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_______________General Description
The MAX846A is a cost-saving multichemistry battery-
charger system that comes in a space-saving 16-pin
QSOP. This integrated system allows different battery
chemistries (Li-Ion, NiMH or NiCd cells) to be charged
using one circuit.
In its simplest application, the MAX846A is a stand-
alone, current-limited float voltage source that charges
Li-Ion cells. It can also be paired up with a low-cost
microcontroller (µC) to build a universal charger capa-
ble of charging Li-Ion, NiMH, and NiCd cells.
An internal 0.5%-accurate reference allows safe charg-
ing of Li-Ion cells that require tight voltage accuracy.
The voltage- and current-regulation loops used to con-
trol a low-cost external PNP transistor (or P-channel
MOSFET) are independent of each other, allowing more
flexibility in the charging algorithms.
The MAX846A has a built-in 1%, 3.3V, 20mA linear regu-
lator capable of powering the µC and providing a refer-
ence for the µC’s analog-to-digital converters. An
on-board reset notifies the controller upon any unex-
pected loss of power. The µC can be inexpensive, since
its only functions are to monitor the voltage and current
and to change the charging algorithms.
________________________Applications
Li-Ion Battery Packs
Desktop Cradle Chargers
Li-Ion/NiMH/NiCd Multichemistry Battery
Chargers
Cellular Phones
Notebook Computers
Hand-Held Instruments
____________________________Features
♦Multichemistry Charger System (Li-Ion, NiMH, NiCd)
♦Independent Voltage and Current Loops
♦±0.5% Internal Reference for Li-Ion Cells
♦Lowers Cost:
—Stands Alone or Uses Low-Cost µC
—Built-In 1% Linear Regulator Powers µC
—Linear Regulator Provides Reference to µC ADCs
—Built-In µC Reset
—Controls Low-Cost External PNP Transistor or
P-Channel MOSFET
♦Space-Saving 16-Pin QSOP
♦Charging-Current-Monitor Output
♦<1µA Battery Drain when Off
MAX846A
Cost-Saving Multichemistry
Battery-Charger System
________________________________________________________________
Maxim Integrated Products
1
__________________Pin Configuration
MAX846A
Li-ION
BATTERY
ISET
CELL2
GND
PGND
DCIN
CS+
CS- DRV
3.5V
TO
20V
CCV
CCI
PWROK
ON
VL
BATT
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
DRV
PGND
CS-
CS+
BATT
ON
CELL2
PWROK
DCIN
VL
CCI
GND
CCV
VSET
ISET
OFFV
TOP VIEW
MAX846A
QSOP
__________Typical Operating Circuit
19-1121; Rev 0; 9/96
PART
MAX846AC/D
MAX846AEEE -40°C to +85°C
0°C to +70°C
TEMP. RANGE PIN-PACKAGE
Dice*
16 QSOP
*Dice are tested at TA= +25°C only. Contact factory for details.
______________Ordering Information
EVALUATION KIT
AVAILABLE
MAX846A
Cost-Saving Multichemistry
Battery-Charger System
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VDCIN = 10V, ON = VL, IVL = IVSET = 0mA, VCS- = VCS+ = 10V, VBATT = 4.5V, VOFFV = VCELL2 = 0V, TA= 0°C to +85°C, unless
otherwise noted. Typical values are at TA= +25°C.)
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.
DCIN, DRV, CS+, CS-, BATT to GND........................-0.3V, +21V
PGND to GND.....................................................................±0.3V
VL to GND......................................................................-0.3V, 7V
IPWROK................................................................................10mA
PWROK, ISET, CCI, CCV, OFFV, VSET,
CELL2, ON to GND............................................-0.3V, VL + 0.3V
CS+ to CS-..........................................................................±0.3V
VL Short to GND.........................................................Continuous
IDRV...................................................................................100mA
Continuous Power Dissipation (TA= +70°C)
QSOP (derate 8.3mW/°C above +70°C)........................667mW
Operating Temperature Range
MAX846AEEE ....................................................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +160°C
Lead Temperature (soldering, 10sec).............................+300°C
Measured at VSET, IVSET = 0mA, VON = 0V
Rising VL edge, 2% hysteresis
VL = GND
0mA < IVL < 20mA, 3.7V < VDCIN < 20V
CONDITIONS
V-0.5% 1.650 +0.5%
V2.5 2.9VL Undervoltage-Lockout Level V2.9 3.0 3.1PWROK Trip Level mA50Short-Circuit Current Limit V3.267 3.305 3.333Output Voltage V3.7 20.0Operating Range
UNITSMIN TYP MAXPARAMETER
Output Voltage kΩ-2% 20 +2%Output Resistance
Transconductance VISET = 1.7V, VCS+ - VCS- = 165mV 0.95 1 1.05 mA/V
Output Offset Current VCS+ = 4V 3 µA
Input Common-Mode Range Measured at VCS-, VCS+ - VCS- = 165mV 2.1 20.0 V
Maximum Differential Input Voltage VCS- = VISET = 2.1V,
CSA transconductance >0.9mA/V 225 mV
CS- Lockout Voltage When VCS- is less than this voltage, DRV is
disabled. 1.9 2.1 V
CS+, CS- Input Current VCS+ = 20V, VCS+ -VCS- = 165mV 250 µA
CS+, CS- Off Input Current DCIN = VL = ON = GND 0.01 10 µA
VDCIN = 20V, IDRV = IVL = 0mA mA5DCIN Supply Current
VL REGULATOR
REFERENCE
CURRENT-SENSE AMPLIFIER
MAX846A
MAX846A
Cost-Saving Multichemistry
Battery-Charger System
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VDCIN = 10V, ON = VL, IVL = IVSET = 0mA, VCS- = VCS+ = 10V, VBATT = 4.5V, VOFFV = VCELL2 = 0V, TA= 0°C to +85°C, unless
otherwise noted. Typical values are at TA= +25°C.)
VBATT = 10V, ON = GND, CELL2 = GND or VL µA
0.01 1BATT Off Input Current
Current-Loop Set Point IDRV = 5mA, VDRV = 10V
VBATT = 10V, CELL2 = GND or VL
1mA < IDRV < 5mA
1.634 1.650 1.666 V
VVSET = 1.650V, VCELL2 = VL, I DRV = 1mA,
VDRV = 10V
CA Voltage Gain 5
CONDITIONS
V/V
CCI Output Impedance 50 kΩ
Overcurrent Trip Level When VISET exceeds this voltage, DRV current
is disabled. 1.90 2.1 V
DRV Sink Current VDRV = 3V 20 mA
DRV Off Current VDRV = 20V, VON = 0V 0.1 100 µA
225 µA
BATT Input Current %
0.05Voltage-Loop Load Regulation kΩ150CCV Output Impedance V1.25 2.0VSET Common-Mode Input Range
Voltage-Loop Set Point -0.25% 8.4 +0.25%
-0.25% 4.2 +0.25% V
UNITSMIN TYP MAXPARAMETER
Input High Level CELL2, ON, OFFV 2.4 VL V
Input Low Level CELL2, ON, OFFV 0 0.8 V
Input Current CELL2, ON, OFFV 0.01 1 µA
PWROK Output Low Level IPWROK = 1mA, VDCIN = VVL = 2.5V 0.4 V
PWROK Output High Leakage VPWROK = 3.3V 0.01 1 µA
VOLTAGE LOOP
CURRENT LOOP
LOGIC INPUTS AND OUTPUTS
DRIVER
VVSET = 1.650V, VCELL2 = 0V, I DRV = 1mA,
VDRV = 10V
MAX846A
MAX846A
Cost-Saving Multichemistry
Battery-Charger System
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (Note 1)
(VDCIN = 10V, ON = VL, IVL = IVSET = 0mA, VCS- = VCS+ = 10V, VBATT = 4.5V, VOFFV = VCELL2 = 0V, TA= -40°C to +85°C, unless
otherwise noted.)
kΩ
-2% 20 +2%Output Resistance
Transconductance VISET = 1.7V, VCS+ - VCS- = 165mV
Measured at VSET, IVSET = 0mA, VON = 0V
0.93 1.07 mA/V
Rising VL edge, 2% hysteresis
Output Offset Current VCS+ = 4V
0mA < IVL < 20mA, 3.7V < VDCIN < 20V
5
CONDITIONS
µA
CS+, CS- Off Input Current VON = 0V, VCS+ = VCS- = 10V 10 µA
VVSET = 1.650V, VCELL2 = 0V, I DRV = 1mA,
VDRV = 10V -0.35% 4.2 +0.35%
BATT Off Input Current VBATT = 10V, ON = GND, CELL2 = GND or VL 1 µA
V-0.7% 1.650 +0.7%Output Voltage
V2.9 3.1PWROK Trip Level V3.259 3.341Output Voltage
UNITSMIN TYP MAXPARAMETER
Voltage-Loop Set Point VVSET = 1.650V, VCELL2 = VL, I DRV = 1mA,
VDRV = 10V -0.35% 8.4 +0.35% V
Current-Loop Set Point IDRV = 5mA, VDRV = 10V 1.625 1.675 V
Overcurrent Trip Level When VISET exceeds this voltage, DRV current
is disabled. 1.86 2.14 V
DRV Off Current
DRV Sink Current VDRV = 3V 20 mA
VDRV = 20V, ON = GND 100 µA
Note 1: Specifications to -40°C are guaranteed by design and not production tested.
VDCIN = 20V, IDRV = IVL = 0mA mA5DCIN Supply Current
V2.5 3.0VL Undervoltage-Lockout Level
VL REGULATOR
REFERENCE
CURRENT-SENSE AMPLIFIER
VOLTAGE LOOP
CURRENT LOOP
DRIVER
MAX846A
Cost-Saving Multichemistry
Battery-Charger System
_______________________________________________________________________________________
5
1.035
1.020
1.025
1.030
0.990 0 0.4 1.2 2.0
CURRENT-SENSE AMPLIFIER
TRANSCONDUCTANCE vs. ISET VOLTAGE
1.000
0.995
1.015
MAX846-01
ISET VOLTAGE (V)
CSA GM (mA/V)
0.8 1.60.2 1.0 1.80.6 1.4
1.010
1.005
∆V = 165mV
∆V = 200mV
∆V = 250mV
∆V = 100mV
∆V = VCS+ - VCS- 80
50
60
70
002 6 10
BATTERY INPUT CURRENT
vs. BATTERY VOLTAGE
10
40
MAX846-02
BATT VOLTAGE (V)
BATT INPUT CURRENT (µA)
4815 937
30
20
CELL2 = VL
CELL2 = GND
ON
82kΩ
OFF
128kΩ
80
70
60
50
40
30
20
10
0
-10
-20
180
150
120
90
60
30
0
-30
-60
-90
-120
10 10k 100k1k100 1M
CURRENT-LOOP GAIN MAX846-03
FREQUENCY (Hz)
GAIN (dB)
PHASE (DEGREES)
CCCI = 10nF
GAIN
PHASE
40
30
20
10
0
-10
-20
-30
-40
-50
-60
180
150
120
90
60
30
0
-30
-60
-90
--120
10 10k 100k1k100 1M
VOLTAGE-LOOP GAIN MAX846-04
FREQUENCY (Hz)
GAIN (dB)
PHASE (DEGREES)
= - Charging at 100mA
= -Charging at 200mA
2 Li-Ion Cells
CCCV = 10nF
COUT = 4.7µF
TIP2955 PNP PASS TRANSISTOR
GAIN
PHASE
900
800
700
600
500
400
300
200
100
0
9.0
8.8
8.6
8.4
8.2
8.0
7.8
7.6
7.4
7.2
7.0
0 180 24012060
Li-ION CHARGING PROFILE MAX846-04
TIME (MINUTES)
CHARGING CURRENT (mA)
BATTERY VOLTAGE (V)
CHARGING CURRENT
BATTERY VOLTAGE
__________________________________________Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
MAX846A
Cost-Saving Multichemistry
Battery-Charger System
6 _______________________________________________________________________________________
______________________________________________________________Pin Description
PIN FUNCTION
6Float-Voltage Reference-Adjust Input. Leave VSET open for a 4.2V default. See the
Applications
Information
section for adjustment information.
NAME
4 Ground
3Current-Regulation-Loop Compensation Pin. Connect a compensation capacitor (typically 10nF) from
CCI to VL.
23.3V, 20mA, 1% Linear-Regulator Output. VL powers the system µC and other components. Bypass to
GND with a 4.7µF tantalum or ceramic capacitor.
1 Supply Input from External DC Source. 3.7V ≤VDCIN ≤20V.
5Voltage-Regulation-Loop Compensation Pin. Connect a compensation capacitor (typically 10nF) from
CCV to VL.
VSET
CCV
GND
CCI
VL
DCIN
7 ISET
Current-Set Input/Current-Monitor Output. ISET sets the current-regulation point. Connect a resistor
from ISET to GND to monitor the charging current. ISET voltage is regulated at 1.65V by the current-
regulation loop. To adjust the current-regulation point, either modify the resistance from ISET to ground
or connect a fixed resistor and adjust the voltage on the other side of the resistor (Figure 5). The
transconductance of the current-sense amplifier is 1mA/V.
8 OFFV Logic Input that disables the voltage-regulation loop. Set OFFV high for NiCd or NiMH batteries.
9 PWROK Open-Drain, Power-Good Output to µC. PWROK is low when VL is less than 3V. The reset timeout peri-
od can be set externally using an RC circuit (Figure 3).
10 CELL2 Digital Input. CELL2 programs the number of Li-Ion cells to be charged. A high level equals two cells; a
low level equals one cell.
11 ON Charger ON/OFF Input. When low, the driver section is turned off and IBATT <1µA. The VL regulator is
always active.
12 BATT Battery Input. Connect BATT to positive battery terminal.
13 CS+ Current-Sense Amplifier High-Side Input. Connect CS+ to the sense resistor’s power-source side. The
sense resistor may be placed on either side of the pass transistor.
14 CS- Current-Sense Amplifier Low-Side Input. Connect CS- to the sense resistor’s battery side.
15 PGND Power Ground
16 DRV External Pass Transistor (P-channel MOSFET or PNP) Base/Gate Drive Output. DRV sinks current only.
_______________Detailed Description
The MAX846A battery-charging controller combines
three functional blocks: a 3.3V precision, low-dropout
linear regulator (LDO), a precision voltage reference,
and a voltage/current regulator (Figure 1).
Linear Regulator
The LDO regulator output voltage (VL) is two times the
internal reference voltage; therefore, the reference and
LDO track. VL delivers up to 20mA to an external load
and is short-circuit protected. The power-good output
(PWROK) provides microcontroller (µC) reset and
charge-current inhibition.
Voltage Reference
The precision internal reference provides a voltage to
accurately set the float voltage for lithium-ion (Li-Ion)
battery charging. The reference output connects in
series with an internal, 2%-accurate, 20kΩresistor. This
allows the float voltage to be adjusted using one exter-
nal 1% resistor (RVSET) to form a voltage divider
(Figure 4). The float-voltage accuracy is important for
battery life and to ensure full capacity in Li-Ion batter-
ies. Table 1 shows the accuracies attainable using the
MAX846A.
MAX846A
Cost-Saving Multichemistry
Battery-Charger System
_______________________________________________________________________________________ 7
Voltage/Current Regulator
The voltage/current regulator consists of a precision
attenuator, voltage loop, current-sense amplifier, and
current loop. The attenuator can be pin programmed to
set the regulation voltage for one or two Li-Ion cells
(4.2V and 8.4V, respectively). The current-sense ampli-
fier is configured to sense the battery current on the
high side. It is, in essence, a transconductance amplifi-
er converting the voltage across an external sense
resistor (RCS) to a current, and applying this current to
an external load resistor (RISET). Set the charge current
by selecting RCS and RISET. The charge current can
also be adjusted by varying the voltage at the low side
of RISET or by summing/subtracting current from the
ISET node (Figure 5). The voltage and current loops are
individually compensated using external capacitors at
CCV and CCI, respectively. The outputs of these two
loops are OR’ed together and drive an open-drain,
internal N-channel MOSFET transistor sinking current to
ground. An external P-channel MOSFET or PNP transis-
tor pass element completes the loop.
Stability
The
Typical Operating Characteristics
show the loop
gains for the current loop and voltage loop. The domi-
nant pole for each loop is set by the compensation
capacitor connected to each capacitive compensation
pin (CCI, CCV). The DC loop gains are about 50dB for
the current loop and about 33dB for the voltage loop,
for a battery impedance of 250mΩ.
The CCI output impedance (50kΩ) and the CCI capaci-
tor determine the current-loop dominant pole. In Figure
2, the recommended CCCV is 10nF, which places a
dominant pole at 300Hz. There is a high-frequency
pole, due to the external PNP, at approximately fT/ß.
This pole frequency (on the order of a few hundred kilo-
hertz) will vary with the type of PNP used. Connect a
10nF capacitor between the base and emitter of the
PNP to prevent self-oscillation (due to the high-imped-
ance base drive).
Similarly, the CCV output impedance (150kΩ) and the
CCV capacitor set the voltage-loop dominant pole. In
Figure 2, the compensation capacitance is 10nF, which
places a dominant pole at 200Hz.
The battery impedance directly affects the voltage-loop
DC and high-frequency gain. At DC, the loop gain is
proportional to the battery resistance. At higher fre-
quencies, the AC impedance of the battery and its con-
nections introduces an additional high-frequency zero.
A 4.7µF output capacitor in parallel with the battery,
mounted close to BATT, minimizes the impact of this
impedance. The effect of the battery impedance on DC
gain is noticeable in the Voltage-Loop-Gain graph (see
Typical Operating Characteristics
). The solid line repre-
sents voltage-loop gain versus frequency for a fully
charged battery, when the battery energy level is high
and the ESR is low. The charging current is 100mA. The
dashed line shows the loop gain with a 200mA charg-
ing current, a lower amount of stored energy in the bat-
tery, and a higher battery ESR.
__________Applications Information
Stand-Alone Li-Ion Charger
Figure 2 shows the stand-alone configuration of the
MAX846A. Select the external components and pin
configurations as follows:
• Program the number of cells: Connect CELL2 to GND
for one-cell operation, or to VL for two-cell operation.
• Program the float voltage: Connect a 1% resistor from
VSET to GND to adjust the float voltage down, or to
VL to adjust it up. If VSET is unconnected, the float
voltage will be 4.2V per cell. Let the desired float volt-
age per cell be VF, and calculate the resistor value
as follows:
Table 1. Float-Voltage Accuracy
±0.9%TOTAL
±0.25%VSET amplifier and divider accuracy
±0.15%
VSET error due to external divider. Calculated from a 2% internal 20kΩresistor tolerance and
a 1% external RVSET resistor tolerance. The total error is 3% x (adjustment). Assume max
adjustment range of 5%.
±0.5%Internal-reference accuracy
ERROR SOURCE ERROR
MAX846A
Cost-Saving Multichemistry
Battery-Charger System
8 _______________________________________________________________________________________
MAX846A
VL 5nF
VL
VL
10k
5nF
4.7µF
RDRV
660Ω
0.01µF
RCS
165mΩ
IBATT
TO µC
CA
VA
1.65V
CL
CSA
CS+
CS-
1k
BST
DCIN DRV
DC INPUT (OR P-CHANNEL)
3.5V TO 20V
3.3V, 1%
LDO
1.65V, 0.5%
REF
400k, 1%
(±5% ADJ)
Li
OR
Ni
N
N
N
BATT
REFOK
CS- > 2V
VL > 3V
ON
ON
OFF
VL
2V
20k, 2%
3.3V
TO
µC
GND
OR
DAC
TO
ADC
4.7µF
PWROK
DRV ENABLE
VL
2 Li
1 Li
OFF OFFV
VSET
GND
CELL2
CCV
CCI
ISET
PGND
OPEN
OR
DAC
ON
BST
VA
RVSET
Figure 1. Functional Diagram
MAX846A
Cost-Saving Multichemistry
Battery-Charger System
_______________________________________________________________________________________ 9
where VX is either GND or VL, and VFis the per-cell
float voltage. In the circuit of Figure 1, RVSET is
400kΩ. RVSET and the internal 20kΩresistor form a
divider, resulting in an adjustment range of approxi-
mately ±5%.
The current-regulation loop attempts to maintain the
voltage on ISET at 1.65V. Selecting resistor RISET deter-
mines the reflected voltage required at the current-
sense amplifier input.
• Calculate RCS and RISET as follows:
RCS = VCS / IBATT
RISET (in kΩ) = 1.65V / VCS
where the recommended value for VCS is 165mV.
• Connect ON to PWROK to prevent the charge current
from turning on until the voltages have settled.
Minimize power dissipation in the external pass transis-
tor. Power dissipation can be controlled by setting the
DCIN input supply as low as possible, or by making
VDCIN track the battery voltage.
Microprocessor-Controlled
Multichemistry Operation
The MAX846A is highly adjustable, allowing for simple
interfacing with a low-cost µC to charge Ni-based and
Li-Ion batteries using one application circuit (Figure 3).
R = 20k
4.2
1.65 V V
V 4.2
VSET XF
F
Ω−
−
MAX846A
IBATT
CCI
GND
CCV
EXTERNAL PASS TRANSISTOR
CAN BE EITHER PNP OR PMOS FET.
OFFV
PGND
DRV BATTCS-
( )
10nF
0.165V
CS+
DCIN
3.7V TO 20V
ISET
CELL2
PWROK
ON
VL
DCIN VSET
100k
RVSET
VL
ADJUST
(UP)
(DOWN)
10k
RISET
VL
(2 CELLS)
(1 CELL)
0.01µF
4.7µF
0.01µF
RDRV
660Ω
RCS 4.7µF
Figure 2. Stand-Alone Li-Ion Charger
MAX846A
Cost-Saving Multichemistry
Battery-Charger System
10 ______________________________________________________________________________________
Component selection is similar to that of stand-alone
operation. By using DACs or µC PWM outputs, the float
voltage and charging current can be adjusted by the
µC. When a Ni-based battery is being charged, disable
the float-voltage regulation using the OFFV input. The
µC can also monitor the charge current through the
battery by reading the ISET output’s voltage using its
ADC. Similarly, the battery voltage can be measured
using a voltage divider from the battery.
Note that the µC only needs to configure the system for
correct voltage and current levels for the battery being
charged, and for Ni-based batteries to detect end-of-
charge and adjust the current level to trickle. The con-
troller is not burdened with the regulation task.
Float-voltage accuracy is important for battery life and
for reaching full capacity for Li-Ion batteries. Table 1
shows the accuracy attainable using the MAX846A.
For best float-voltage accuracy, set the DRV current to
1mA (RDRV = 660Ωfor a PNP pass transistor).
High-Power Multichemistry
Offline Charger
The circuit in Figure 6 minimizes power dissipation in
the pass transistor by providing optical feedback to the
input power source. The offline AC/DC converter main-
tains 1.2V across the PNP. This allows much higher
charging currents than can be used with conventional
power sources.
P
VDD
ADC (MEASURE IBATT)
PWM/DAC (CONTROL CHARGE I)
PWM/DAC (CONTROL FLOAT V)
I/O (HIGH = DISABLE FLOAT V)
I/O (HIGH = 2 Li CELLS)
I/O (LOW = TURN OFF CHARGE)
ADC (MEASURE V(BATT))
MAX846A
CCI
GND
RST
CCV
OFFV
PGND
DRV BATT
CS-CS+
DCIN
3.7V TO 20V
ISET
VL
CELL2
PWROK
ON
DCIN
VSET
Li OR Ni
MICROCONTROLLER
Figure 3. Desktop Multichemistry Charger Concept
MAX846A
Cost-Saving Multichemistry
Battery-Charger System
______________________________________________________________________________________ 11
Figure 4. VSET Adjustment Methods
Figure 5. ISET Adjustment Methods
Figure 6. Low-Cost Desktop Multichemistry Charger Concept
MAX846A
DAC
0 TO VL
20k VSET 400k
n
WITH VOLTAGE OUTPUT DAC
0 100%
2%
1.65V 1%
MAX846A
20k VSET 400k
2%
1.65V 1%
µC
PWM
OUTPUT
WITH PWM FROM MICROCONTROLLER
MAX846A
DAC
20k
ISET
20k n
WITH VOLTAGE OUTPUT DAC
MAX846A
10k10k
0 100%
ISET µC
PWM
OUTPUT
20k
WITH PWM FROM MICROCONTROLLER
FEEDBACK
OPTO-COUPLER
AC/DC
CONVERTER
MAX846
MICRO
CONTROLLER
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.
12
__________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600
© 1996 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
MAX846A
Cost-Saving Multichemistry
Battery-Charger System
___________________Chip Topography
ON
CS+
BATT
DCINVL DRV PGND
CELL2PWROKOFFVISET
CS-
VSET
CCV
GND
CCI
0.105"
(2.67mm)
0.085"
(2.165mm)
SUBSTRATE CONNECTED TO GND
TRANSISTOR COUNT: 349
