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19-1278; Rev 0; 8/97
2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown
_______________General Description
The MAX869L P-channel load switch features an accurate user-set current limit and low on-resistance. This switch is designed to protect your power source from shorts and surges by limiting current and preventing the system supply from being pulled low. The input voltage range is 2.7V to 5.5V. The MAX869L features a 2A, 45m switch controlled by a logic signal. Current-limit accuracy is 21%, and can be set from 400mA to 2.4A using a single resistor. The device has a low 12A quiescent supply current, which reduces to 2A max in shutdown. It features thermal-shutdown protection and a logic-signal output pin (FAULT) that signals when there is an overcurrent or overtemperature condition. For other devices in this family, consult the Selector Guide.
____________________________Features
o Very Small Footprint (16-pin QSOP is the same size as an 8-pin SO) o Low Resistance: 45m at 3V o 21%-Accurate, User-Set Current Limit o 12A (typ) Quiescent Current o 0.01A (typ) Shutdown Current o 0.04A (typ) Leakage to Output when Switch is Off o 2.7V to 5.5V Input Range o Thermal Shutdown o FAULT Output
MAX869L
_____________________Selector Guide
PART MAX869L MAX890L MAX891L MAX892L MAX894L MAX895L RON AT 3V (m) 45 90 150 300 150 300 NOMINAL CURRENT (A) 2 1 0.5 0.25 0.5 0.25 COUNT Single Single Single Single Dual Dual PACKAGE 16 QSOP 8 SO 8 MAX 8 MAX 8 SO 8 SO
______________Ordering Information
PART MAX869LC/D MAX869LEEE TEMP. RANGE 0C to +70C -40C to +85C PIN-PACKAGE Dice* 16 QSOP
*Dice are specified at TA = +25C.
__________Typical Operating Circuit
________________________Applications
Universal Serial Bus (USB) Notebook Computers Personal Communicators Palmtop Computers Hand-Held Instruments Portable Medical Instruments
INPUT 2.7V TO 5.5V 1F* 100k
IN
OUT
OUTPUT UP TO 2A 0.1F*
MAX869L
FAULT GND
ON SET
ON/OFF
RSET
Pin Configuration appears at end of data sheet.
*FOR USB APPLICATIONS, CIN = 1F, COUT = 120F
________________________________________________________________ Maxim Integrated Products
1
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2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown MAX869L
ABSOLUTE MAXIMUM RATINGS
IN to GND ..................................................................-0.3V to 6V ON, FAULT to GND ....................................................-0.3V to 6V SET, OUT to GND ...................................... -0.3V to (VIN + 0.3V) Maximum Continuous Switch Current .....................................3A Continuous Power Dissipation (TA = +70C) QSOP (derate 8.3mW/C above +70C) .......................667mW Operating Temperature Range MAX869LEEE.....................................................-40C to +85C Storage Temperature Range ........................... -65C to +150C Lead Temperature (soldering, 10sec) .............................+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
(VIN = 3V, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Operating Voltage Quiescent Current Off-Supply Current Off-Switch Current Undervoltage Lockout On-Resistance Nominal Current-Limit Set Range Current-Limit-Amplifier Threshold IOUT to ISET Current Ratio ON Input Low Voltage ON Input High Voltage ON Input Leakage ISET Bias Current FAULT Logic Output Low Voltage FAULT Logic Output High Leakage Current Slow-Current-Loop Response Time Fast-Current-Loop Response Time Turn-On Time Turn-Off Time VIN = 5V, IOUT = 500mA VIN = 3V, IOUT = 500mA VIN = 5V, IOUT = 500mA 2 VIN = 5V, ON = GND, IOUT = 0A ON = IN, VIN = VOUT = 5.5V ON = IN, VIN = 5.5V, VOUT = 0V Rising edge, 1% hysteresis VIN = 4.75V VIN = 3.0V RSET = 1% tolerance (Note 1) VSET required to turn the switch off (Note 2) IOUT = 1A, VOUT > 1.6V VIN = 2.7V to 5.5V VIN = 2.7V to 3.6V VIN = 4.5V to 5.5V V ON = 5.5V VSET = 1.24V, IOUT = 0A ISINK = 1mA, VSET = 1.4V V FAULT = 5.5V, VSET = 1V 20% current overdrive, VCC = 5V 0.05 10 4 100 200 10 30 300 2.0 2.4 0.01 0.05 1 3 0.4 1 0.40 1.178 810 1.240 955 2.0 CONDITIONS MIN 2.7 12 0.01 0.04 2.3 38 45 TYP MAX 5.5 20 2 30 2.6 70 90 2.4 1.302 1100 0.8 UNITS V A A A V m A V A/A V V A A V A s s s s
Note 1: Guaranteed by design. Derived from the ISET current ratio; current-limit amplifier and external set resistor accuracies. Note 2: Tested with IOUT = 200mA and VSET raised until (VIN - VOUT) 0.8V. Note 3: Specifications to -40C are guaranteed by design, not production tested.
2
_______________________________________________________________________________________
2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown
ELECTRICAL CHARACTERISTICS
(VIN = 3V, TA = -40C to +85C, unless otherwise noted.) (Note 3) PARAMETER Operating Voltage Quiescent Current Off-Supply Current Off-Switch Current Undervoltage Lockout On-Resistance Nominal Current-Limit Set Range Current-Limit-Amplifier Threshold IOUT to ISET Current Ratio FAULT Logic Output Low Voltage Turn-On Time Turn-Off Time VIN = 5V, ON = GND, IOUT = 0A ON = IN, VIN = VOUT = 5.5V ON = IN, VIN = 5.5V, VOUT = 0V Rising edge, 1% hysteresis VIN = 4.75V VIN = 3.0V RSET = 1% tolerance (Note 1) VSET required to turn the switch off (Note 2) IOUT = 1A, VOUT > 1.6V ISINK = 1mA, VSET = 1V VIN = 5V, IOUT = 500mA VIN = 5V, IOUT = 500mA 2 0.40 1.14 765 2.0 CONDITIONS MIN 2.9 TYP MAX 5.5 25 2.5 30 2.85 70 90 2.4 1.34 1145 0.4 400 30 UNITS V A A A V m A V A/A V s s
MAX869L
3
Note 1: Guaranteed by design. Derived from the ISET current ratio; current-limit amplifier and external set resistor accuracies. Note 2: Tested with IOUT = 200mA and VSET raised until (VIN - VOUT) 0.8V. Note 3: Specifications to -40C are guaranteed by design, not production tested.
_______________________________________________________________________________________
2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown MAX869L
__________________________________________Typical Operating Characteristics
(TA = +25C, unless otherwise noted.)
QUIESCENT CURRENT vs. INPUT VOLTAGE
MAX869-01
QUIESCENT CURRENT vs. TEMPERATURE
MAX869-02
OFF-SUPPLY CURRENT vs. TEMPERATURE
18 OFF-SUPPLY CURRENT (nA) 16 14 12 10 8 6 4 2 VIN = VOUT = 5.5V IN = ON
MAX869-03
14 12 QUIESCENT CURRENT (A) 10 8 6 4 2 0 0 1 2 3 4 5 6 INPUT VOLTAGE (V) ON = GND IOUT = 0A
14 13 12 VIN = 5V 11 10 9 8 -40 -20 0 20 40 60 80 VIN = 3V
20
QUIESCENT CURRENT (A)
0 100 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) TEMPERATURE (C)
OFF-SWITCH CURRENT vs. TEMPERATURE
MAX869-04
NORMALIZED ON-RESISTANCE vs. TEMPERATURE
MAX890-05
IOUT/ISET RATIO vs. SWITCH CURRENT
MAX890-06
700 600 OFF-SWITCH CURRENT (nA) 500 400 300 200 100 0 -40 -20 0 20 40 60 80 VIN = VON = 5.5V OUT = GND
1.4 1.3 1.2 NORMALIZED RON 1.1 1.0 0.9 0.8 0.7 0.6 IOUT = 1/2ILIMIT
1400 1200 IOUT/ISET RATIO 1000 800 600 400 200 0
100
-40
-20
0
20
40
60
80
100
0
0.4
0.8
1.2
1.6
2.0
2.4
2.8
TEMPERATURE (C)
TEMPERATURE (C)
ISWITCH (A)
NORMALIZED OUTPUT CURRENT vs. OUTPUT VOLTAGE
MAX869-06A
TURN-ON TIME vs. TEMPERATURE
260 240 220 200 180 160 140 120 100 80 60 40 20 0
MAX869-07
TURN-OFF TIME vs. TEMPERATURE
CIN = 100F COUT = 0.1F ILOAD = ILIMIT
MAX869-08
1.2 NORMALIZED OUTPUT CURRENT 1.0 0.8 ILIMIT
CIN = 100F COUT = 0.1F ILOAD = ILIMIT VIN = 3V
12 10 8 tOFF (s) VIN = 3V 6 4 2 0
VIN = 5V
0.6 0.4 0.2 VIN = 5V 0 0 1 2 3 4 5 6 OUTPUT VOLTAGE (V)
tON (s)
VIN = 5V
-40
-20
0
20
40
60
80
100
-40
-20
0
20
40
60
80
100
TEMPERATURE (C)
TEMPERATURE (C)
4
_______________________________________________________________________________________
2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown
____________________________Typical Operating Characteristics (continued)
(TA = +25C, unless otherwise noted.)
FAST CURRENT-LIMIT RESPONSE
MA869-09
MAX869L
SLOW CURRENT-LIMIT RESPONSE
A 0V B 0V
MA869-10
A 0V B 0V
C 0A D 0V 2s/div CIN = 100F, COUT = 0.1F C: IOUT, 5A/div A: VFAULT, 5V/div D: VIN, 5V/div B: VOUT, 5V/div
C 0A D 0V 4s/div CIN = 100F, COUT = 0.1F C: IOUT, 5A/div A: VFAULT, 5V/div D: VIN, 5V/div B: VOUT, 5V/div
LOAD-TRANSIENT RESPONSE
MA869-11
A 0A
0V B
10ms/div VIN = 5V A: IOUT = 0mA TO 1A, 0.5A/div B: VOUT RIPPLE, 200mV/div, AC COUPLED
SWITCH TURN-ON TIME
MA869-12
SWITCH TURN-OFF TIME
A 0V B
MA869-13
A 0V B
0V C 0A D 0V 20s/div CIN = 100F, COUT = 0.1F, VIN = 5V, IOUT = 1A C: IOUT, 0.5A/div A: VON, 5V/div D: VFAULT, 2V/div B: VOUT, 2V/div
C
0V 0A
D 0V 2s/div CIN = 100F, COUT = 0.1F, VIN = 5V, IOUT = 1A A: VON, 5V/div C: IOUT, 0.5A/div B: VOUT, 2V/div D: VFAULT, 2V/div
_______________________________________________________________________________________
5
2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown MAX869L
____________________________Typical Operating Characteristics (continued)
(TA = +25C, unless otherwise noted.) USB* CIRCUIT OUTPUT RISE TIME
MA869-14
USB* CIRCUIT OUTPUT FALL TIME
A 0V B
MA869-15
A 0V
B 0V C 0A C 0A 0V
D D 0V 500s/div VIN = 5V, IOUT = 1A, CIN = 1F, COUT = 120F A: VON, 5V/div C: IOUT, 0.5A/div B: VOUT, 2V/div D: VFAULT, 2V/div 0V 500s/div VIN = 5V, IOUT = 1A, CIN = 1F, COUT = 120F A: VON, 5V/div C: IOUT, 0.5A/div B: VOUT, 2V/div D: VFAULT, 2V/div
*REFER TO TYPICAL OPERATING CIRCUIT
_____________________Pin Description
PIN 1, 4, 5, 12, 13, 16 2, 3, 6, 11, 14, 15 7 8 NAME IN FUNCTION Input, P-channel MOSFET source. Bypass IN with a 1F capacitor to ground. Switch output. P-channel MOSFET drain. Bypass OUT with a 0.1F capacitor to GND. Active-Low Switch-On Input. A logic low turns the switch on. Ground Set Current-Limit Input. A resistor from SET to ground sets the current limit for the switch. RSET = 1,184 / ILIMIT, where ILIMIT is the desired current limit in amperes. Fault-Indicator Output. This opendrain output goes low when in current limit or when the die temperature exceeds +135C. FAULT remains low for Turn-On Time + 50s during startup.
_______________Detailed Description
The MAX869L P-channel MOSFET power switch limits output current to a programmed level. When the output current passes through the main switch, a smaller current also passes through the replica switch (IOUT / 955) and through RSET (Figure 1). When the voltage on RSET exceeds the trip voltage of 1.24V, the current-limit error amplifier regulates the output current to the programmed current limit, ILIMIT (400mA to 2.4A). This switch is not bidirectional; therefore, the input voltage must be higher than the output voltage.
OUT
ON GND
Setting the Current Limit
The MAX869L features internal current-limiting circuitry with a maximum programmable value (IMAX) of 2.4A. For best performance, set the current limit (I LIMIT ) between 0.2 IMAX ILIMIT IMAX. This current limit remains in effect throughout the input supply-voltage range. Program the current limit with a resistor (R SET) from SET to ground (Figure 2) as follows: ISET = ILIMIT / 955 RSET = 1.24V / ISET = 1,184 / ILIMIT where ILIMIT is the desired current limit.
9
SET
10
FAULT
6
_______________________________________________________________________________________
2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown MAX869L
IN P OUT
MAX869L
FAULT P
MAX869L
SET
N
REPLICA AMPLIFIER ON GND P SET ON CURRENT-LIMIT AMPLIFIER 1.24V
RSET
RSET
Figure 2. Setting the Current Limit
HOT ON CONTROL CIRCUITRY GND
Fault Indicator
The MAX869L provides a fault output (FAULT). This open-drain output goes low when in current limit or when the die temperature exceeds 135C. A 100k pull-up resistor from FAULT to IN provides a logiccontrol signal.
Figure 1. Functional Diagram
__________Applications Information
Short-Circuit Protection
The MAX869L is a short-circuit-protected switch. In the event of an output short circuit (VOUT 1.6V typical), the current through the switch is limited by the internal current-limiting error amplifier to 1.4 x ILIMIT. When the short-circuit condition is removed, the current-limit amplifier sets the current limit back to ILIMIT. For a high VDS/t during an output short-circuit condition, the switch turns off and disconnects the input supply from the output. The current-limiting amplifier then slowly turns the switch on with the output current limited to 1.4 x I LIMIT . When the short-circuit condition is removed, the current limit is set back to ILIMIT. Refer to the Fast Current-Limit Response and Slow Current-Limit Response graphs in the Typical Operating Characteristics.
Input Capacitor
To limit the input voltage drop during momentary output short-circuit conditions, connect a capacitor from IN to GND. A 1F ceramic capacitor is adequate for most applications; however, higher capacitor values further reduce the voltage drop at the input.
Output Capacitor
Connect a 0.1F capacitor from OUT to GND to prevent inductive parasitics from pulling OUT below GND during turn-off. USB applications require COUT to be at least 120F. This larger output capacitance slows the output rise and fall times, as shown in the Typical Operating Characteristics, but does not adversely affect the MAX869L's turn-off response time.
Thermal Shutdown
The MAX869L features thermal shutdown. The switch turns off when the junction temperature exceeds 135C. Once the device cools by 10C, the switch turns back on. If the fault condition is not removed, the switch cycles on and off, resulting in a pulsed output.
Layout and Thermal-Dissipation Considerations
To take full advantage of the switch-response time to output short-circuit conditions, it is very important to keep all traces as short as possible to reduce the effect of undesirable parasitic inductance. Place input and output capacitors as close as possible to the device (less than 5mm).
_______________________________________________________________________________________
7
2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown MAX869L
Under normal operating conditions, the package can dissipate and channel heat away. Calculate the maximum power as follows: P = I2LIMIT x RON where RON is the on-resistance of the switch. When the output is short circuited, the voltage drop across the switch equals the input supply. Hence, the power dissipated across the switch increases, as does the die temperature. If the fault condition is not removed, the thermal-overload-protection circuitry turns the switch off until the die temperature falls by 10C. A ground plane in contact with the device helps dissipate additional heat.
__________________Pin Configuration
TOP VIEW
IN 1 OUT 2 OUT 3 IN 4 IN 5 OUT 6 ON 7 GND 8 16 IN 15 OUT 14 OUT
___________________Chip Information
TRANSISTOR COUNT: 433 SUBSTRATE CONNECTED TO GND
MAX869L
13 IN 12 IN 11 OUT 10 FAULT 9 SET
QSOP
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.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 1997 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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