during
the load peak. See Figure 21 for more information.
Power Monitor Output (UOK)
UOK is an open-drain output that pulls low when the
VBUS_ input has valid power.
The UOK monitor has several different thresholds,
depending on what type of adapter detected. The differ-
ent thresholds are as follows:
U The initial detection threshold allows all types of
adapters to be detected on VBUS_. Once the type
of adapter is determined, the UVLO threshold is
changed.
U For any USB 2.0 device the UVLO thresholds are set
to be compliant with USB specifications.
U For a dedicated charger, the UVLO (falling) threshold
is lowered to VSYS_ + 50mV (typ) to allow for support-
ing collapsing charger types, allowing the MAX8895_
to operate with lower power dissipation.
Note that since the VBUS_ UVLO threshold is changed
after initial detection of the device type, there are condi-
tions where the MAX8895_ can toggle between VBUS_
valid and not valid. This is an indication that the adapter
is not within the specified limits.
See Table 3 for more information.
Table 3. UOK Monitor Thresholds
Figure 22. Charging States
TIME
TOP-OFF MAINTENANCE
CHARGE
PRECHARGE
t < tPCHG t < tFCHG t = tMTCHG
FAST-CHARGE CHARGE
DONE
IPCHG
IFCHG
0.6 x IFCHG
ICHG_DONE
VCHG_REG
VBAT_FCHG_R
VBAT_PCHG_R
THRESHOLDS UVLO OVLO (V)
Initial VBUS_ detection 4.0V (typ), rising
6.9
For USB 2.0 low power 3.9V (typ), falling
For USB 2.0 high power 4.1V (typ), falling
For dedicated charger to USB charger VSYS_ + 50mV (typ), falling
37Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Figure 23. Charger Flow Chart
Soft-Start
To prevent input transients that can cause instability in
the USB power source, the rate of change of input cur-
rent and charge current is limited. When a valid USB 2.0
input is connected, the input current limit is ramped from
0 to 100mA in 50Fs. Once enumeration is ended, the cur-
rent can be ramped to 500mA or to the new input current
limit value in 50Fs.
When the charger is enabled, the charge current ramps
from zero to the final value in 1.5ms (typ). Charge cur-
rent also ramps when transitioning to fast-charge from
prequalification and when changing the USB charge
current from 100mA to 500mA.
Note: There is no di/dt limiting if IISET is changed sud-
denly using a switch at RISET.
Battery Charger
The battery charger has five different states of operation
(see Figures 22 and 23):
U Precharge: When the battery voltage is below
VBAT_PCHG_R. In this state, the battery is charged
at maximum IPCHG. If the IPCHG > ILIM, then the
precharging current is determined by the ILIM (input
current limit). Charging a Li+ battery at high charging
current when it is fully discharged can cause the bat-
tery to become unstable and potentially dangerous.
Charging at high charging rates on a fully discharged
battery can also reduce life cycles of the Li+ battery.
U Fast-charge: In fast-charge mode, the charging cur-
rent is set to maximum IFCHG. The actual charging
current is determined by ILIM - ISYS_.
U Top-off charge: In top-off mode, the battery voltage
has almost reached the set point (VBAT_FCHG_R). The
charging current is reduced in this mode to prevent
overcharging the battery, and also to minimize the
power dissipation in the battery.
U Maintenance charge: The charger enters this mode
when the charging current has dropped below the
ICHG_DONE threshold. The charger continues to
charge for tMTCHG time to ensure the battery is fully
charged before the charger is disabled.
U Charge done: Charger is disabled and only en-
gages again if the battery voltage drops below the
VBAT_RECHG threshold.
UOK = HIGH-Z
(CHG = HIGH-Z)
FLT = HIGH-Z
ICHG = 0mA
( ) MAX8895V/MAX8895X/
MAX8895Y ONLY
NO VALID VBUS
VBUS_UVLO > VBUS_ OR
VBUS_OVP < VBUS_
FROM ANY STATE
CEN = HIGH
FROM ANY STATE
VBUS_UVLO < VBUS_ < VBUS_OVP
tCHG_TIMER >
tPCHG
tCHG_TIMER >
tFCHG
tCHG_TIMER > tFCHG
tCHG_TIMER > tMTCHG TTHM_COLD > TA OR
TTHM_HOT < TA
TTHM_COLD < TA
< TTHM_HOT
UOK = LOW
(CHG = HIGH-Z)
FLT = LOW
ICHG = 0mA
CHARGER OFF
PREQUAL
UOK = LOW
PREQ = LOW
(CHG = LOW)
FLT = HIGH-Z
ICHG = IPCHG
UOK = LOW
(CHG = LOW)
FLT = HIGH-Z
*ICHG = IFCHG
FAST-CHARGE FAULT
UOK = LOW
(CHG = HIGH-Z)
FLT = LOW
ICHG = 0mA
TOP-OFF
CHARGE
UOK = LOW
(CHG = LOW)
FLT = HIGH-Z
ICHG = IFCHG/2
UOK = LOW
(CHG = HIGH-Z)
FLT = HIGH-Z
ICHG < ICHG_DONE
DONE
UOK = LOW
(CHG = HIGH-Z)
FLT = HIGH-Z
ICHG = 0mA
TEMPERATURE
SUSPENSE
UOK = LOW
(CHG = HIGH-Z)
FLT = HIGH-Z
ICHG = 0mA
CHARGE TIMER PAUSED
CEN = LOW
RESET CHARGE TIMER
VBAT_ > VBAT_PCHG_R
RESET CHARGE TIMER
VBAT_ < VBAT_PCHG_F
RESET CHARGE TIMER
ICHG < ICHG_DONE AND
IBUS < ILIM
tDIE < tDIE_LIM
RESET CHARGE TIMER
ICHG R ICHG_DONE
RESET CHARGE
TIMER
VBAT_ < VBAT_PCHG_F
RESET CHARGE
TIMER
FROM ANY CHARGING STATE
*CHARGE TIMER
SLOWED DOWN BY X2
IF: ICHG < IFCHG/2
AND PAUSED IF:
ICHG < IFCHG/5
VBAT_ > VBAT_FCHG_R
VBAT_ < VBAT_FCHG_F
VBAT_ > VBAT_RECHG
RESET CHARGE
TIMER
MAINTENANCE
CHARGE
38 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Charge Enable (CEN)
When CEN is logic-low, the battery charger is enabled.
When CEN is logic-high, the battery charger is disabled.
CEN does not affect VSYS_. In many systems, there is
no need for the system controller (typically a micro-
processor) to disable the battery charger because the
MAX8895_ Smart Power Selector circuitry independently
manages charging and USB-battery power handover. In
these situations, CEN may be connected to ground.
Setting Charge Current (ISET)
ISET adjusts the charge current to match the capacity of
the battery. The maximum charging current can be fixed
by connecting ISET to INT_3V3 or can be adjusted by
connecting ISET to ground through a resistor. When ISET
is connected to ground through a resistor the maximum
charging current is determined using the following for-
mula:
FCHG ISET
3000
IR
=
where RISET is a resistor from ISET to ground.
Determine the IFCHG value by considering the charac-
teristics of the battery. It is not necessary to limit charge
current based on the capabilities of the expected adapt-
er input, the system load, or thermal limitations of the
PCB. The MAX8895_ automatically adjusts the charging
algorithm to accommodate these factors.
Monitoring Charge Current (ISET)
In addition to setting charge current, ISET can also be
used to monitor the actual current charging the battery.
The ISET output voltage is:
ISET
CHG ISET
V
I 2000
R
= ×
where:
ICHG is the actual battery charge current, RISET is a
resistor from ISET to ground.
A 1.5V output indicates the battery is being charged
at the maximum fast-charge current (IFCHG). 0V indi-
cates no charging. The ISET voltage is also used by the
charger control circuitry to set and monitor the battery
current. Avoid adding more than 10pF of capacitance
directly to the ISET pin. If filtering of the charge current
monitor is necessary, add a resistor of 100kI or more
between ISET and the filter capacitor to preserve char-
ger stability.
If the maximum charge current (IFCHG), is set to the
default value, the current monitor function is not available.
Charge Termination (IDN)
When the charge current falls to the termination thresh-
old and the charger is in voltage mode, charging is com-
plete. Charging continues for a time period defined by
the tCHG_DONE and then enters the DONE state where
charging stops.
The IDN input adjusts the charge current termination
threshold. The termination threshold can be fixed by
connecting IDN to INT_3V3 or can be adjusted by con-
necting IDN to ground through a resistor. When IDN is
connected to ground through a resistor, the charge done
threshold is determined using the following formula:
TERM IDN
2400
IR
=
where RIDN is a resistor from IDN to ground.
Note that if charge current falls to ITERM as a result of
the input or thermal limiter, the charger does not enter
the DONE state. For the charger to enter DONE, charge
current must be less than ITERM, the charger must be
in voltage mode, and the input or thermal limiter must
not be reducing charge current. The charger exits the
DONE state and fast-charge resumes if the battery volt-
age subsequently drops below VBAT_RECHG or if CEN is
cycled. Connecting IDN to INT_3V3 selects the default
termination current threshold.
Figure 24. Monitoring Charge Current with the ISET Voltage
CHARGEDISCHARGE
MONITORING THE BATTERY CHARGE
CURRENT USING VISET
1.5V
0V
0A
BATTERY
CHARGE
CURRENT (A)
OR
= IFCHG
1.5V
RISET
=x 2000
VISET
(V)
39Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Charge Status Outputs
Charge Output (CHG) (MAX8895V/MAX8895X/
MAX8895Y Only)
CHG is an active-low, open-drain output that is driven
low during charging. CHG is logic-low when the battery
charger is in fast-charge and top-off states. When charge
current falls to the charge termination threshold and the
charger is in voltage mode CHG goes high impedance.
CHG holds its current state if the thermistor causes the
charger to enter temperature suspend mode. When
the MAX8895V/MAX8895X/MAX8895Y are used with a
microprocessor, connect a pullup resistor between CHG
and the logic I/O voltage to indicate charge status to the
microprocessor. Alternatively, CHG can sink up to 20mA
for an LED indicator.
Prequalification Output (PREQ)
(MAX8895V/MAX8895X/MAX8895Y Only)
PREQ is an active-low, open-drain output that is driven
low when the charger is in prequalification state. When
the MAX8895V/MAX8895X/MAX8895Y are used in con-
junction with a microprocessor, connect a pullup resis-
tor between PREQ and the logic I/O voltage to indicate
charge status to the microprocessor. Alternatively, PREQ
can sink up to 20mA for an LED indicator.
Fault Output (FLT) and Charge Timer (CT)
FLT is an active-low, open-drain output that is driven
low during a battery fault. The fault state occurs when
either the prequalification or fast-charge timer expires.
The prequalification and fast-charge fault timers are set
by CCT:
CT
PREQUAL
C
t 16min 0.068 F
= × F
CT
FCHG
C
t 100min 0.068 F
= × F
While in fast-charge mode, a large system load or device
self-heating may cause the MAX8895_ to reduce charge
current. Under these circumstances, the fast-charge timer
adjusts to ensure that adequate charge time is still
allowed. Consequently, the fast-charge timer is slowed
by 2x if charge current is reduced below 50% of the pro-
grammed fast charge level. If charge current is reduced
to below 20% of the programmed level, the fast-charge
timer is paused. The fast-charge timer is not adjusted if the
charger is in voltage mode where charge current reduces
due to current tapering under normal charging.
To exit a fault state, toggle CEN or remove and recon-
nect the VBUS_ input source. Note: A thermistor out-of-
range or on-chip thermal limit conditions are not consid-
ered faults. When the MAX8895V/MAX8895X/MAX8895Y
are used in conjunction with a microprocessor, connect
a pullup resistor between FLT and the logic I/O voltage to
indicate fault status to the microprocessor. Alternatively,
FLT can sink up to 20mA for an LED indicator.
CHG_TYPE Output (MAX8895W Only)
The output CHG_TYPE is used to indicate the type of
interface detected. If CHG_TYPE output is logic level
low the input current limit is set to 100mA or less. If
CHG_TYPE output is logic level high the input current
limit is set to 500mA or greater.
DET_DONE Output (MAX8895W Only)
DET_DONE is an active low, open-drain output that
is driven low once adapter detection is complete.
DET_DONE is high impedance in suspend mode.
IBUS_DEF Output (MAX8895W Only)
The IBUS_DEF input is only valid when ENU_EN is set
to logic-high activating the adapter type detection. If
the adapter type is detected as a USB 2.0 device, the
input current limit is set to the programmed value and
the MAX8895W does not initiate USB enumeration. If
IBUS_DEF is connected to ground or logic level low, the
input current limit is set to 100mA. If IBUS_DEF is con-
nected to INT_3V3 or logic level high, the input current
limit is set to 500mA.
Thermistor Input (THM)
The THM input connects to an external negative tem-
perature coefficient (NTC) thermistor to monitor battery
or system temperature. Charging is suspended when
the thermistor temperature is out of range. The charge
timers are suspended and hold their state, but no fault is
indicated. When the thermistor comes back into range,
charging resumes and the charge timer continues from
where it was at previously. Connecting THM to AGND
disables the thermistor monitoring function.
Since the thermistor monitoring circuit employs an exter-
nal bias resistor from THM to VINT_3V3 (RTB, Figure 25),
the thermistor is not limited only to 10kI (at TA = +25NC).
Any resistance thermistor can be used as long as the
value of RTB is equivalent to the thermistor’s TA = +25NC
resistance. For example, with a 10kI at TA = +25NC
thermistor, use 10kI at RTB, and with a 100kI at TA =
+25NC thermistor, use 100kI.
For a typical 10kI at TA = +25NC thermistor and a 10kI
RTB resistor, the charger enters a temperature suspend
state when the thermistor resistance falls below 3.97kI
(too hot) or rises above 28.7kI (too cold). These limits
40 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
correspond to a 0NC to +50NC range when using a 10kI
NTC thermistor with a beta of 3500. The general relation
of thermistor resistance to temperature is defined by the
following equation:
11
T 273 298
T 25
RR e
β−
+
= ×
where:
RT = The resistance (I) of the thermistor at temperature
T in NC.
R25 = The resistance (I) of the thermistor at TA = +25NC.
A = The material constant of the thermistor which typi-
cally ranges from 3000K to 5000K.
T = The temperature of the thermistor in NC.
Table 4 shows the MAX8895_ THM temperature limits for
different thermistor material constants.
Figure 25. Thermistor Monitor Circuitry
Table 4. Fault Temperatures for Different Thermistors
MAX8895V
MAX8895X
MAX8895Y
ALL COMPARATORS
60mV HYSTERESIS
COLD
THERMISTOR
CIRCUITRY
CEN
THM
AGND
0.74 x
VINT_3V3
0.28 x
VINT_3V3
0.03 x
VINT_3V3
HOT
ENABLE THM
THM OUT OF
RANGE
DISABLE
CHARGER
ALTERNATE THERMISTOR
CONNECTION
RTB
RT
RT
RTS
RTP
THERMISTOR ß (K) 3000 3250 3500 3750 4250
RTB (kI) (Figure 22) 10 10 10 10 10
Resistance at +25NC (kI)10 10 10 10 10
Resistance at +50NC (kI)4.59 4.30 4.03 3.78 3316
Resistance at 0NC (kI)25.14 27.15 29.32 31.66 36.91
Nominal hot trip temperature (NC) 55 53 50 49 46
Nominal cold trip temperature (NC) -3 -1 0 2 4.5
41Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Some designs may require other thermistor temperature
limits. The threshold adjustment can be accommodated
by changing RTB, connecting a resistor in series and/or
in parallel with the thermistor, or using a thermistor with
different A. For example, a TA = +45NC hot threshold
and TA = 0NC cold threshold can be realized by using
a thermistor with a A of 4250 and connecting a 120kI
resistor in parallel. Since the thermistor resistance near
TA = 0NC is much higher than it is near TA = +50NC, a
large parallel resistance lowers the cold threshold, while
only slightly lowering the hot threshold. Conversely, a
small-series resistance raises the cold threshold, while
only slightly raising the hot threshold. Raising RTB low-
ers both the hot and cold thresholds, while lowering RTB
raises both thresholds.
Thermal Shutdown
Thermal shutdown limits total power dissipation in the
MAX8895_. When the junction temperature exceeds
+160NC (typ), the device turns off, allowing the MAX8895_
to cool. The MAX8895_ turn on and begin soft-start after
the junction temperature cools by 20NC (typ). This results
in a pulsed charge current during continuous thermal-
overload conditions.
External Clock (MAX8895Y)
The MAX8895Y includes full-speed USB 2.0 compat-
ibility. USB 2.0 full speed requires that the system clock
of the transceiver is within Q2500ppm, over temperature,
aging, etc. Therefore, the MAX8895Y requires an exter-
nal resonator or clock source to stay within this limit.
The MAX8895Y local oscillator and internal digital clocks
are derived from the reference clock at the XIN input.
External Crystal/Ceramic Resonator
(MAX8895Y)
XIN and XOUT are used to interface to an external
12MHz crystal or ceramic resonator. Connect a 33pF
load capacitor from both XIN/XOUT to ground.
Requirements for the external resonator/crystal for
MAX8895Y:
Frequency: 12MHz Q0.25%
CLOAD: 33pF Q20%
Drive level: 200FW
Series resonance resistance: 60I (maximum), 30I
(typical)
Note: Series resonance resistance is the resistance
observed when the resonator is in the series resonant
condition. This is a parameter often stated by quartz crys-
tal vendors and is called R1. When a resonator is used in
the parallel resonant mode with an external load capaci-
tance, as is the case with the MAX8895Y oscillator circuit,
the effective resistance is sometimes stated. The effective
resistance at the loaded frequency of oscillation is:
2
O
EFF LOAD
C
R R1 1 C
= ×+
where:
R1 = Series resonance resistance
CO = Crystal capacitor
CLOAD = External load capacitance
For typical CO and CLOAD values, the effective resis-
tance can be greater than R1 by a factor of 2.
External Clock (MAX8895Y)
The MAX8895Y can also be driven from an external clock.
The MAX8895Y accepts an external clock input at XIN.
The external clock can either be a digital level square
wave or sinusoidal and this may be directly coupled to XIN
without the need for additional components. If the peaks of
the reference clock are above VINT_3V3 or below ground,
the clock signal must be driven through a DC-blocking
capacitor (approximately 33pF) connected to XIN.
The external clock source can either be enabled using
the UOK or INT_3V3 signals depending on if the clock
source is active-low or active-high enabled.
If the INT_3V3 rail is used, ensure that no significant load
is taken from this output since this affects the perfor-
mance of the MAX8895Y.
Clock Timing Accuracy (MAX8895Y)
USB 2.0 specification requires the system clock to be within
Q2500ppm over temperature, aging, etc. It is recommended
to use a clock source with tighter initial accuracy to ensure
that over time the accuracy of Q2500ppm is still valid.
ESD Protection
D+, D-, and VBUS_ possess extra protection against
static electricity to protect the devices up to Q8kV (HBM).
The ESD structures withstand high ESD in all operating
modes: normal operation, suspend mode, and powered
down. VBUS_ requires 1FF ceramic capacitors connect-
ed to ground as close as possible to the pins.
42 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
ESD Test Conditions
ESD performance depends on a variety of conditions.
Contact Maxim for a reliability report that documents
test setup, test methodology, and test results. Figure 26
shows the Human Body Model, and Figure 27 shows
the current waveform generated when discharged into a
low impedance. This model consists of a 100pF capaci-
tor charged to the ESD voltage of interest, which then
discharges into the test device through a 1.5kI resistor.
Applications Information
Capacitor Selection
Ceramic X5R or X7R dielectric capacitors are recommend-
ed for best operation. When selecting ceramic capacitors
in the smallest available case size for a given value, ensure
that the capacitance does not degrade significantly with
DC bias. Generally, ceramic capacitors with high values
and very small case size have poor DC bias characteris-
tics. Evaluate capacitors carefully before using.
Ground Connections
Minimize trace lengths between the bypass capacitors
and ground. Use separate digital/power ground (DGND)
and analog ground (AGND) copper areas, and connect
them together at the negative terminal of the battery.
The pins and/or external components for KB_TM, crystal
load capacitors, ISET, IDN, CT, thermistor, and INT_3V3
should connect to a quiet analog ground. All other
ground connections should connect to DGND.
Recommended PCB Layout
and Routing
Place all bypass capacitors for INT_3V3, VBUS_, VBAT_,
and VSYS_ as close as possible to the device. Connect
the battery to BAT_A and BAT_B as close as possible to
the device to provide accurate battery voltage sensing.
Make all high-current traces short and wide to minimize
voltage drops.
When using the MAX8895Y, place the external crystal and
load capacitors as close as possible to the MAX8895Y.
The crystal and load capacitors should be kept as far
away as possible from the D+/D- traces.
Refer to the MAX8895 Evaluation Kit for an exam-
ple layout. The MAX8895 Evaluation Kit supports the
MAX8895V/MAX8895X and MAX8895Y.
Figure 26. Human Body Test Model Figure 27. Human Body Model Current Waveform
CHARGE-CURRENT
LIMIT RESISTOR
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
CS
100pF
RD
1.5kI
DEVICE
UNDER
TEST
HIGH-
VOLTAGE
DC SOURCE
36.8%
TIME
CURRENT WAVEFORM
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
Ir
tRL tDL
IP 100%
90%
10%
0
0
AMPERES
43Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Chip Information
PROCESS: BiCMOS
Typical Operating Circuit
Note: All devices are specified over the -40°C to +85°C oper-
ating temperature range.
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
**Contact factory for availability.
Ordering Information
VBUS_
D+
D-
BAT_A/
BAT_B
CHARGE AND
SYSTEM LOAD
SWITCH
SYS_
SYSTEM
LOAD
SYSTEM
LOAD
1-CELL
Li+
MAX8895V
MAX8895W
MAX8895X
MAX8895Y
BUS_
CONTROL
LOGIC
USB
INTERFACE
OSCILLATOR
PART USB INTERFACE
TYPE PIN-PACKAGE
MAX8895VEWA+T Low speed 25 WLP
2.36mm x 2.36mm
MAX8895WEWA+T** Low speed 25 WLP
2.36mm x 2.36mm
MAX8895XEWA+T Low speed 25 WLP
2.36mm x 2.36mm
MAX8895YEWA+T Full speed 25 WLP
2.36mm x 2.36mm
44 Maxim Integrated
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Package Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a
“+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the
drawing pertains to the package regardless of RoHS status.
PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.
25 WLP W252D2+1 21-0453 Refer to Applications Note 1891
E
D
AAAA
PIN 1
INDICATOR
MARKING
A3
A2
A1
A
See Note 7
0.05
S
S
e
b
E1
D1
SE
SD
0.05
M S
AB
B
A
SIDE VIEW
A
TOP VIEW
BOTTOM VIEW
A
1
PACKAGE OUTLINE
25 BUMPS, WLP PKG. 0.4mm PITCH
21-0453
D
0.64
0.19
0.45
0.025
0.27
1.60
1.60
0.40
0.00
0.00
W252D2+1
2.41 2.44 2.41 2.44
2.25
2.32
2.02
2.36
2.44
2.16
2.25
2.22
2.02
2.36
2.34
2.16
W252F2+1
E
C
D
B
153 42
W252G2+1
W252H2+1
TITLE
DOCUMENT CONTROL NO.
REV.
1
1
APPROVAL
COMMON DIMENSIONS
A
A2
A1
A3
b
E1
D1
e
SD
SE
0.05
0.03
0.03
BASIC
REF
BASIC
MIN
MAX MAX
MIN
E
D
PKG. CODE
DEPOPULATED
BUMPS
NONE
NOTES:
1. Terminal pitch is defined by terminal center to center value.
2. Outer dimension is defined by center lines between scribe lines.
3. All dimensions in millimeter.
4. Marking shown is for package orientation reference only.
5. Tolerance is ± 0.02 unless specified otherwise.
6. All dimensions apply to PbFree (+) package codes only.
7. Front - side finish can be either Black or Clear.
BASIC
BASIC
- DRAWING NOT TO SCALE -
NONE
NONE
NONE
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.
Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical
Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000 45
© 2012 Maxim Integrated The Maxim logo and Maxim Integrated are trademarks of Maxim Integrated Products, Inc.
Li-Ion Chargers with Smart Power Selector,
Adapter Type Detection, and USB Enumeration
MAX8895V/MAX8895W/MAX8895X/MAX8895Y
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 7/10 Initial release —
1 10/10 Added MAX8895W to data sheet 1–38
2 2/11 Added patent information 1
3 4/11 Added contact factory note for MAX8895W 1
4 9/12 Added MAX8895V to data sheet 1–42
