General Description

The MAX1940 triple current-limited switch with auto-

reset supplies a guaranteed 500mA load per channel in

accordance with USB specifications. The MAX1940

operates from a 4V to 5.5V input supply and consumes

only 60µA of quiescent current when operating and only

3µA in standby. Selectable active-high/active-low con-

trol logic and independent shutdown controls for each

channel provide additional flexibility. An autoreset fea-

ture latches the switch off in the event of a short circuit,

saving system power. The switch reactivates upon

removal of the shorted condition.

The MAX1940 provides several safety features to pro-

tect the USB port. Built-in thermal-overload protection

turns off the switch when the die temperature exceeds

+160°C. Accurate internal current-limiting circuitry pro-

tects the input supply against both overload and short-

circuit conditions. Independent open-drain fault signals

(FAULTA, FAULTB, and FAULTC) notify the micro-

processor when a thermal-overload, current-limit,

undervoltage lockout (UVLO), or short-circuit fault

occurs. A 20ms fault-blanking feature enables the cir-

cuit to ignore momentary faults, such as those caused

when hot-swapping a capacitive load, preventing false

alarms to the host system. The fault-blanking feature

also prevents fault signals from being issued when the

device powers up the load.

The MAX1940 is available in a space-saving 16-pin

QSOP package and operates over the extended (-40°C

to +85°C) temperature range.

Applications

Features

o Triple USB Switch in Tiny 16-Pin QSOP Package

o Autoreset Feature Saves System Power

o Guaranteed 500mA Load Current per Channel

o Built-In 20ms Fault-Blanking Circuitry

o Active-High/Active-Low Control Logic

o Fully Compliant to USB Specifications

o 4V to 5.5V Input Voltage Range

o Independent Shutdown Control

o Independent Fault Indicator Outputs

o Thermal-Overload Protection

o 3µA Standby Current

o UL Certification Pending

Triple USB Switch with Autoreset and

Fault Blanking

________________________________________________________________ Maxim Integrated Products

1

IN1

IN2

IN3

IN4

IN5

ONA

ONB

ONC

SEL

FAULTA

FAULTB

FAULTC

OUTA

OUTB

OUTC

GND

MAX1940

INPUT

4V TO 5.5V

USB

PORT A

USB

PORT B

USB

PORT C

ACTIVE-HIGH/ACTIVE-LOW

SELECTABLE

Typical Operating Circuit

Ordering Information

19-2497; Rev 0; 7/02

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.

PART

TEMP RANGE

PIN-PACKAGE

MAX1940EEE

-40°C to +85°C

16 QSOP

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

ONA

FAULTA

OUTA

GND

OUTB

FAULTB

SEL

OUTC

FAULTC

TOP VIEW

MAX1940

QSOP

IN1

IN2

IN4

IN3

ONB

IN5

ONC

Pin Configuration

USB Ports

USB Hubs

Notebook Computers

Desktop Computers

PDAs and Palmtop

Computers

Docking Stations