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19-0291; Rev 1; 3/07
Hex/Quad, Power-Supply Supervisory Circuits
General Description
The MAX6887/MAX6888 multivoltage supply supervisors provide several voltage-detector inputs, one watchdog 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, opendrain outputs. The MAX6887/MAX6888 are available in a 5mm x 5mm x 0.8mm, 16-pin thin QFN package and operate over the extended -40C to +85C temperature range. Hex/Quad Voltage Detectors Undervoltage and Overvoltage Thresholds 1% Threshold Accuracy Margining Disable and Manual Reset Input Watchdog Timer Open-Drain RESET, OV, and WDO Outputs 180ms (min) Reset Timeout Period Few External Components Small 5mm x 5mm, 16-Pin Thin QFN Packages
Features
MAX6887/MAX6888
Ordering Information
PART MAX6887_ETE MAX6888_ETE TEMP RANGE PINPACKAGE PKG CODE T1655-2 T1655-2
-40C to +85C 16 Thin QFN -40C to +85C 16 Thin QFN
Applications
Multivoltage Systems Telecom Networking Servers/Workstations/Storage Systems
Note: Insert the desired letter from the Selector Guide into the blank to complete the part number.
Pin Configurations and Typical Operating Circuit appear at end of data sheet.
Selector Guide
PART MAX6887AETE MAX6887BETE NOMINAL INPUT VOLTAGE (V)* IN1 5.0 5.0 IN2 3.3 3.3 3.3 2.5 2.5 2.5 2.5 1.8 Adj IN3 2.5 2.5 1.8 1.8 1.8 1.5 Adj Adj Adj IN4 1.8 Adj Adj 1.5 Adj Adj Adj Adj Adj IN5 Adj Adj Adj Adj Adj Adj Adj Adj Adj IN6 Adj Adj Adj Adj Adj Adj Adj Adj Adj TOL (%) 5 5 5 5 5 5 5 5 5 PART MAX6887IETE MAX6887JETE MAX6887KETE MAX6887LETE NOMINAL INPUT VOLTAGE (V)* IN1 5.0 5.0 5.0 3.3 IN2 3.3 3.3 3.3 2.5 2.5 2.5 2.5 1.8 Adj IN3 2.5 2.5 1.8 1.8 1.8 1.5 Adj Adj Adj IN4 1.8 Adj Adj 1.5 Adj Adj Adj Adj Adj IN5 Adj Adj Adj Adj Adj Adj Adj Adj Adj IN6 Adj Adj Adj Adj Adj Adj Adj Adj Adj TOL (%) 10 10 10 10 10 10 10 10 10
MAX6887CETE 5.0 MAX6887DETE 3.3 MAX6887EETE MAX6887FETE 3.3 3.3
MAX6887METE 3.3 MAX6887NETE 3.3 MAX6887OETE 3.3 MAX6887PETE MAX6887RETE 3.3 Adj
MAX6887GETE 3.3 MAX6887HETE 3.3 MAX6887QETE Adj
*See thresholds options tables (Tables 1 and 2) for actual undervoltage and overvoltage thresholds. Selector Guides continued at end of data sheet. ________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
Hex/Quad, Power-Supply Supervisory Circuits MAX6887/MAX6888
ABSOLUTE MAXIMUM RATINGS
(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 = +70C) 16-Pin 5mm x 5mm Thin QFN (derate 20.8mW/C above +70C) ..............................1667mW Maximum Junction Temperature .....................................+150C Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
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.
ELECTRICAL CHARACTERISTICS
(VIN1-VIN4 or VCC = 2.7V to 5.8V, WDI = GND, MARGIN = MR = BP, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Notes 1, 2)
PARAMETER Operating Voltage Range (Note 3) Supply Current Threshold Accuracy (See the Selector Guide) Threshold Hysteresis Threshold Tempco IN_ Input Impedance ICC VTH VTH-HYST VTH/C RIN For VIN_ < highest VIN1-IN4 and VIN_ < VCC (not ADJ), thresholds are not set as adjustable IN5, IN6 (MAX6887 only) IN1-IN4 set as adjustable thresholds VCC 2.5V IN_ falling/rising, 100mV overdrive 180 20 200 25 ISINK = 4mA, output asserted Output high impedance -1 0.4 +1 220 130 SYMBOL CONDITIONS Voltage on either one of IN1-IN4 or VCC to guarantee the part is fully operational VIN1 = 5.8V, IN2-IN6 = GND, no load IN1-IN6, IN_ falling, TA = +25C to +85C IN1-IN6, IN_ falling, TA = -40C to +85C -1 -1.5 0.3 10 200 300 MIN 2.7 0.9 TYP MAX 5.8 1.2 +1 +1.5 UNITS V mA % VTH % VTH ppm/C k
IN_ Input Leakage Current Power-Up Delay IN_ to RESET or OV Delay RESET Timeout Period OV Timeout Period RESET, OV, and WDO Output Low RESET, OV, and WDO Output Open-Drain Leakage Current
IIN tD-PO tD-R tRP tOP VOL ILKG
-150
+150 2.5
nA ms s ms s V A
2
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Hex/Quad, Power-Supply Supervisory Circuits
ELECTRICAL CHARACTERISTICS (continued)
(VIN1-VIN4 or VCC = 2.7V to 5.8V, WDI = GND, MARGIN = MR = BP, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Notes 1, 2)
PARAMETER MR, MARGIN, WDI Input Voltage MR Input Pulse Width MR Glitch Rejection MR to RESET or OV Delay MR to Internal BP Pullup Current MARGIN to Internal BP Pullup Current WDI Pulldown Current WDI Input Pulse Width Watchdog Timeout Period tWDI tWD Initial Normal tD-MR IMR IMARGIN IWDI VMR = 1.4V VMARGIN = 1.4V VWDI = 0.6V 5 5 5 50 92.16 1.44 102.4 1.6 112.64 1.76 SYMBOL VIL VIH tMR 1.4 1 100 200 10 10 10 15 15 15 CONDITIONS MIN TYP MAX 0.6 UNITS V s ns ns A A A ns s
MAX6887/MAX6888
Note 1: Note 2: Note 3: Note 4:
100% production tested at TA = +25C and TA = +85C. Specifications at TA = -40C are guaranteed by design. Device may be supplied from any one of IN1-IN4 or VCC. The internal supply voltage, measured at VCC, equals the maximum of IN1-IN4. Versions Q and R require that power be applied through VCC.
Typical Operating Characteristics
(VIN1-VIN4 or VCC = 5V, WDI = GND, MARGIN = MR = BP, TA = +25C, unless otherwise noted.)
VCC SUPPLY CURRENT vs. VCC SUPPLY VOLTAGE
MAX6887 toc01 MAX6887 toc02
IN1-IN4 SUPPLY CURRENT vs. IN1-IN4 SUPPLY VOLTAGE
1.00 0.95 SUPPLY CURRENT (mA) 0.90 0.85 0.80 0.75 0.70 2.6 3.6 4.6 5.6 SUPPLY VOLTAGE (V) TA = -40C TA = +25C 1.00 0.95 SUPPLY CURRENT (mA)
RESET TIMEOUT PERIOD vs. TEMPERATURE
215 TIMEOUT PERIOD (ms) 210 205 200 195 190 185 180
MAX6887 toc03
220
TA = +85C
TA = +85C 0.90 0.85 0.80 0.75 0.70 2.6 3.6 4.6 5.6 SUPPLY VOLTAGE (V) TA = -40C TA = +25C
-40
-15
10
35
60
85
TEMPERATURE (C)
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Hex/Quad, Power-Supply Supervisory Circuits MAX6887/MAX6888
Typical Operating Characteristics (continued)
(VIN1-VIN4 or VCC = 5V, WDI = GND, MARGIN = MR = BP, TA = +25C, unless otherwise noted.)
IN_ TO RESET OR OV PROPAGATION DELAY vs. TEMPERATURE
MAX6887 toc04
WATCHDOG TIMEOUT PERIOD vs. TEMPERATURE
MAX6887 toc05
NORMALIZED IN_ THRESHOLD vs. TEMPERATURE
1.004 NORMALIZED IN_ THRESHOLD 1.003 1.002 1.001 1.000 0.999 0.998 0.997 0.996 0.995
MAX6887 toc06
30 29 PROPAGATION DELAY (s) 28 27 26 25 24 23 22 21 20 -40 -15 10 35 60 100mV OVERDRIVE
1.700 1.675 TIMEOUT PERIOD (s) 1.650 1.625 1.600 1.575 1.550 1.525 1.500
1.005
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (C)
TEMPERATURE (C)
TEMPERATURE (C)
MAXIMUM IN_ TRANSIENT vs. IN_THRESHOLD OVERDRIVE
MAX6887 toc07
OUTPUT-VOLTAGE LOW vs. SINK CURRENT
MAX8667 toc08
MR TO RESET OUTPUT PROPAGATION DELAY vs. TEMPERATURE
2.75 PROPAGATION DELAY (s) 2.50 2.25 2.00 1.75 1.50 1.25 1.00
MAX6887 toc09
200 MAXIMUM TRANSIENT DURATION (s) 175 150 125 100 75 50 25 0 1 10 100 PO_ ASSERTION OCCURS ABOVE THIS LINE
400 350 OUTPUT-VOLTAGE LOW (mV) 300 250 200 150 100 50 0
3.00
1000
0
2
4
6
8
10
12
14
-40
-15
10
35
60
85
IN_ THRESHOLD OVERDRIVE (mV)
SINK CURRENT (mA)
TEMPERATURE (C)
Pin Description
PIN MAX6887 1 MAX6888 1 NAME FUNCTION 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. 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. Open-Drain Active-Low Overvoltage Output. OV asserts when any input voltage exceeds its overvoltage threshold. OV remains low for 25s after all overvoltage conditions are cleared. An external pullup resistor is required. Ground
RESET
2
2
WDO
3 4
3 4
OV GND
4
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Hex/Quad, Power-Supply Supervisory Circuits
Pin Description (continued)
PIN MAX6887 5 MAX6888 5 NAME FUNCTION 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 10A current source. 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 10A current source. Leave MARGIN unconnected or connect to BP if unused. MARGIN overrides MR if both are asserted at the same time. 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 10A current sink. Internal Connection. Leave unconnected. Internal Power-Supply Voltage. Bypass VCC to GND with a 1F 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. Bypass Voltage. The internally generated voltage at BP supplies power to internal logic and output RESET. Connect a 1F capacitor from BP to GND as close to the device as possible. Do not use BP to supply power to external circuitry. 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 0.1F capacitor installed as close to the device as possible. 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 0.1F capacitor installed as close to the device as possible. 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 0.1F capacitor installed as close to the device as possible. 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 0.1F capacitor installed as close to the device as possible. 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 0.1F capacitor installed as close to the device as possible. 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 0.1F capacitor installed as close to the device as possible. No Connection. Not internally connected. Exposed Paddle. Internally connected to GND. Connect EP to GND or leave unconnected.
MAX6887/MAX6888
MR
6
6
MARGIN
7 8
7 8
WDI I.C.
9
9
VCC
10
10
BP
11
--
IN6
12
--
IN5
13
13
IN4
14
14
IN3
15
15
IN2
16
16
IN1
-- --
11, 12 --
N.C. EP
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Hex/Quad, Power-Supply Supervisory Circuits MAX6887/MAX6888
Functional Diagram
WDI IN1 *IN_ DETECTOR MARGIN MR
RESET LOGIC ARRAY
IN2 IN3 IN4 IN5 (N.C.) IN6 (N.C.)
IN2 DETECTOR IN3 DETECTOR IN4 DETECTOR IN5 DETECTOR IN6 DETECTOR (VIRTUAL DIODES)
RESET TIMING BLOCK
OV
OV TIMING BLOCK
WDO
VCC 1F 2.55V LDO BP 1F
WDO TIMING BLOCK REFERENCE
MAX6887 MAX6888
( ) MAX6888 ONLY GND *FOR ADJUSTABLE INPUTS REFER TO THE ADJUSTABLE THRESHOLD INPUTS SECTION.
6
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Hex/Quad, Power-Supply Supervisory Circuits MAX6887/MAX6888
Detailed Description
The MAX6887/MAX6888 provide several supply-detector inputs, one watchdog input, and three outputs for powersupply 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 factory-set for monitoring standard supply voltages (see the Selector Guide). Inputs in the Selector Guide that contain "Adj" allow an external voltage-divider to be connected 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 25s (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 lowto-high or high-to-low. The MAX6887/MAX6888 generate a supply voltage at BP for the internal logic circuitry. Bypass BP to GND with a 1F 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 overvoltage 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 external voltage-divider to be connected to set a userdefined 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-
Powering the MAX6887/MAX6888
The MAX6887/MAX6888 derive power from the voltagedetector inputs IN1-IN4 or through an externally supplied 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 connection for the MAX6887/MAX6888 internal supply. Bypass V CC to GND with a 1F ceramic capacitor installed as close to the device as possible. The internal supply voltage, measured at VCC, equals the maximum 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.
VIN
R1 IN_
MAX6887 MAX6888
R2 *VREFUV
*VREFOV
*VREFOV AND VREFUV ARE REFERENCED TO 0.6V ACCORDING TO THE DEVICE'S TOLERANCE
Figure 1. Adjusting the Monitored Threshold
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Hex/Quad, Power-Supply Supervisory Circuits MAX6887/MAX6888
detector input (IN1-IN6) to monitor a user-defined supply voltage: R2 0.6V = VMON x R1+ R2 where VMON is the desired voltage to be monitored. Use the following procedure to design the proper voltage-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: V VACTUALUV = VMON x REFUV 0.6V V VACTUALOV = VMON x REFOV 0.6V VREFUV and VREFOV are the undervoltage and overvoltage thresholds listed in Tables 1 and 2 that allow adjustable thresholds. Their values are based on tolerances 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 P-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 10A current source. MR is designed to reject fast, falling transients (typically 100ns pulses) and MR must be held low for a minimum of 1s to assert RESET. Connect a 0.1F capacitor from MR to ground to provide additional noise immunity. After MR transitions from low to high, RESET remains asserted for the duration of its time delay. Margin Output Disable (MARGIN) MARGIN allows system-level testing while power supplies exceed the normal operating ranges. Drive MARGIN low to hold RESET, OV, and WDO in their
Table 1. MAX6887 Threshold Options
PART MAX6887AETE MAX6887BETE MAX6887CETE MAX6887DETE MAX6887EETE MAX6887FETE MAX6887GETE MAX6887HETE MAX6887QETE MAX6887IETE MAX6887JETE MAX6887KETE MAX6887LETE MAX6887METE MAX6887NETE MAX6887OETE MAX6887PETE MAX6887RETE UV THRESHOLDS (V) IN1 4.620 4.620 4.620 3.060 3.060 3.060 3.060 3.060 0.557 4.380 4.380 4.380 2.880 2.880 2.880 2.880 2.880 0.527 IN2 3.060 3.060 3.060 2.310 2.310 2.310 2.310 1.670 0.557 2.880 2.880 2.880 2.190 2.190 2.190 2.190 1.580 0.527 IN3 2.310 2.310 1.670 1.670 1.670 1.390 0.557 0.557 0.557 2.190 2.190 1.580 1.580 1.580 1.310 0.527 0.527 0.527 IN4 1.670 0.557 0.557 1.390 0.557 0.557 0.557 0.557 0.557 1.580 0.527 0.527 1.310 0.527 0.527 0.527 0.527 0.527 IN5 0.557 0.557 0.557 0.557 0.557 0.557 0.557 0.557 0.557 0.527 0.557 0.557 0.557 0.557 0.557 0.557 0.557 0.527 IN6 0.557 0.557 0.557 0.557 0.557 0.557 0.557 0.557 0.557 0.527 0.557 0.557 0.557 0.557 0.557 0.557 0.557 0.527 IN1 5.360 5.360 5.360 3.540 3.540 3.540 3.540 3.540 0.643 5.620 5.620 5.620 3.700 3.700 3.700 3.700 3.700 0.673 IN2 3.540 3.540 3.540 2.680 2.680 2.680 2.680 1.930 0.643 3.700 3.700 3.700 2.810 2.810 2.810 2.810 2.020 0.673 OV THRESHOLDS (V) IN3 2.680 2.680 1.930 1.930 1.930 1.610 0.643 0.643 0.643 2.810 2.810 2.020 2.020 2.020 1.680 0.673 0.673 0.673 IN4 1.930 0.643 0.643 1.610 0.643 0.643 0.643 0.643 0.643 2.020 0.673 0.673 1.680 0.673 0.673 0.673 0.673 0.673 IN5 0.643 0.643 0.643 0.643 0.643 0.643 0.643 0.643 0.643 0.673 0.673 0.673 0.673 0.673 0.673 0.673 0.673 0.673 IN6 0.643 0.643 0.643 0.643 0.643 0.643 0.643 0.643 0.643 0.673 0.673 0.673 0.673 0.673 0.673 0.673 0.673 0.673
8
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Hex/Quad, Power-Supply Supervisory Circuits MAX6887/MAX6888
Table 2. MAX6888 Threshold Options
PART MAX6888AETE MAX6888BETE MAX6888CETE MAX6888DETE MAX6888EETE MAX6888FETE MAX6888GETE MAX6888HETE MAX6888QETE MAX6888IETE MAX6888JETE MAX6888KETE MAX6888LETE MAX6888METE MAX6888NETE MAX6888OETE MAX6888PETE MAX6888RETE UV THRESHOLDS (V) IN1 4.620 4.620 4.620 3.060 3.060 3.060 3.060 3.060 0.527 4.380 4.380 4.380 2.880 2.880 2.880 2.880 2.880 0.557 IN2 3.060 3.060 3.060 2.310 2.310 2.310 2.310 1.670 0.527 2.880 2.880 2.880 2.190 2.190 2.190 2.190 1.580 0.557 IN3 2.310 2.310 1.670 1.670 1.670 1.390 0.557 0.557 0.527 2.190 2.190 1.580 1.580 1.580 1.310 0.527 0.527 0.557 IN4 1.670 0.557 0.557 1.390 0.557 0.557 0.557 0.557 0.527 1.580 0.527 0.527 1.310 0.527 0.527 0.527 0.527 0.557 IN1 5.360 5.360 5.360 3.540 3.540 3.540 3.540 3.540 0.673 5.620 5.620 5.620 3.700 3.700 3.700 3.700 3.700 0.643 OV THRESHOLDS (V) IN2 3.540 3.540 3.540 2.680 2.680 2.680 2.680 1.930 0.673 3.700 3.700 3.700 2.810 2.810 2.810 2.810 2.020 0.643 IN3 2.680 2.680 1.930 1.930 1.930 1.610 0.643 0.643 0.673 2.810 2.810 2.020 2.020 2.020 1.680 0.673 0.673 0.643 IN4 1.930 0.643 0.643 1.610 0.643 0.643 0.643 0.643 0.673 2.020 0.673 0.673 1.680 0.673 0.673 0.673 0.673 0.643
existing state while system-level testing occurs. Leave MARGIN unconnected or connect to BP if unused. An internal 10A 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 opendrain 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 overvoltage threshold and remains asserted until all inputs are below their thresholds and its respective 25s timeout 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 complete description. WDO requires a pullup resistor.
Configuring the Watchdog Timer
A watchdog timer monitors microprocessor (P) software execution for a stalled condition and resets the P if it stalls. Connect the watchdog timer output WDO to the reset input or a nonmaskable interrupt of the P. The watchdog timer features independent initial and normal watchdog timeout periods of 102.4s and 1.6s, respectively.
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Hex/Quad, Power-Supply Supervisory Circuits MAX6887/MAX6888
OVERVOLTAGE THRESHOLD VIN PRIMARY THRESHOLD
OV tOP
RESET tRP
Figure 2. Output Timing Diagram
2.5V . 2.5V VCC OR IN1-IN4 VCC OR IN1-IN4 WDO WDO RESET RESET WDI WDI tD-PO tRP *tWDI tWD *tWDI tD-PO tRP *tWDI WDO CONNECTED TO MR WDO NOT CONNECTED TO MR *tWDI IS THE INITIAL WATCHDOG TIMER PERIOD tWD tRP *tDWI
Figure 3. Watchdog, Reset, and Power-Up Timing Diagram
10
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Hex/Quad, Power-Supply Supervisory Circuits
At power-up, WDO goes high after tD-PO (see Figure 3). The initial watchdog timeout period (tWDI) applies immediately after WDO is high. The initial watchdog timeout period allows the P to perform its initialization process. A normal watchdog timeout period (tWD) applies whenever WDI transitions from high to low after the initial watchdog timeout period occurs. WDI monitors the toggling output of the P, indicating normal processor behavior. If WDI does not toggle during the normal watchdog timeout period (t WD ), 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 period (tWDI) starts when WDO goes high. If WDO is connected to MR, the WDO will assert for a short duration (~5s), 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 watchdog timer stays cleared as long as RESET is low.
Selector Guide (continued)
PART IN1 MAX6888AETE MAX6888BETE MAX6888CETE MAX6888DETE MAX6888EETE MAX6888FETE MAX6888GETE MAX6888HETE MAX6888QETE MAX6888IETE MAX6888JETE MAX6888KETE MAX6888LETE MAX6888METE MAX6888NETE MAX6888OETE MAX6888PETE MAX6888RETE 5.0 5.0 5.0 3.3 3.3 3.3 3.3 3.3 Adj 5.0 5.0 5.0 3.3 3.3 3.3 3.3 3.3 Adj NOMINAL INPUT VOLTAGE (V)* IN2 3.3 3.3 3.3 2.5 2.5 2.5 2.5 1.8 Adj 3.3 3.3 3.3 2.5 2.5 2.5 2.5 1.8 Adj IN3 2.5 2.5 1.8 1.8 1.8 1.5 Adj Adj Adj 2.5 2.5 1.8 1.8 1.8 1.5 Adj Adj Adj IN4 1.8 Adj Adj 1.5 Adj Adj Adj Adj Adj 1.8 Adj Adj 1.5 Adj Adj Adj Adj Adj 5 5 5 5 5 5 5 5 5 10 10 10 10 10 10 10 10 10 TOLERANCE (%)
MAX6887/MAX6888
Applications Information
Layout and Bypassing
For better noise immunity, bypass each of the voltagedetector inputs to GND with 0.1F capacitors installed as close to the device as possible. Bypass VCC and BP to GND with 1F 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.
*See thresholds options tables (Tables 1 and 2) for actual undervoltage and overvoltage thresholds.
Chip Information
PROCESS: BiCMOS
______________________________________________________________________________________
11
Hex/Quad, Power-Supply Supervisory Circuits MAX6887/MAX6888
Pin Configurations
N.C. N.C.
VCC
IN5
IN6
BP
12 IN4 13 IN3 14
11
10
9 IN4 13 IN3 14
12
11
10
VCC 9
TOP VIEW
BP
8 7
I.C. WDI MARGIN MR
8 7
I.C. WDI MARGIN MR
MAX6887
IN2 15 IN1 16 1 RESET 6 IN2 15 IN1 16 1 RESET
MAX6888
6
*EXPOSED PAD
2 WDO 3 OV 4 GND
5
*EXPOSED PAD
2 WDO 3 OV 4 GND
5
THIN QFN
*EXPOSED PAD CONNECTED TO GND.
THIN QFN
*EXPOSED PAD CONNECTED TO GND.
Typical Operating Circuit
12V DC-DC 1 DC-DC 2 DC-DC 3
12V 5V 3.3V 2.5V
DC-DC 4 1.5V 1.2V
1.8V
IN1 VCC
IN2
IN3
IN4
IN5*
IN6* OV WDO
VCC LOGIC INPUT LOGIC INPUT P RESET LOGIC OUTPUT GND
BP
MAX6887 MAX6888
RESET WDI MR
MARGIN GND
*MAX6887 ONLY
12
______________________________________________________________________________________
Hex/Quad, Power-Supply Supervisory Circuits
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
MAX6887/MAX6888
______________________________________________________________________________________
QFN THIN.EPS
13
Hex/Quad, Power-Supply Supervisory Circuits MAX6887/MAX6888
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
Revision History
Pages changed at Rev 1: 1, 5, 14
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.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

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