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19-1518; Rev 0; 9/99
USB Current-Limited Switches with Fault Blanking
General Description
The MAX1693/MAX1694 are current-limited, 60m switches with built-in fault blanking. Their accurate preset current limit of 0.7A to 1.0A makes them ideally suited for USB applications. Their low quiescent supply current (14A) and shutdown current (1A) conserve battery power in portable applications. The MAX1693/ MAX1694 operate with inputs from +2.7V to +5.5V, making them ideal for both +3V and +5V systems. A fault signal notifies the microprocessor that the internal current limit has been reached. A 10ms fault-blanking feature allows momentary faults (such as those caused when hot-swapping into a capacitive load) to be ignored, thus preventing false alarms to the host system. This fault blanking also prevents a fault signal from being issued when the device is powering up. In the MAX1693, an output overcurrent condition causes the switch to current limit at 0.7A to 1.0A and FAULT to go low after the 10ms blanking period. When the overcurrent condition is removed, FAULT returns to its high-impedance state. In the MAX1694, any overcurrent longer than 10ms will latch the switch open and set FAULT low. The latch is cleared by cycling the ON input or by powering up the device again. This feature saves power by preventing the device from thermally cycling on and off in case of a persistent short-circuit condition. The MAX1693/MAX1694 have several safety features to ensure that the USB port is protected. Built-in thermaloverload protection limits power dissipation and junction temperatures. Both devices have accurate internal current-limiting circuitry to protect the input supply against overload. They are available in space-saving 10-pin MAX packages.
Features
o Accurate Current Limit (0.7A min, 1.0A max) o Guaranteed 0.75A Short-Circuit Protection o 10ms Internal Fault-Blanking Timeout o No Fault Signal During Power-Up o Latched FAULT Output Turns Off Power Switch (MAX1694) o Thermal Shutdown Protection o +2.7V to +5.5V Supply Range o 14A Supply Current o Small 10-Pin MAX Package o UL Recognition Pending
MAX1693/MAX1694
Applications
USB Ports and Hubs Notebook Computers Portable Equipment Docking Stations Hot Plug-In Power Supplies Battery-Charger Circuits
Ordering Information
PART MAX1693EUB MAX1694EUB TEMP. RANGE -40C to +85C -40C to +85C PIN-PACKAGE 10 MAX 10 MAX
Typical Operating Circuit Pin Configuration
INPUT +2.7V TO +5.5V IN OUT OUTPUT
TOP VIEW
IN 1 OUT IN OUT ON 2 3 4 5 10 OUT 9 IN OUT FAULT GND ON OFF ON GND FAULT
MAX1693 MAX1694
MAX1693 MAX1694
8 7 6
MAX
________________________________________________________________ Maxim Integrated Products
1
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USB Current-Limited Switches with Fault Blanking MAX1693/MAX1694
ABSOLUTE MAXIMUM RATINGS
IN, ON, FAULT to GND.............................................-0.3V to +6V OUT to GND ................................................-0.3V to (VIN + 0.3V) Maximum Continuous Switch Current .....1.2A (internally limited) OUT Short Circuit to GND ..........................................Continuous Continuous Power Dissipation (TA = +70C) 10-Pin MAX (derate 5.6mW/C above +70C) ............444mW Operating Temperature Range MAX1693EUB/MAX1694EUB ..........................-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 = +5V, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Operating Voltage Quiescent Current Off-Supply Current Undervoltage Lockout Off-Switch Leakage UVLO SYMBOL VIN IQ V ON = GND, IOUT = 0 Timer not running Timer running 2.0 0.01 CONDITIONS MIN 2.7 14 35 0.001 1 2.6 2 A TA = 0C to +85C VIN = 4.4V to 5.5V VIN = 4.4V to 5.5V VIN = 3V 700 72 850 500 60 15 90 125 150 1000 700 0.8 2 2.4 1 0.4 1 7 10 1 80 3 6 165 200 20 13 mA mA V V A V A ms ms s s C m TYP MAX 5.5 25 UNITS V A A V
V ON = VIN = VOUT = 5.5V Rising edge, 100mV hysteresis V ON = VIN, VIN = 5.5V, VOUT = GND TA = +25C RON ILIMIT ISC VIL VIH TA = +25C
On-Resistance Current Limit Continuous Short-Circuit Current Limit ON Input Logic Low Voltage ON Input Logic High Voltage ON Input Leakage FAULT Output Logic Low Voltage FAULT Output High Leakage Current Fault-Blanking Timeout Period Start-Up Time Switch Turn-On Time Switch Turn-Off Time Thermal Shutdown Threshold
TA = 0C to +85C (Note 1)
OUT shorted to GND, MAX1693 only (Note 2) VIN = 2.7V to 5.5V VIN = 2.7V to 3.6V VIN = 3.7V to 5.5V V ON = VIN or GND
VOL
ISINK = 1mA, VIN = 3V VIN = V FAULT = 5.5V
tFB
From overcurrent condition to FAULT assertion VIN = 5V, COUT = 150F, RL = 15, from ON driven low to 50% full VOUT
tON tOFF
ILOAD = 400mA ILOAD = 400mA
2
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USB Current-Limited Switches with Fault Blanking
ELECTRICAL CHARACTERISTICS
(VIN = +5V, TA = -40C to +85C, unless otherwise noted.) (Note 3) PARAMETER Operating Voltage Quiescent Current Off-Supply Current Undervoltage Lockout Off-Switch Leakage On-Resistance Current Limit Continuous Short-Circuit Current Limit ON Input Logic Low Voltage ON Input Logic High Voltage ON Input Leakage FAULT Output Logic Low Voltage FAULT Output High Leakage Current Fault-Blanking Timeout Period Switch Turn-On Time Switch Turn-Off Time tFB tON tOFF VOL VIL VIH RON ILIMIT UVLO SYMBOL VIN IQ V ON = GND, IOUT = 0, timer not running V ON = VIN = VOUT = 5.5V Rising edge, 100mV hysteresis V ON = VIN = 5.5V, VOUT = GND VIN = 4.4V to 5.5V VIN = 3V (Note 1) OUT shorted to GND, MAX1693 only (Note 2) VIN = 3V to 5.5V VIN = 3V to 3.6V VIN = 3.7V to 5.5V V ON = VIN or GND ISINK = 1mA, VIN = 3V VIN = V FAULT = 5.5V From overcurrent condition to FAULT assertion ILOAD = 400mA ILOAD = 400mA 1 6 2 2.4 1 0.4 1 14 200 20 640 2.0 CONDITIONS MIN 3 TYP MAX 5.5 25 2 2.9 15 125 150 1060 750 0.8 UNITS V A A V A m mA mA V V A V A ms s s
MAX1693/MAX1694
3
Note 1: MAX1693's current limit is tested by forcing VOUT to 4.5V. The MAX1694's current limit is tested by increasing the output current until the switch is latched off. Note 2: This specification applies to the MAX1693 only. The MAX1694 latches the switch off under a sustained (>10ms) shortcircuit condition. Note 3: Specifications to -40C are guaranteed by design, not production tested.
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USB Current-Limited Switches with Fault Blanking MAX1693/MAX1694
Typical Operating Characteristics
(VIN = +5V, TA = +25C, unless otherwise noted.)
OFF-SUPPLY CURRENT vs. TEMPERATURE
VON = VIN OFF-SUPPLY CURRENT (nA) 10
MAX1693/4 toc03
QUIESCENT CURRENT vs. INPUT VOLTAGE
MAX1693/4 toc01
QUIESCENT CURRENT vs. TEMPERATURE
VIN = 5V 15 QUIESCENT CURRENT (A) 14 13 12 11 10 9 0.01 -40 -20 0 20 40 60 80 100 -40 -20 TEMPERATURE (C) VIN = 3V
MAX1693/4 toc02
16 14 QUIESCENT CURRENT (A) 12 10 8 6 4 2 0 0 1 2 3 4 5 6 INPUT VOLTAGE (V) VON = GND IOUT = O
16
100
1
0.1
0 20 40 60 TEMPERATURE (C)
80
100
OFF-SWITCH CURRENT vs. TEMPERATURE
MAX1693/4 toc04
NORMALIZED ON-RESISTANCE vs. TEMPERATURE
MAX1693/4 toc05
NORMALIZED OUTPUT CURRENT vs. OUTPUT VOLTAGE
ILIMIT
MAX1693/4 toc06
1000 V0N = VIN OFF-SWITCH CURRENT (nA) 100
1.4 IOUT = 425mA 1.2 NORMALIZED RON 1.0 0.8 0.6 0.4
1.2 NORMALIZED OUTPUT CURRENT 1.0 0.8 SHORT-CIRCUIT CURRENT 0.6 0.4 0.2 0
10
1
0.1 0.2 0.01 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) 0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
0
1
2
3
4
5
6
OUTPUT VOLTAGE (V)
TURN-ON TIME vs. TEMPERATURE
MAX1693/4 toc07
TURN-OFF TIME vs. TEMPERATURE
ILOAD = 425mA VIN = 5V
MAX1693/4 toc08
FAULT-BLANKING TIMEOUT vs. TEMPERATURE
MAX1693/4 toc09
160 ILOAD = 425mA 140 120 100 tON (s) 80 60 40 20 0 -40 -20 0 20 40 60 80 VIN = 5V VIN = 3V
7 6 5 tOFF (s) 4 3 2 1 0
12 FAULT-BLANKING TIMEOUT (ms) 10 8 6 4 2 0 IOUT = 850mA VIN = 3V OR 5V -40 -20 0 20 40 60 80
VIN = 3V
100
-40
-20
0
20
40
60
80
100
100
TEMPERATURE (C)
TEMPERATURE (C)
TEMPERATURE (C)
4
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USB Current-Limited Switches with Fault Blanking
Typical Operating Characteristics (continued)
(VIN = +5V, TA = +25C, unless otherwise noted.)
MAX1693 CURRENT-LIMIT AND FAULT RESPONSE
MAX1693/4 toc10
MAX1693/MAX1694
MAX1693 CURRENT-LIMIT RESPONSE
1
MAX1693/4 toc11
1
2
2
3
3
4 2ms/div CH1 = VIN, 200mV/div, AC-COUPLED; CH2 = VOUT, 5V/div; CH3 = VFAULT, 5V/div; CH4 = IOUT, 500mA/div
4 10s/div CH1 = VIN, 200mV/div, AC-COUPLED; CH2 = VOUT, 5V/div; CH3 = VFAULT, 5V/div; CH4 = IOUT, 1A/div
MAX1693 SWITCH TURN-ON TIME
MAX1693/4 toc13
MAX1693 SWITCH TURN-OFF TIME
MAX1693/4 toc14
1 2
1 2
3
3
4 20s/div CH1 = VOUT, 5V/div; CH2 = VON, 5V/div; CH3 = VFAULT, 5V/div; CH4 = IOUT, 200mA/div
4 1s/div CH1 = VOUT, 5V/div; CH2 = VON, 5V/div; CH3 = VFAULT, 5V/div; CH4 = IOUT, 200mA/div
MAX1694 OVERCURRENT TO FAULT AND SWITCH LATCHED OFF
MAX1693/4 toc15
MAX1693 START-UP TIME (TYPICAL USB APPLICATION)
1
MAX1693/4 toc16
1
CL = 150F RL = 15 FULL-CURRENT LIMIT CHARGES CAPACITOR RESISTOR LOAD CURRENT
2
2
3 3 4 2ms/div CH1 = VFAULT, 5V/div; CH2 = IOUT, 5V/div; CH3 = IOUT, 1A/div
FOLDBACKCURRENT LIMIT
1ms/div CH1 = VOUT, 5V/div; CH2 = VON, 5V/div; CH3 = IOUT, 500mA/div; CH4 = VFAULT, 5V/div
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USB Current-Limited Switches with Fault Blanking MAX1693/MAX1694
Pin Description
PIN 1, 3, 9 2, 4, 8, 10 5 6 7 NAME IN OUT ON GND FAULT FUNCTION Input. P-channel MOSFET source. Connect all IN pins together and bypass with a 1F ceramic capacitor to ground. Switch Output. P-channel MOSFET drain. Connect all OUT pins together and bypass with a 0.1F capacitor to ground. Active-Low Switch On Input. A logic low turns the switch on. Ground Fault-Indicator Output. This open-drain output goes low when the device is in thermal shutdown or undervoltage lockout or on a sustained (>10ms) current-limit condition. For the MAX1694 only, this output latches low when asserted, and the power switch is turned off until the latch is reset.
These switches are not bidirectional; therefore, the input voltage must be higher than the output voltage.
IN P OUT
Continuous Short-Circuit Protection
The MAX1693/MAX1694 are foldback short circuit-protected switches. In the event of an output short-circuit or current-overload condition, the current through the switch is foldback-current limited to 500mA continuous for the MAX1693. For the MAX1694, if the short circuit lasts longer than 10ms, the switch is latched off.
MAX1693
FAULT P
N
REPLICA AMPLIFIER ON P
Thermal Shutdown
The MAX1693/MAX1694 feature thermal shutdown. The switch turns off and the FAULT output goes low immediately (no fault blanking) when the junction temperature exceeds +165C. The MAX1694 remains latched with the switch off and the FAULT output low. When the MAX1693 cools 20C, the switch turns back on. If the fault short-circuit condition is not removed, the switch will cycle on and off, resulting in a pulsed output.
GND
ON
10ms TIMER HOT ON CONTROL CIRCUITRY
CURRENT-LIMIT AMPLIFIER 1.24V
FAULT Indicator
The MAX1693/MAX1694 provide a fault output (FAULT). A 100k pull-up resistor from FAULT to IN provides a logic control signal. This open-drain output goes low when any of the following conditions occur: * The input voltage is below the undervoltage-lockout (UVLO) threshold. * The die temperature exceeds the thermal shutdown temperature limit of +165C. * The device is in current limit and the 10ms faultblanking period is exceeded.
Figure 1. MAX1693 Functional Diagram
_______________Detailed Description
The MAX1693/MAX1694 P-channel MOSFET power switches limit output current to 0.7A min to 1.0A max. When the output current is increased beyond the current limit (ILIMIT), the current also increases through the replica switch (IOUT/6500). The current-limit error amplifier compares the voltage to the internal 1.24V reference and regulates the current back to the ILIMIT.
6
Fault Blanking
The MAX1693/MAX1694 feature 10ms fault blanking. Fault blanking allows current-limit faults, including
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USB Current-Limited Switches with Fault Blanking
momentary short-circuit faults that occur when hotswapping a capacitive load, and also ensures that no fault is issued during power-up. When a load transient causes the device to enter current limit, an internal counter starts. If the load fault persists beyond the 10ms fault-blanking timeout, the FAULT output asserts low. Ensure that the MAX1693/MAX1694's input is adequately bypassed to prevent input glitches from triggering spurious FAULT outputs. Input voltage glitches less than 150mV will not cause a spurious FAULT output. Load-transient faults less than 10ms (typ) will not cause a FAULT output assertion. Only current-limit faults are blanked. Die overtemperature faults and input voltage droops below the UVLO threshold will cause an immediate fault output.
Layout and Thermal Dissipation
To optimize the switch-response time to output shortcircuit 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 to the device as possible (no more than 5mm). All IN and all OUT pins must be connected with short traces to the power bus. Wide power bus planes will provide superior heat dissipation through the switch IN and OUT pins. Figure 3 shows suggested pin connections for a single-layer board. Under normal operating conditions, the package can dissipate and channel heat away. Calculate the maximum power dissipation as follows: P = (ILIMIT)2 * RON where ILIMIT is the preset current limit (1.0A max) and RON is the on-resistance of the switch (125m max). When the output is short-circuited, foldback-current limiting activates and the voltage drop across the switch equals the input supply. The power dissipated across the switch increases, as does the die temperature. If the fault condition is not removed, the thermal-overload-protection circuitry activates (see the Thermal Shutdown section). Wide power-bus planes connected to IN and OUT and a ground plane in contact with the device will help dissipate additional heat.
MAX1693/MAX1694
Fault Latching (MAX1694 Only)
The MAX1694 features a latched FAULT output. Whenever the FAULT output is activated, it latches the FAULT output low and also turns the switch off. To clear the latch, either cycle the ON input or cycle the input voltage below UVLO.
Applications Information
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 will be adequate for most applications; however, higher capacitor values will further reduce the voltage drop at the input. See Figure 2.
Chip Information
TRANSISTOR COUNT: 715
Output Capacitor
Connect a 0.1F capacitor from OUT to GND. This capacitor helps prevent inductive parasitics from pulling OUT negative during turn-off.
INPUT +2.7V TO +5.5V 1F 100k
IN
OUT
OUTPUT 0.1F*
MAX1693 MAX1694
1 2 3 IN OUT IN OUT ON OUT IN OUT FAULT GND 10 9 8 7 6
MAX1693 MAX1694
FAULT
OFF ON ON GND
4 5
*USB SPECIFICATIONS REQUIRE A LARGER CAPACITOR
Figure 2. Typical Application Circuit
Figure 3. IN and OUT Cross Connections for a Single-Layer Board
7
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USB Current-Limited Switches with Fault Blanking MAX1693/MAX1694
Package Information
10LUMAX.EPS
Note: Neither the MAX1693 nor MAX1694 has an exposed pad.
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) 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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