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19-1791; Rev 0; 10/00
Micropower Adjustable Overvoltage Protection Controllers
General Description
The MAX1807/MAX1808 monitor up to five supply rails for an overvoltage condition and provide a latched output when any one of the five supplies exceeds the trip thresholds. The latched output drives an external Pchannel load switch to remove power when an overvoltage condition is detected. The latch is reset when a logic low is input to ON or the power supply is cycled. The MAX1807 provides a 28V open-drain fault output that can be used to trigger an alert, trip a resetable fuse, or for other purposes. The MAX1808 includes a low-battery comparator with hysteresis to drive the DP output high, turning off the external P-channel switch when the input voltage is too low. The MAX1807/MAX1808 are available in a miniature 10pin MAX package.
Features
o Five 3% Accurate Overvoltage Comparators o Series PFET Gate Driver with VGS Limiter o 21A Quiescent Supply Current o 4A Shutdown Current o 4.4V to 28V Operating Voltage Range o 3% Accurate Comparator with 10% Hysteresis for Low-Battery Detection (MAX1808) o 28V Open-Drain N-Channel Output (MAX1807) o Small 10-Pin MAX Package
MAX1807/MAX1808
________________________Applications
Notebook Computers Power-Supply Modules Multi-Output Power Supplies
PART MAX1807EUB MAX1808EUB
Ordering Information
TEMP. RANGE -40C to +85C -40C to +85C PIN-PACKAGE 10 MAX 10 MAX
Pin Configuration and Typical Operating Circuit appear at end of data sheet.
Functional Diagram
VDD ON 1V REF TH (MAX1808) + _ + _ + _ + _ + _ + _ 2.5V INTERNAL SUPPLY REF OK POWER-ON RESET (60s)
PMOS POWER DRIVER
DP
IN1 IN2 IN3 IN4 IN5
R S
Q FAULT (MAX1807)
MAX1807 MAX1808
GND
________________________________________________________________ Maxim Integrated Products
1
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Micropower Adjustable Overvoltage Protection Controllers MAX1807/MAX1808
ABSOLUTE MAXIMUM RATINGS
IN1_, TH to GND.......................................................-0.3V to +6V ON, VDD, FAULT to GND........................................-0.3V to +30V DP to GND..................................................-0.3V to (VDD + 0.3V) Continuous Power Dissipation 10-Pin MAX (derate 5.6mW/C above +70C)...........448mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C 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
(VDD = VON = 15V, VIN1-VIN5 = 0.5V, VTH = 2.0V, CDP = 5nF, FAULT = open, TA = 0C to +85C, unless otherwise noted.)
PARAMETER GENERAL VDD Input Voltage Range VDD Operating Voltage Range VDD Undervoltage Lockout Threshold Supply Current Shutdown Current COMPARATORS (IN1-IN5, TH) IN1-IN5 Input Trip Level TH Input Trip Level, Falling TH Input Trip Level, Rising IN1-IN5 Propagation Delay Rising edge, typical 1% hysteresis, VDD = 4.4V to 28V VDD = 4.4V to 28V (MAX1808 only) VDD = 4.4V to 28V (MAX1808 only) IN1-IN5 rising, 10mV overdrive, VDD = 4.4V TH rising, 10mV overdrive, VDD = 4.4V (MAX1808 only) TH Propagation Delay TH falling, 10mV overdrive, VDD = 4.4V (MAX1808 only) IN1-IN5 Input Leakage Current TH Input Leakage Current ON Input High Logic Level ON Input Low Logic Level ON Input Leakage Current FAULT Output High Leakage Current FAULT Output Low Voltage VIN = 1.5V VTH = 1.5V (MAX1808 only) VDD = 4.4V to 28V VDD = 4.4V to 28V VON = 5V VON = 28V V FAULT = 28V (MAX1807 only) ISINK = 4mA (MAX1807 only) 0.01 0.03 1.6 0.5 1.2 10 2 0.4 40 0.5 0.5 50 50 nA nA V V A A V 0.97 0.97 1.045 1 1 1.1 40 11 s 1.03 1.03 1.155 V V V s Rising trip level, typical 2% hysteresis; when VDD is below this level, DP = Hi and FAULT = Hi-Z VTH = 2V or 0.5V VDD = 15V, VON = GND, VIN1-VIN5 = VTH = GND DP and FAULT in correct state (Table 1) 2 4.4 2 2.7 21 4 28 28 4.0 45 8.5 V V V A A SYMBOL CONDITIONS MIN TYP MAX UNITS
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Micropower Adjustable Overvoltage Protection Controllers
ELECTRICAL CHARACTERISTICS (continued)
(VDD = VON = 15V, VIN1-VIN5 = 0.5V, VTH = 2.0V, CDP = 5nF, FAULT = open, TA = 0C to +85C, unless otherwise noted.)
PARAMETER DP Source Current (PMOS Turn-Off) DP Sink Current (PMOS Turn-On) DP Pullup Current (PMOS Off) DP Turn-On Clamp Voltage (VDD - VDP) SYMBOL VON = VDD, VIN1 = 1.5V VDP = VDD - 5V VDP = VDD - 2V, VON = GND, in shutdown state VON = VDD, IDPSINK = 10A VDD = 8.5V to 28V VDD = 4.4V 7.5 3.4 CONDITIONS VDP = VDD - 0.4V VDP = VDD - 2V MIN 1 5 4 TYP 50 20 50 25 9.5 4.1 11.5 4.4 MAX UNITS A mA mA A V
MAX1807/MAX1808
ELECTRICAL CHARACTERISTICS
(VDD = VON = 15V, VIN1-VIN5 = 0.5V, VTH = 2.0V, CDP = 5nF, FAULT = open, TA = -40C to +85C, unless otherwise noted.) (Note 1)
PARAMETER GENERAL VDD Input Voltage Range VDD Operating Voltage Range VDD Undervoltage Lockout Threshold Supply Current Shutdown Current COMPARATORS (IN1-IN5, TH) IN1-IN5 Input Trip Level TH Input Trip Level, Falling TH Input Trip Level, Rising IN1-IN5 Input Leakage Current TH Input Leakage Current ON Input High Logic Level ON Input Low Logic Level ON Input Leakage Current FAULT Output High Leakage Current FAULT Output Low Voltage DP Source Current (PMOS Turn-Off) DP Sink Current (PMOS Turn-On) DP Turn-On Clamp Voltage (VDD - VDP) Rising edge, typical 1% hysteresis VDD = 4.4V to 28V (MAX1808 only) VDD = 4.4V to 28V (MAX1808 only) VIN = 1.5V VTH = 1.5V (MAX1808 only) VDD = 4.4V to 28V VDD = 4.4V to 28V VON = 5V VON = 28V V FAULT = 28V (MAX1807 only) ISINK = 4mA (MAX1807 only) VON = VDD, VIN1 = 1.5V VDP = VDD - 5V VON = VDD, IDPSINK = 10A VDD = 8.5V to 28V VDD = 4.4V VDP = VDD - 0.4V VDP = VDD - 2V 1 4 2 7.5 3.4 11.5 4.4 1.8 0.4 1.2 10 2 0.4 0.95 0.95 1.045 1.05 1.05 1.155 50 50 V V V nA nA V V A A V A mA mA V Rising trip level, typical 2% hysteresis; when VDD is below this level, DP = Hi and FAULT = Hi-Z VTH = 2V or 0.5V VDD = 15V, VON = GND, VIN1-VIN5 = VTH = GND DP and FAULT in correct state (Table 1) 2 4.4 2 28 28 4.0 45 8.5 V V V A A SYMBOL CONDITIONS MIN TYP MAX UNITS
Note 1: Specifications to -40C are guaranteed by design, not production tested. _______________________________________________________________________________________ 3
Micropower Adjustable Overvoltage Protection Controllers MAX1807/MAX1808
Typical Operating Characteristics
(Typical Operating Circuit, VDD = 15V, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX1807 toc01
SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX1807 toc02
FAULT OUTPUT VOLTAGE LOW vs. FAULT OUTPUT SINK CURRENT
TA = +85C 600 OUTPUT VOLTAGE (mV) 500 400 300 200 TA = -40C 100 0 TA = +25C
MAX1807 toc03
25
5.0 SHUTDOWN SUPPLY CURRENT (A) 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 TA = -40C TA = +25C TA = +85C
TA = +85C
700
20 SUPPLY CURRENT (A) TA = -40C TA = +25C
15
10
5
0 0 5 10 15 20 25 30 SUPPLY VOLTAGE (V)
0 0 5 10 15 20 25 30 SUPPLY VOLTAGE (V)
0
4
8
12
16
20
FAULT OUTPUT SINK CURRENT (mA)
NORMALIZED IN_ TRIP THRESHOLD ERROR vs. SUPPLY VOLTAGE
0.20 TRIP THRESHOLD ERROR (%) 0.15 0.10 0.05 0 -0.05 -0.10 -0.15 -0.20 -0.25 0 5 10 15 20 25 30 SUPPLY VOLTAGE (V) TA = +85C TA = -40C TA = +25C
MAX1807 toc04
NORMALIZED IN_ TRIP THRESHOLD ERROR vs. TEMPERATURE
MAX1807 toc05
NORMALIZED TH TRIP THRESHOLD ERROR vs. SUPPLY VOLTAGE (TH FALLING)
MAX1807 toc06
0.25
0.3 0.2 TRIP THRESHOLD ERROR (%) 0.1 28V 0 15V -0.1 -0.2 -0.3 -0.4 -50 0 50 4.4V
0.02
TRIP THRESHOLD ERROR (%)
0.01 TA = +85C 0 TA = +25C
-0.01 TA = -40C -0.02
100
0
10
20
30
TEMPERATURE (C)
SUPPLY VOLTAGE (V)
NORMALIZED TH TRIP THRESHOLD ERROR vs. TEMPERATURE (TH FALLING)
MAX1807 toc07
NORMALIZED TH TRIP THRESHOLD ERROR vs. SUPPLY VOLTAGE (TH RISING)
MAX1807 toc08
NORMALIZED TH TRIP THRESHOLD ERROR vs. TEMPERATURE (TH RISING)
0.15 TRIP THRESHOLD ERROR (%) 0.10 0.05 0 -0.05 -0.10 -0.15 -0.20 4.4V
MAX1807 toc09
0.15 0.10 0.05 28V 0
0.3 0.2 0.1 0 -0.1 TA = +85C -0.2 -0.3 TA = +25C TA = -40C
0.20 28V
TRIP THRESHOLD ERROR (%)
-0.05 -0.10 -0.15 -50 0 50 100 TEMPERATURE (C) 4.4V
TRIP THRESHOLD ERROR (%)
0
5
10
15
20
25
30
-50
0
50
100
SUPPLY VOLTAGE (V)
TEMPERATURE (C)
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Micropower Adjustable Overvoltage Protection Controllers
Typical Operating Characteristics (continued)
(Typical Operating Circuit, VDD = 15V, TA = +25C, unless otherwise noted.)
MAX1807/MAX1808
IN_ PROPAGATION DELAY vs. SUPPLY VOLTAGE
MAX1807 toc10
TH PROPAGATION DELAY vs. SUPPLY VOLTAGE (TH FALLING)
MAX1807 toc11
TH PROPAGATION DELAY vs. SUPPLY VOLTAGE (TH RISING)
14 PROPAGATION DELAY (s) 12 10 8 6 4 2 0 30 0 5 10 15 20 25 30 SUPPLY VOLTAGE (V) 10mV OVERDRIVE TA = +25C TA = -40C
MAX1807 toc12
60 50 PROPAGATION DELAY (s) 40 30 20 10 0 0 5 10 15 20 TA = -40C
60 50 PROPAGATION DELAY (s) TA = +85C 40 TA =+25C 30 20 10 0 TA = -40C
16 TA = +85C
TA = +85C TA = +25C
10mV OVERDRIVE 25 30
10mV OVERDRIVE 0 5 10 15 20 25
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
DP SOURCE CURRENT vs. (VDD - VDP) VOLTAGE
MAX1807 toc14
DP SOURCE CURRENT vs. (VDD - VDP) VOLTAGE
MAX1807 toc13
DP SINK CURRENT vs. (VDD - VDP) VOLTAGE
MAX1807 toc15
0.10 0.09 0.08 SOURCE CURRENT (mA) 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 0 0.15 0.30 0.45
25
60 50 DP SINK CURRENT (mA) 40 30 20 10 0
20 SOURCE CURRENT (mA)
15
10
5
0 0.60 0 2 4 6 8 10 12 (VDD - VDP) VOLTAGE (V) (VDD - VDP) VOLTAGE (V)
0
2
4
6
8
10
12
(VDD - VDP) VOLTAGE (V)
IN_ AND TH BIAS CURRENT vs. TEMPERATURE
MAX1807 toc16
IN_ MAXIMUM TRANSIENT PULSE DURATION vs. PULSE OVERDRIVE VOLTAGE
MAX1807 toc17
TH MAXIMUM TRANSIENT PULSE DURATION vs. PULSE OVERDRIVE VOLTAGE
90 80 PULSE DURATION (s) 70 60 50 40 30 20 10 NEGATIVEGOING TRANSIENT DP GOES HIGH MOMENTARILY ABOVE THE CURVE
MAX1807 toc18
1.6 1.4 1.2 BIAS CURRENT (nA) 1.0 0.8 0.6 0.4 0.2 0 -40 -15 10 35 60
100 90 80 PULSE DURATION (s) 70 60 50 40 30 20 10 DP LATCHES (HIGH) ABOVE THE CURVE
100
85
0 0.001
0.01
0.1
1
0 0.001
0.01
0.1
1
TEMPERATURE (C)
OVERDRIVE VOLTAGE (V)
OVERDRIVE VOLTAGE (V)
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Micropower Adjustable Overvoltage Protection Controllers MAX1807/MAX1808
Pin Description
PIN 1-5 6 7 NAME IN1-IN5 GND ON FUNCTION Overvoltage Detect Comparator Input. When any input exceeds 1V, the fault latch is set. Connect unused inputs to GND. Ground Logic Input. ON turns on internal reference when high. Logic trip level is approximately 1.2V with 15% hysteresis. When ON is low, the fault latch is reset. ON can be connected directly to VDD at the expense of supply current. External P-Channel MOSFET Gate Driver Output. The output high level is VDD. The output low level is VDD - 9.5V or GND, whichever is higher. This output is latched high when an overvoltage condition is detected. Analog Supply Input. Use an external RC filter to eliminate excessive switching noise on VDD. When VDD is less than 2.7V, the fault latch is reset. Signal Overvoltage Condition Output. This open-drain N-channel output is latched low when an overvoltage condition is detected. (MAX1807 only) Input Monitor Comparator. When TH is below 1V, DP goes high to turn off the external P-channel switch. When TH exceeds 1.1V, DP goes low if there is no fault. Between 1V and 1.1V is the hysteresis band where the output state of the TH comparator remains unchanged. (MAX1808 only)
8
DP
9
VDD FAULT
10
TH
Detailed Description
The MAX1807/MAX1808 provide overvoltage protection for systems with multiple supply rails. Very low output voltage supplies can have an overvoltage before the power-supply controller has sufficient supply voltage to activate protection circuitry. The MAX1807/MAX1808 offer a system-wide approach to effectively protect the loads and prevent catastrophic events. The MAX1807/MAX1808 are powered directly by the main system input supply. A low output voltage from DP activates a P-channel switch to supply power to the rest of the system. As the rest of the system supplies come up, the MAX1807/MAX1808 monitor each of them for overvoltage conditions and safely disconnect the input from the rest of the system if any supply malfunctions occur due to a shorted MOSFET, shorted copper trace, or malfunctioning supply. Built-in overvoltage detectors in individual power supplies provide redundancy. The MAX1807/MAX1808 drive the main P-channel load switch that powers the system. The driver includes active clamping to safely drive a 12V P-channel MOSFET gate. If overvoltage is detected, the P-channel load switch is turned off and the state is latched. The internal fault latch resets when VDD is less than 2.7V (power cycled) or ON is pulled low (manual reset). When ON is logic low, the P-channel switch is turned off (Table 1).
6
The MAX1808 has a TH input that turns off the P-channel switch if TH goes below 1V without affecting the fault latch. TH output is designed for low-battery detection. The comparator has 10% hysteresis, allowing the battery voltage to rise when the load is removed without reenabling the external P-channel switch. The MAX1807 has a fault alert output (FAULT) instead of the TH input. FAULT is an open-drain output, rated for up to 28V, that directly reflects the state of the internal fault latch.
IN1-IN5 Overvoltage Comparators
The overvoltage comparators have a 1V trip level. The fault latch is set if any one of the five overvoltage comparators goes above the trip level. A limited input bandwidth ensures that small glitches will not trigger an overvoltage event (see IN_ Maximum Transient Pulse Duration vs. Pulse Overdrive Voltage in the Typical Operating Characteristics).
DP PFET Driver Output
The MAX1807/MAX1808 have a totem driver (DP) with an active clamp that simplifies driving the external Pchannel load switch. The -9.5V Vgs clamp eliminates complexity in circuits where VDD exceeds the P-channel FET's maximum gate voltage. DP goes high and turns off the P-channel switch during undervoltage lockout, when ON is low, when TH is less than 1V, or if an overvoltage fault occurs.
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Micropower Adjustable Overvoltage Protection Controllers
The DP driver can sink and source significant current and achieves fast turn-on and turn-off times even with large P-channel switches. Adding a resistor in series with DP can increase turn-on and turn-off times. To slow the turn-on time without affecting the turn-off time, add a diode in parallel with the resistor (Figure 1). The turnon time will be the product of the series resistor and the gate-to-source capacitance of the P-channel FET: tON = Cgs R The turn-off time will be the product of the gate-tosource capacitance of the P-channel FET and the DP source current of the MAX1807/MAX1808 (see DP Source Current vs. (VDD - VDP) Voltage in the Typical Operating Characteristics). For very slow turn-off times, adding an external capacitor between the gate and the source of the P-channel FET eliminates the need for resistors with extremely high values.
VDD DP R MAX1807 MAX1808 SYSTEM POWER SUPPLIES
disconnected from the battery. The comparator has a limited bandwidth to ensure that small transients will not shut down the system supplies. Increase TH hysteresis by adding a resistor from TH to one of the voltage rails disconnected by the P-channel load switch, such as the 1.8V supply (Figure 2). Use one of the lower voltage supplies to eliminate the necessity of extremely large resistors to obtain reasonable hysteresis. When the MAX1714 is on, the trip threshold is lower than when the MAX1714 is off, pro-
MAX1807/MAX1808
1N4148
TH Input Comparator (MAX1808 Only)
TH input comparator can disconnect the load from the battery when the battery voltage is too low. The falling trip level is 1V, and the rising trip level is 1.1V. The 100mV hysteresis can prevent the load switch from turning on when the battery voltage rises as the load is
Figure 1. External FET Gate Control
2V TO 28V 6.5M TH 1M MAX1808
2V TO 28V 6.5M DP TH 1M MAX1808 MAX1714 GND 10M 1.8V OR 0
VDD
VDD DP
GND
DEFAULT 10% HYSTERESIS VTRIP = 1V + (1A x 6.5M) = 7.5V VUNTRIP = 1.1V + (1.1A x 6.5M) = 8.25V
ADDING HYSTERESIS VTRIP = 1V + [1A (1.8V - 1.0V) / 10M] 6.5M = 1V + (1A - 0.08A) 6.5M = 1V + (920nA 6.5M) = 6.98V VUNTRIP = 1.1V + [1.1A - (0 - 1.1V) / 10M] 6.5M = 1.1V + (1.1A + 0.11A) 6.5M = 1.1V + (1.21A 6.5M) = 8.97V
Figure 2. Adding Hysteresis
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Micropower Adjustable Overvoltage Protection Controllers MAX1807/MAX1808
Table 1. MAX1807/MAX1808 State Table
VDD <2V 2 < VDD < 4.0V >4.0V >4.0V >4.0V >4.0V ON X X 0 1 1 1 TH X X X <1V >1.1V >1.1V IN1-IN5 X X X X All <1V Any >1V DP HI HI HI LO HI Hi-Z LO FAULT Hi-Z Hi-Z Note that TH has 0.1V hysteresis (MAX1808 only) Only condition for PFET to be turned on COMMENT Undefined Undefined
viding additional hysteresis. Turning off the chosen supply will change the undervoltage trip levels.
Pin Configuration
TOP VIEW
FAULT Open-Drain N-Channel Flag Output (MAX1807 Only)
The MAX1807 has an open-drain N-channel FAULT output. The FAULT output directly reflects the state of the internal fault latch, going low when an overvoltage event occurs. The FAULT output can be used to signal the system power-management microcontroller, trip a resetable fuse, drive an external high-side driver, or for other purposes.
IN1 1 IN2 IN3 IN4 IN5 2 3 4 5
10 FAULT (TH) 9 VDD DP ON GND
MAX1807 MAX1808
8 7 6
Undervoltage Lockout and Power-On Reset (POR) Period
Undervoltage lockout holds DP high and FAULT in high impedance until VDD exceeds the VDD undervoltage lockout threshold. When VDD exceeds the undervoltage threshold, the DP and FAULT outputs remain unchanged during the power-on reset period (60s), allowing the reference and comparators to settle. Normal operation resumes after the POR period.
( ) MAX1808 0NLY
MAX
Chip Information
TRANSISTOR COUNT: 955 PROCESS: BiCMOS
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Micropower Adjustable Overvoltage Protection Controllers
Typical Operating Circuit
MAX1807/MAX1808
5V 6.5M VDD 1M 0.01F 1M IN1 TH DP 402k 3.3V
2.5V 1.8V CORE
MAX1808
IN2 IN3 IN4 150k 682k
ON GND IN5 150k 121k
150k 150k
150k 261k THRESHOLDS: 1) 3.63V 2) 5.5V 3) 1.85V 4) 2.0V 5) 2.75V
150k
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Micropower Adjustable Overvoltage Protection Controllers MAX1807/MAX1808
Package Information
10LUMAX.EPS 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.
10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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