Datasheet

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General Description

The MAX1931 is a current-limited, 60mΩ switch with

built-in fault blanking. Its accurate preset current limit of

0.64A to 1.06A makes it ideally suited for USB applica-

tions. The device’s low quiescent supply current (14µA)

and shutdown current (1µA) conserve battery power in

portable applications. The MAX1931 operates with

inputs from 2.7V to 5.5V, making it ideal for both 3V and

5V systems.

A fault signal notifies the microprocessor that the inter-

nal current limit has been reached. A 10ms fault-blank-

ing 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 MAX1931, an output overcurrent condition causes

the switch to current limit at 0.64A to 1.06A and FAULT

to go low after the 10ms blanking period. When the

overcurrent condition is removed, FAULT returns to its

high-impedance state.

The MAX1931 has several safety features to ensure that

the USB port is protected. Built-in thermal overload

protection limits power dissipation and junction tempera-

tures. The device has an accurate internal current-limit-

ing circuitry to protect the input supply against overload.

The MAX1931 is available in a space-saving 10-pin

µMAX package.

Applications

USB Ports and Hubs

Notebook Computers

Portable Equipment

Docking Stations

Hot Plug-In Power Supplies

Battery-Charger Circuits

Features

♦ 0.5A Guaranteed Output Current

♦ Guaranteed 0.75A Short-Circuit Protection

♦ 10ms Internal Fault-Blanking Timeout

♦ No Fault Signal During Power-Up

♦ Thermal Shutdown Protection

♦ 2.7V to 5.5V Supply Range

♦ 14µA Supply Current

♦ Small 10-Pin µMAX Package

MAX1931

Current-Limited Switch for Single USB Port

_______________________________________________________________ Maxim Integrated Products 1

MAX1931

OUTPUT

OUT

INPUT

2.7V TO 5.5V

OFF

GND

FAULT

OUT

FAULTOUT

OUT

MAX1931

MAX

TOP VIEW

GNDON

Typical Operating Circuit

19-2357; Rev 0; 4/02

Pin Configuration

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.

Ordering Information

PART TEMP RANGE PIN-PACKAGE

MAX1931EUB -40°C to +85°C 10µMAX

Summary of content (8 pages)

PAGE 1
9-2357; Rev 0; 4/02 Current-Limited Switch for Single USB Port Features ♦ 0.5A Guaranteed Output Current ♦ Guaranteed 0.75A Short-Circuit Protection ♦ 10ms Internal Fault-Blanking Timeout ♦ No Fault Signal During Power-Up ♦ Thermal Shutdown Protection ♦ 2.7V to 5.
PAGE 2
MAX1931 Current-Limited Switch for Single USB Port ABSOLUTE MAXIMUM RATINGS IN, ON (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 = +70°C) 10-Pin µMAX (derate 5.6mW/°C above +70°C) ............444mW Operating Temperature Range ......
PAGE 3
Current-Limited Switch for Single USB Port MAX1931 ELECTRICAL CHARACTERISTICS (VIN = 5V, TA = -40°C to +85°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL Operating Voltage VIN Quiescent Current IQ Off Supply Current Undervoltage Lockout UVLO Off Switch Leakage On-Resistance RON Current Limit ILIMIT Continuous Short-Circuit Current Limit ON Input Logic Low Voltage ON Input Logic High Voltage MIN MAX UNITS 5.5 V V ON = GND, IOUT = 0, timer not running 35 µA V ON = VIN = VOUT = 5.
PAGE 4
Typical Operating Characteristics (VIN = 5V, TA = +25°C, unless otherwise noted.) 10 8 6 4 14 MAX1931 toc03 VON (ON) = VIN (GND) OFF SUPPLY CURRENT (nA) 15 QUIESCENT CURRENT (µA) VIN = 3V 13 12 11 10 1 0.1 10 0.01 1 2 3 4 5 -40 6 -20 V0N (ON) = VIN (GND) 60 80 100 0 20 40 60 TEMPERATURE (°C) NORMALIZED ON-RESISTANCE vs. TEMPERATURE NORMALIZED OUTPUT CURRENT vs. OUTPUT VOLTAGE IOUT = 425mA 1.2 NORMALIZED RON 100 40 1.
PAGE 5
Current-Limited Switch for Single USB Port 8 MAX1931 toc10 MAX1931 toc09 10 CURRENT-LIMIT RESPONSE CURRENT-LIMIT AND FAULT RESPONSE 1 1 2 2 3 3 4 4 6 4 2 IOUT = 850mA VIN = 3V OR 5V -40 -20 2ms/div 10µs/div TEMPERATURE (°C) CH1 = VIN, 200mV/div, AC-COUPLED; CH2 = VOUT, 5V/div; CH3 = VFAULT, 5V/div; CH4 = IOUT, 500mA/div CH1 = VIN, 200mV/div, AC-COUPLED; CH2 = VOUT, 5V/div; CH3 = VFAULT, 5V/div; CH4 = IOUT, 1A/div SWITCH TURN-ON TIME SWITCH TURN-OFF TIME STARTUP TIME (TYPICAL USB APPL
PAGE 6
Current-Limited Switch for Single USB Port MAX1931 Pin Description PIN NAME FUNCTION Input. P-channel MOSFET source. Connect all IN pins together and bypass with a 1µF ceramic capacitor to ground. 1, 3, 9 IN 2, 4, 8, 10 OUT Switch Output. P-channel MOSFET drain. Connect all OUT pins together and bypass with a 0.1µF capacitor to ground. 5 ON Active-Low Switch On Input. A logic low turns the switch on. 6 GND 7 FAULT Ground Fault-Indicator Output.
PAGE 7
Current-Limited Switch for Single USB Port Applications Information Input Capacitor To limit the input voltage drop during momentary output short-circuit conditions, connect a capacitor from IN to GND. A 1µF ceramic capacitor is adequate for most applications; however, higher capacitor values further reduce the voltage drop at the input (see Figure 2). Output Capacitor Connect a 0.1µF capacitor from OUT to GND. This capacitor helps prevent inductive parasitics from pulling OUT negative during turn-off.
PAGE 8
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.) 10LUMAX.EPS MAX1931 Current-Limited Switch for Single USB Port Note: MAX1931 does not have 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.