General Description
The MAX6887/MAX6888 multivoltage supply supervi-
sors provide several voltage-detector inputs, one watch-
dog input, and three outputs. Each voltage-detector
input offers a factory-set undervoltage and overvoltage
threshold. Manual reset and margin disable inputs offer
additional flexibility.
The MAX6887 offers six voltage-detector inputs, while
the MAX6888 offers four inputs. Output RESET asserts
when any input voltage drops below its respective
undervoltage threshold or manual reset MR is asserted.
Output OV asserts when any input voltage exceeds its
respective overvoltage threshold. Monitor standard
supply voltages listed in the
Selector Guide
.
The MAX6887/MAX6888 offer a watchdog timer with an
initial and normal timeout periods of 102.4s and 1.6s,
respectively. Watchdog output WDO asserts when the
watchdog timer expires. Connect WDO to manual reset
input MR to generate resets when the watchdog timer
expires. RESET, OV, and WDO are active-low, open-
drain outputs.
The MAX6887/MAX6888 are available in a 5mm x 5mm
x 0.8mm, 16-pin thin QFN package and operate over
the extended -40°C to +85°C temperature range.
Applications
Multivoltage Systems
Telecom
Networking
Servers/Workstations/Storage Systems
Features
oHex/Quad Voltage Detectors
oUndervoltage and Overvoltage Thresholds
o1% Threshold Accuracy
oMargining Disable and Manual Reset Input
oWatchdog Timer
oOpen-Drain RESET, OV, and WDO Outputs
o180ms (min) Reset Timeout Period
oFew External Components
oSmall 5mm x 5mm, 16-Pin Thin QFN Packages
MAX6887/MAX6888
Hex/Quad, Power-Supply Supervisory Circuits
________________________________________________________________
Maxim Integrated Products
1
PART TEMP RANGE PIN-PACKAGE
MAX6887_ETE+ -40°C to +85°C 16 Thin QFN-EP*
MAX6888_ETE+ -40°C to +85°C 16 Thin QFN-EP*
Ordering Information
Selector Guide
19-0291; Rev 2; 2/10
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Pin Configurations and Typical Operating Circuit appear at
end of data sheet.
Note: Insert the desired letter from the Selector Guide into the
blank to complete the part number.
+Denotes a lead(Pb)-free/RoHS-compliant package.
*
EP = Exposed pad.
NOMINAL INPUT VOLTAGE (V)*
PART IN1 IN2 IN3 IN4 IN5 IN6
TOL
(%)
MAX6887AETE 5.0 3.3 2.5 1.8 Adj Adj 5
MAX6887BETE 5.0 3.3 2.5 Adj Adj Adj 5
MAX6887CETE 5.0 3.3 1.8 Adj Adj Adj 5
MAX6887DETE 3.3 2.5 1.8 1.5 Adj Adj 5
MAX6887EETE 3.3 2.5 1.8 Adj Adj Adj 5
MAX6887FETE 3.3 2.5 1.5 Adj Adj Adj 5
MAX6887GETE 3.3 2.5 Adj Adj Adj Adj 5
MAX6887HETE 3.3 1.8 Adj Adj Adj Adj 5
MAX6887QETE Adj Adj Adj Adj Adj Adj 5
NOMINAL INPUT VOLTAGE (V)*
PART IN1 IN2 IN3 IN4 IN5 IN6
TOL
(%)
MAX6887IETE 5.0 3.3 2.5 1.8 Adj Adj 10
MAX6887JETE 5.0 3.3 2.5 Adj Adj Adj 10
MAX6887KETE 5.0 3.3 1.8 Adj Adj Adj 10
MAX6887LETE 3.3 2.5 1.8 1.5 Adj Adj 10
MAX6887METE 3.3 2.5 1.8 Adj Adj Adj 10
MAX6887NETE 3.3 2.5 1.5 Adj Adj Adj 10
MAX6887OETE 3.3 2.5 Adj Adj Adj Adj 10
MAX6887PETE 3.3 1.8 Adj Adj Adj Adj 10
MAX6887RETE Adj Adj Adj Adj Adj Adj 10
*
See thresholds options tables (Tables 1 and 2) for actual undervoltage and overvoltage thresholds.
Selector Guides continued at end of data sheet.
MAX6887/MAX6888
Hex/Quad, Power-Supply Supervisory Circuits
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN1–VIN4 or VCC = 2.7V to 5.8V, WDI = GND, MARGIN = MR = BP, TA= -40°C to +85°C, unless otherwise noted. Typical values are
at TA= +25°C.) (Notes 1, 2)
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.
(All voltages referenced to GND.)
IN1–IN6, VCC, RESET, OV, WDO .............................-0.3V to +6V
WDI, MR, MARGIN ...................................................-0.3V to +6V
BP .............................................................................-0.3V to +3V
Input/Output Current (all pins)..........................................±20mA
Continuous Power Dissipation (TA= +70°C)
16-Pin 5mm x 5mm Thin QFN
(derate 20.8mW/°C above +70°C)..............................1667mW
Maximum Junction Temperature .....................................+150°C
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX
UNITS
Operating Voltage Range
(Note 3)
Voltage on either one of IN1–IN4 or VCC to
guarantee the part is fully operational 2.7 5.8 V
Supply Current ICC VIN1 = 5.8V, IN2–IN6 = GND, no load 0.9 1.2 mA
IN1–IN6, IN_ falling, TA = +25°C to +85°C -1 +1
Threshold Accuracy
(See the Selector Guide)VTH IN1–IN6, IN_ falling, TA = -40°C to +85°C
-1.5 +1.5
% VTH
Threshold Hysteresis
VTH-HYST
0.3
% VTH
Threshold Tempco
∆VTH/°C
10
ppm/°C
IN_ Input Impedance RIN
For VIN_ < highest VIN1–IN4 and
VIN_ < VCC (not ADJ), thresholds are not set
as adjustable
130 200 300
kΩ
IN5, IN6 (MAX6887 only)
IN_ Input Leakage Current IIN IN1–IN4 set as adjustable thresholds
-150 +150
nA
Power-Up Delay tD-PO VCC ≥ 2.5V 2.5 ms
IN_ to RESET or OV Delay tD-R IN_ falling/rising, 100mV overdrive 20 µs
RESET Timeout Period tRP
180 200 220
ms
OV Timeout Period tOP 25 µs
RESET, OV, and WDO Output
Low VOL ISINK = 4mA, output asserted 0.4 V
RESET, OV, and WDO Output
Open-Drain Leakage Current ILKG Output high impedance -1 +1 µA
MAX6887/MAX6888
Hex/Quad, Power-Supply Supervisory Circuits
_______________________________________________________________________________________ 3
Note 1: 100% production tested at TA= +25°C and TA= +85°C. Specifications at TA= -40°C are guaranteed by design.
Note 2: Device may be supplied from any one of IN1–IN4 or VCC.
Note 3: The internal supply voltage, measured at VCC, equals the maximum of IN1–IN4.
Note 4: Versions Q and R require that power be applied through VCC.
ELECTRICAL CHARACTERISTICS (continued)
(VIN1–VIN4 or VCC = 2.7V to 5.8V, WDI = GND, MARGIN = MR = BP, TA= -40°C to +85°C, unless otherwise noted. Typical values are
at TA= +25°C.) (Notes 1, 2)
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX
UNITS
VIL 0.6
MR, MARGIN, WDI Input Voltage
VIH 1.4 V
MR Input Pulse Width tMR 1µs
MR Glitch Rejection
100
ns
MR to RESET or OV Delay tD-MR
200
ns
MR to Internal BP Pullup Current IMR VMR = 1.4V 5 10 15 µA
MARGIN to Internal BP Pullup
Current
IMARGIN
VMARGIN = 1.4V 5 10 15 µA
WDI Pulldown Current IWDI VWDI = 0.6V 5 10 15 µA
WDI Input Pulse Width 50 ns
tWDI Initial
92.16 102.4 112.64
Watchdog Timeout Period tWD Normal
1.44
1.6
1.76
s
Typical Operating Characteristics
(VIN1–VIN4 or VCC = 5V, WDI = GND, MARGIN = MR = BP, TA= +25°C, unless otherwise noted.)
IN1–IN4 SUPPLY CURRENT
vs. IN1–IN4 SUPPLY VOLTAGE
MAX6887 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
5.64.63.6
0.75
0.80
0.85
0.90
0.95
1.00
0.70
2.6
TA = +85°C
TA = +25°C
TA = -40°C
VCC SUPPLY CURRENT
vs. VCC SUPPLY VOLTAGE
MAX6887 toc02
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
5.64.63.6
0.75
0.80
0.85
0.90
0.95
1.00
0.70
2.6
TA = +85°C
TA = +25°C
TA = -40°C
TIMEOUT PERIOD (ms)
185
190
195
200
210
205
215
220
180
RESET TIMEOUT PERIOD
vs. TEMPERATURE
MAX6887 toc03
TEMPERATURE (°C)
603510-15-40 85
PROPAGATION DELAY (µs)
1.25
1.50
1.75
2.00
2.50
2.25
2.75
3.00
1.00
MR TO RESET OUTPUT PROPAGATION
DELAY vs. TEMPERATURE
MAX6887 toc09
TEMPERATURE (°C)
603510-15-40 85
MAX6887/MAX6888
Hex/Quad, Power-Supply Supervisory Circuits
4 _______________________________________________________________________________________
PROPAGATION DELAY (µs)
21
22
23
24
25
26
27
28
29
30
20
IN_ TO RESET OR OV
PROPAGATION DELAY vs. TEMPERATURE
MAX6887 toc04
TEMPERATURE (°C)
603510-15-40 85
100mV OVERDRIVE
TIMEOUT PERIOD (s)
1.525
1.550
1.575
1.600
1.650
1.625
1.675
1.700
1.500
WATCHDOG TIMEOUT PERIOD
vs. TEMPERATURE
MAX6887 toc05
TEMPERATURE (°C)
603510-15-40 85
NORMALIZED IN_ THRESHOLD
0.998
0.997
0.996
0.999
1.000
1.001
1.003
1.002
1.004
1.005
0.995
NORMALIZED IN_ THRESHOLD
vs. TEMPERATURE
MAX6887 toc06
TEMPERATURE (°C)
603510-15-40 85
100101 1000
MAXIMUM IN_ TRANSIENT
vs. IN_THRESHOLD OVERDRIVE
MAX6887 toc07
IN_ THRESHOLD OVERDRIVE (mV)
MAXIMUM TRANSIENT DURATION (µs)
25
50
75
100
125
150
175
200
0
PO_ ASSERTION OCCURS
ABOVE THIS LINE
OUTPUT-VOLTAGE LOW vs. SINK CURRENT
MAX8667 toc08
SINK CURRENT (mA)
OUTPUT-VOLTAGE LOW (mV)
8624
50
100
150
200
300
250
350
400
0
0101214
Pin Description
PIN
MAX6887
MAX6888
NAME
FUNCTION
11
RESET
Open-Drain, Active-Low Reset Output. RESET asserts when any input voltage falls below its
undervoltage threshold or when MR is pulled low. RESET remains low for 200ms after all
assertion-causing conditions are cleared. An external pullup resister is required.
22WDO
Open-Drain, Active-Low Watchdog Timer Output. Logic output for the watchdog timer function.
WDO goes low when WDI is not strobed high-to-low or low-to-high within the watchdog timeout
period.
33OV
Open-Drain Active-Low Overvoltage Output. OV asserts when any input voltage exceeds its
overvoltage threshold. OV remains low for 25µs after all overvoltage conditions are cleared.
An external pullup resistor is required.
4 4 GND Ground
Typical Operating Characteristics (continued)
(VIN1–VIN4 or VCC = 5V, WDI = GND, MARGIN = MR = BP, TA= +25°C, unless otherwise noted.)
MAX6887/MAX6888
Hex/Quad, Power-Supply Supervisory Circuits
_______________________________________________________________________________________ 5
Pin Description (continued)
PIN
MAX6888
NAME
FUNCTION
55MR
Manual Reset Input. Pull MR low to assert RESET. Connect MR to WDO to generate resets
when the watchdog timer expires. Leave MR unconnected or connect to DBP if unused. MR is
internally pulled up to BP through a 10µA current source.
66
MARGIN
Margin Input. When MARGIN is pulled low, RESET is held in its existing state independent of
subsequent changes in monitored input voltages or the watchdog timer expiration. MARGIN is
internally pulled up to BP through a 10µA current source. Leave MARGIN unconnected or
connect to BP if unused. MARGIN overrides MR if both are asserted at the same time.
7 7 WDI
Watchdog Timer Input. Logic input for the watchdog timer function. If WDI is not strobed with a
valid low-to-high or high-to-low transition within the selected watchdog timeout period, WDO
asserts. WDI is internally pulled down to GND through a 10µA current sink.
8 8 I.C. Internal Connection. Leave unconnected.
99V
CC
Internal Power-Supply Voltage. Bypass VCC to GND with a 1µF ceramic capacitor as close to
the device as possible. VCC supplies power to the internal circuitry. VCC is internally powered
from the highest of the monitored IN1–IN4 voltages. Do not use VCC to supply power to external
circuitry. To externally supply VCC, see the Powering the MAX6887/MAX6888 section.
10 10 BP
Bypass Voltage. The internally generated voltage at BP supplies power to internal logic and
output RESET. Connect a 1µF capacitor from BP to GND as close to the device as possible. Do
not use BP to supply power to external circuitry.
11 — IN6
Input Voltage Detector 6. IN6 monitors both undervoltage and overvoltage conditions. See the
thresholds options (Tables 1 and 2) for available thresholds. IN6 cannot power the device. For
improved noise immunity, bypass IN6 to GND with a 0.1µF capacitor installed as close to the
device as possible.
12 — IN5
Input Voltage Detector 5. IN5 monitors both undervoltage and overvoltage conditions. See the
thresholds options (Tables 1 and 2) for available thresholds. IN5 cannot power the device. For
improved noise immunity, bypass IN5 to GND with a 0.1µF capacitor installed as close to the
device as possible.
13 13 IN4
Input Voltage Detector 4. IN4 monitors both undervoltage and overvoltage conditions. See the
thresholds options (Tables 1 and 2) for available thresholds. Power the device through IN1–IN4
or VCC (see the Powering the MAX6887/MAX6888 section). For improved noise immunity,
bypass IN4 to GND with a 0.1µF capacitor installed as close to the device as possible.
14 14 IN3
Input Voltage Detector 3. IN3 monitors both undervoltage and overvoltage conditions. See the
thresholds options (Tables 1 and 2) for available thresholds. Power the device through IN1–IN4
or VCC (see the Powering the MAX6887/MAX6888 section). For improved noise immunity,
bypass IN3 to GND with a 0.1µF capacitor installed as close to the device as possible.
15 15 IN2
Input Voltage Detector 2. IN2 monitors both undervoltage and overvoltage conditions. See the
thresholds options (Tables 1 and 2) for available thresholds. Power the device through IN1–IN4
or VCC (see the Powering the MAX6887/MAX6888 section). For improved noise immunity,
bypass IN2 to GND with a 0.1µF capacitor installed as close to the device as possible.
16 16 IN1
Input Voltage Detector 1. IN1 monitors both undervoltage and overvoltage conditions. See the
thresholds options (Tables 1 and 2) for available thresholds. Power the device through IN1–IN4
or VCC (see the Powering the MAX6887/MAX6888 section). For improved noise immunity,
bypass IN1 to GND with a 0.1µF capacitor installed as close to the device as possible.
— 11, 12 N.C.
No Connection. Not internally connected.
——EP
Exposed Paddle. Internally connected to GND. Connect EP to GND or leave unconnected.
MAX6887/MAX6888
Hex/Quad, Power-Supply Supervisory Circuits
6 _______________________________________________________________________________________
Functional Diagram
LOGIC ARRAY
(VIRTUAL DIODES)
WDI
IN2 DETECTOR
IN3 DETECTOR
IN4 DETECTOR
IN5 DETECTOR
IN6 DETECTOR
IN2
IN3
IN4
IN5
(N.C.)
IN6
(N.C.)
IN1 *IN_
DETECTOR
1µF
1µF
GND
( ) MAX6888 ONLY
2.55V
LDO
BP
VCC
MR
MARGIN
MAX6887
MAX6888
*FOR ADJUSTABLE INPUTS REFER TO THE ADJUSTABLE THRESHOLD INPUTS SECTION.
REFERENCE
RESET
WDO
OV
OV TIMING BLOCK
RESET TIMING BLOCK
WDO TIMING BLOCK
MAX6887/MAX6888
Hex/Quad, Power-Supply Supervisory Circuits
_______________________________________________________________________________________ 7
Detailed Description
The MAX6887/MAX6888 provide several supply-detector
inputs, one watchdog input, and three outputs for power-
supply monitoring applications. The MAX6887 offers six
voltage-detector inputs, while the MAX6888 offers four.
Each voltage-detector input offers both an undervoltage
and overvoltage threshold.
The undervoltage and overvoltage thresholds are facto-
ry-set for monitoring standard supply voltages (see the
Selector Guide
). Inputs in the
Selector Guide
that con-
tain “Adj” allow an external voltage-divider to be con-
nected to set a user-defined threshold.
RESET goes low when any input voltage drops below
its undervoltage threshold or when MR is brought low.
RESET stays low for 200ms after all assertion-causing
conditions have been cleared. OV goes low when an
input voltage rises above its overvoltage threshold. OV
typically stays low for 25µs (typ) after all inputs fall
back under their overvoltage thresholds.
The MAX6887/MAX6888 offer a watchdog timer with
initial and normal timeout periods of 102.4s and 1.6s,
respectively. WDO goes low when the watchdog timer
expires and deasserts when WDI transitions from low-
to-high or high-to-low.
Powering the MAX6887/MAX6888
The MAX6887/MAX6888 derive power from the voltage-
detector inputs IN1–IN4 or through an externally sup-
plied VCC. A virtual diode-ORing scheme selects the
positive input that supplies power to the device (see
the
Functional Diagram
). The highest input voltage on
IN1–IN4 supplies power to the device. One of IN1–IN4
must be at least 2.7V to ensure proper operation.
Internal hysteresis ensures that the supply input that
initially powered the device continues to power the
device when multiple input voltages are within 50mV of
each other.
VCC powers the analog circuitry and is the bypass con-
nection for the MAX6887/MAX6888 internal supply.
Bypass VCC to GND with a 1µF ceramic capacitor
installed as close to the device as possible. The inter-
nal supply voltage, measured at VCC, equals the maxi-
mum of IN1–IN4. If VCC is externally supplied, VCC
must be at least 200mV higher than any voltage
applied to IN1–IN4 and VCC must be brought up first.
VCC always powers the device when all IN_ are factory
set as “Adj.” Do not use the internally generated VCC to
provide power to external circuitry.
The MAX6887/MAX6888 generate a supply voltage at
BP for the internal logic circuitry. Bypass BP to GND with
a 1µF ceramic capacitor installed as close to the device
as possible. The nominal BP output voltage is +2.55V.
Do not use BP to provide power to external circuitry.
Inputs
The MAX6887 offers six voltage-detector inputs, while
the MAX6888 offers four voltage-detector inputs. Each
voltage-detector input offers an undervoltage and over-
voltage threshold set at the factory to monitor standard
supply voltages (see the
Selector Guide
). The 5% and
10% tolerances are based on maximum and minimum
threshold values. Actual thresholds for the
MAX6887/MAX6888 are shown in Tables 1 and 2.
Inputs in the
Selector Guide
listing “Adj” allow an exter-
nal voltage-divider to be connected to set a user-
defined threshold.
Adjustable Threshold Inputs
Inputs listed in the
Selector Guide
containing “Adj” for
inputs allow external resistor voltage-dividers to be
connected at the voltage-detector inputs. These inputs
monitor any voltage supply higher than 0.6V (see
Figure 1). Use the following equation to set a voltage-
MAX6887
MAX6888
VIN
IN_
R1
R2
*VREFUV
*VREFOV AND VREFUV ARE REFERENCED
TO 0.6V ACCORDING TO THE DEVICE'S TOLERANCE
*VREFOV
Figure 1. Adjusting the Monitored Threshold
MAX6887/MAX6888
Hex/Quad, Power-Supply Supervisory Circuits
8 _______________________________________________________________________________________
detector input (IN1–IN6) to monitor a user-defined sup-
ply voltage:
where VMON is the desired voltage to be monitored.
Use the following procedure to design the proper volt-
age-divider and calculate thresholds:
1) Pick a value for R2. Use the equation above with
the desired supply voltage to be monitored and
solve for R1. Use high-value resistors R1 and R2 to
minimize current consumption due to low leakage
currents.
2) To find the actual undervoltage and overvoltage
thresholds, use the following equations:
VREFUV and VREFOV are the undervoltage and overvolt-
age thresholds listed in Tables 1 and 2 that allow
adjustable thresholds. Their values are based on toler-
ances of ±7.5% and ±12.5% from a 0.6V reference.
See the
Selector Guide
to find which thresholds in
Tables 1 and 2 are adjustable.
Manual Reset (MR)
Many µP-based products require manual reset capability
to allow an operator or external logic circuitry to initiate a
reset. The manual reset input (MR) can be connected
directly to a switch without an external pullup resistor or
debouncing network. MR is internally pulled up to BP.
Leave unconnected if not used. MR is internally pulled
up to BP through a 10µA current source. MR is designed
to reject fast, falling transients (typically 100ns pulses)
and MR must be held low for a minimum of 1µs to assert
RESET. Connect a 0.1µF capacitor from MR to ground to
provide additional noise immunity. After MR transitions
from low to high, RESET remains asserted for the dura-
tion of its time delay.
Margin Output Disable (MARGIN)
MARGIN allows system-level testing while power sup-
plies exceed the normal operating ranges. Drive
MARGIN low to hold RESET, OV, and WDO in their
VV
V
V
VV
V
V
ACTUALUV MON REFUV
ACTUALOV MON REFOV
=×
⎛
⎝
⎜⎞
⎠
⎟
=×
⎛
⎝
⎜⎞
⎠
⎟
06
06
.
.
06 2
12
.V V R
RR
MON
=×
+
⎛
⎝
⎜⎞
⎠
⎟
Table 1. MAX6887 Threshold Options
UV THRESHOLDS (V) OV THRESHOLDS (V)
PART IN1 IN2 IN3 IN4 IN5 IN6 IN1 IN2 IN3 IN4 IN5 IN6
MAX6887AETE 4.620 3.060 2.310 1.670 0.557 0.557 5.360 3.540 2.680 1.930 0.643 0.643
MAX6887BETE 4.620 3.060 2.310 0.557 0.557 0.557 5.360 3.540 2.680 0.643 0.643 0.643
MAX6887CETE 4.620 3.060 1.670 0.557 0.557 0.557 5.360 3.540 1.930 0.643 0.643 0.643
MAX6887DETE 3.060 2.310 1.670 1.390 0.557 0.557 3.540 2.680 1.930 1.610 0.643 0.643
MAX6887EETE 3.060 2.310 1.670 0.557 0.557 0.557 3.540 2.680 1.930 0.643 0.643 0.643
MAX6887FETE 3.060 2.310 1.390 0.557 0.557 0.557 3.540 2.680 1.610 0.643 0.643 0.643
MAX6887GETE 3.060 2.310 0.557 0.557 0.557 0.557 3.540 2.680 0.643 0.643 0.643 0.643
MAX6887HETE 3.060 1.670 0.557 0.557 0.557 0.557 3.540 1.930 0.643 0.643 0.643 0.643
MAX6887QETE 0.557 0.557 0.557 0.557 0.557 0.557 0.643 0.643 0.643 0.643 0.643 0.643
MAX6887IETE 4.380 2.880 2.190 1.580 0.527 0.527 5.620 3.700 2.810 2.020 0.673 0.673
MAX6887JETE 4.380 2.880 2.190 0.527 0.557 0.557 5.620 3.700 2.810 0.673 0.673 0.673
MAX6887KETE 4.380 2.880 1.580 0.527 0.557 0.557 5.620 3.700 2.020 0.673 0.673 0.673
MAX6887LETE 2.880 2.190 1.580 1.310 0.557 0.557 3.700 2.810 2.020 1.680 0.673 0.673
MAX6887METE 2.880 2.190 1.580 0.527 0.557 0.557 3.700 2.810 2.020 0.673 0.673 0.673
MAX6887NETE 2.880 2.190 1.310 0.527 0.557 0.557 3.700 2.810 1.680 0.673 0.673 0.673
MAX6887OETE 2.880 2.190 0.527 0.527 0.557 0.557 3.700 2.810 0.673 0.673 0.673 0.673
MAX6887PETE 2.880 1.580 0.527 0.527 0.557 0.557 3.700 2.020 0.673 0.673 0.673 0.673
MAX6887RETE 0.527 0.527 0.527 0.527 0.527 0.527 0.673 0.673 0.673 0.673 0.673 0.673
existing state while system-level testing occurs. Leave
MARGIN unconnected or connect to BP if unused. An
internal 10µA current source pulls MARGIN to BP.
MARGIN overrides MR if both are asserted at the
same time. The state of RESET, OV, and WDO does not
change while MARGIN = GND.
RESET
,
OV
, and
WDO
Outputs
The MAX6887/MAX6888 feature three active-low open-
drain outputs: RESET, OV, and WDO. After power-up or
overvoltage/undervoltage conditions, RESET and OV
remain in their active states until their timeout periods
expire and no undervoltage/overvoltage conditions are
present (see Figure 2).
OV asserts when any monitored input is above its over-
voltage threshold and remains asserted until all inputs
are below their thresholds and its respective 25µs time-
out period expires. Connect OV to MR to bring RESET
low during an overvoltage condition. OV requires a
pullup resistor (unless connected to MR).
RESET asserts when any monitored input is below its
undervoltage threshold or MR is asserted. RESET
remains asserted for 200ms after all assertion-causing
conditions have been cleared. Configure RESET to
assert when the watchdog timer expires by connecting
WDO to MR. RESET requires a pullup resistor.
WDO asserts when the watchdog timer expires. See
the
Configuring the Watchdog Timer
section for a com-
plete description. WDO requires a pullup resistor.
Configuring the Watchdog Timer
A watchdog timer monitors microprocessor (µP) soft-
ware execution for a stalled condition and resets the µP
if it stalls. Connect the watchdog timer output WDO to
the reset input or a nonmaskable interrupt of the µP.
The watchdog timer features independent initial and
normal watchdog timeout periods of 102.4s and 1.6s,
respectively.
MAX6887/MAX6888
Hex/Quad, Power-Supply Supervisory Circuits
_______________________________________________________________________________________ 9
Table 2. MAX6888 Threshold Options
UV THRESHOLDS (V) OV THRESHOLDS (V)
PART IN1 IN2 IN3 IN4 IN1 IN2 IN3 IN4
MAX6888AETE 4.620 3.060 2.310 1.670 5.360 3.540 2.680 1.930
MAX6888BETE 4.620 3.060 2.310 0.557 5.360 3.540 2.680 0.643
MAX6888CETE 4.620 3.060 1.670 0.557 5.360 3.540 1.930 0.643
MAX6888DETE 3.060 2.310 1.670 1.390 3.540 2.680 1.930 1.610
MAX6888EETE 3.060 2.310 1.670 0.557 3.540 2.680 1.930 0.643
MAX6888FETE 3.060 2.310 1.390 0.557 3.540 2.680 1.610 0.643
MAX6888GETE 3.060 2.310 0.557 0.557 3.540 2.680 0.643 0.643
MAX6888HETE 3.060 1.670 0.557 0.557 3.540 1.930 0.643 0.643
MAX6888QETE 0.557 0.557 0.557 0.557 0.643 0.643 0.643 0.643
MAX6888IETE 4.380 2.880 2.190 1.580 5.620 3.700 2.810 2.020
MAX6888JETE 4.380 2.880 2.190 0.527 5.620 3.700 2.810 0.673
MAX6888KETE 4.380 2.880 1.580 0.527 5.620 3.700 2.020 0.673
MAX6888LETE 2.880 2.190 1.580 1.310 3.700 2.810 2.020 1.680
MAX6888METE 2.880 2.190 1.580 0.527 3.700 2.810 2.020 0.673
MAX6888NETE 2.880 2.190 1.310 0.527 3.700 2.810 1.680 0.673
MAX6888OETE 2.880 2.190 0.527 0.527 3.700 2.810 0.673 0.673
MAX6888PETE 2.880 1.580 0.527 0.527 3.700 2.020 0.673 0.673
MAX6888RETE 0.527 0.527 0.527 0.527 0.673 0.673 0.673 0.673
MAX6887/MAX6888
Hex/Quad, Power-Supply Supervisory Circuits
10 ______________________________________________________________________________________
OVERVOLTAGE
THRESHOLD
PRIMARY
THRESHOLD
OV
RESET
VIN
tOP
tRP
Figure 2. Output Timing Diagram
WDO
WDI
*tWDI IS THE INITIAL WATCHDOG TIMER PERIOD
tRP *tWDI *tWDI
tWD
tD-PO
RESET
VCC OR IN1–IN4
WDO NOT CONNECTED TO MR
2.5V
WDO
WDI
.
tRP *tWDI tWD tRP *tDWI
tD-PO
RESET
VCC OR IN1–IN4
WDO CONNECTED TO MR
2.5V
Figure 3. Watchdog, Reset, and Power-Up Timing Diagram
At power-up, WDO goes high after tD-PO (see Figure 3).
The initial watchdog timeout period (tWDI) applies imme-
diately after WDO is high. The initial watchdog timeout
period allows the µP to perform its initialization process.
A normal watchdog timeout period (tWD) applies when-
ever WDI transitions from high to low after the initial
watchdog timeout period occurs. WDI monitors the tog-
gling output of the µP, indicating normal processor
behavior. If WDI does not toggle during the normal
watchdog timeout period (tWD), indicating that the
processor has stopped operating or is stuck in an infinite
execution loop, WDO goes low. WDO stays low until the
next transition on WDI. An initial watchdog timeout peri-
od (tWDI) starts when WDO goes high.
If WDO is connected to MR, the WDO will assert for a
short duration (~5µs), long enough to assert the RESET
output. Asserting RESET clears the watchdog timer and
WDO goes high. The reset output will remain asserted
for its timeout period after a watchdog fault. The watch-
dog timer stays cleared as long as RESET is low.
Applications Information
Layout and Bypassing
For better noise immunity, bypass each of the voltage-
detector inputs to GND with 0.1µF capacitors installed
as close to the device as possible. Bypass VCC and BP
to GND with 1µF capacitors installed as close to the
device as possible. VCC (when not externally supplied)
and BP are internally generated voltages and should
not be used to supply power to external circuitry.
MAX6887/MAX6888
Hex/Quad, Power-Supply Supervisory Circuits
______________________________________________________________________________________ 11
Selector Guide (continued)
NOMINAL INPUT
VOLTAGE (V)*
PART
IN1 IN2 IN3 IN4
TOLERANCE
(%)
MAX6888AETE 5.0 3.3 2.5 1.8 5
MAX6888BETE 5.0 3.3 2.5 Adj 5
MAX6888CETE 5.0 3.3 1.8 Adj 5
MAX6888DETE 3.3 2.5 1.8 1.5 5
MAX6888EETE 3.3 2.5 1.8 Adj 5
MAX6888FETE 3.3 2.5 1.5 Adj 5
MAX6888GETE 3.3 2.5 Adj Adj 5
MAX6888HETE 3.3 1.8 Adj Adj 5
MAX6888QETE Adj Adj Adj Adj 5
MAX6888IETE 5.0 3.3 2.5 1.8 10
MAX6888JETE 5.0 3.3 2.5 Adj 10
MAX6888KETE 5.0 3.3 1.8 Adj 10
MAX6888LETE 3.3 2.5 1.8 1.5 10
MAX6888METE 3.3 2.5 1.8 Adj 10
MAX6888NETE 3.3 2.5 1.5 Adj 10
MAX6888OETE 3.3 2.5 Adj Adj 10
MAX6888PETE 3.3 1.8 Adj Adj 10
MAX6888RETE Adj Adj Adj Adj 10
*
See thresholds options tables (Tables 1 and 2) for actual under-
voltage and overvoltage thresholds.
Chip Information
PROCESS: BiCMOS
Package Information
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages. Note that a "+", "#", or "-" in
the package code indicates RoHS status only. Package draw-
ings may show a different suffix character, but the drawing per-
tains to the package regardless of RoHS status.
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
16-TQFN-EP T1655+2 21-0140
MAX6887/MAX6888
Hex/Quad, Power-Supply Supervisory Circuits
12 ______________________________________________________________________________________
MARGIN
VCC
WDI
WDO
OV
LOGIC OUTPUT
LOGIC INPUT
LOGIC INPUT
GND
VCC
GND
*MAX6887 ONLY
µP
DC-DC
1
BP
DC-DC
2DC-DC
3DC-DC
4
IN1 IN2 IN3 IN4
1.5V
IN5* IN6*
12V
MR
RESET RESET
12V
5V
3.3V
2.5V
1.8V
MAX6887
MAX6888
1.2V
Typical Operating Circuit
Pin Configurations
16
1234
12 11 10 9
15
14
13
5
6
7
8
IN1
IN2
IN3
IN4
IN5
IN6
BP
VCC
WDO
OV
GND
MR
MARGIN
WDI
I.C.
RESET
TOP VIEW
MAX6887
*EXPOSED PAD
THIN QFN
*EXPOSED PAD CONNECTED TO GND.
16
1234
12 11 10 9
15
14
13
5
6
7
8
IN1
IN2
IN3
IN4
N.C.
N.C.
BP
VCC
WDO
OV
GND
MR
MARGIN
WDI
I.C.
RESET
MAX6888
*EXPOSED PAD
THIN QFN
*EXPOSED PAD CONNECTED TO GND.
MAX6887/MAX6888
Hex/Quad, Power-Supply Supervisory Circuits
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________
13
© 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 5/05 Initial release —
1 3/07 Revised Pin Description. 1, 5, 14
2 1/10 Revised Ordering Information to add lead-free information and revised Table 2. 1, 9
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