General Description

The MAX5943 is a fully integrated power-management

external power n-channel MOSFETs to regulate current

from the input power supply to the load and performs

low-voltage-drop, power-supply ORing. The MAX5943

operates over a 7.5V to 37V input range and provides

inrush and output current limit in addition to a diode

ORing function suitable for FireWire applications.

The MAX5943 allows the safe insertion and removal of

FireWire peripherals into a live FireWire port by providing

inrush current control and an output current-limiting func-

tion. The ORing feature provides a very efficient way to

protect the FireWire port when connected to another

FireWire peripheral that sources a higher voltage. By turn-

ing off both external MOSFETS, the MAX5943 provides a

true bidirectional load disconnect. A low-current shut-

down mode disables the MAX5943, resulting in less than

10µA supply current. A pin-selectable input allows

latched or autoretry fault management after a fault.

The MAX5943A features a current-limit function that

actively limits the current drawn by the load with a pro-

grammable timeout. The MAX5943B–MAX5943E do not

actively limit the load current but provide a circuit-breaker

function. See the Selector Guide for the default and pro-

grammable circuit-breaker timeouts.

The MAX5943 operates over the -40°C to +85°C extended

temperature range and is available in a 16-pin QSOP

package.

Applications

FireWire Desktop/Notebook Port

FireWire Peripheral Device Current Limit

FireWire Hub

Hot Swap

Features

♦ Provides Safe Hot Swap for 7.5V to 37V Power

Supplies

♦ Low-Drop Power ORing with Ultra-Fast Turn-Off

♦ Programmable Active Current Limit (MAX5943A)

♦ Programmable Circuit Breaker

(MAX5943B–MAX5943E)

♦ ±5% Current-Limit Sensing Accuracy

♦ Programmable Current-Limit/Circuit-Breaker

Timeout

♦ Fast Current-Limit Response to Output Short-

Circuit Conditions (MAX5943A)

♦ Drives External N-Channel Power MOSFETs

♦ Overcurrent Fault Status Output

♦ Latched or Autoretry Overcurrent Fault

Management

♦ 10µA Shutdown Current

♦ ON/OFF Control Allows Undervoltage Lockout

Programming

♦ Fast Load Disconnect Control Through ON Input

FireWire Current Limiter and Low-Drop

ORing Switch Controller

________________________________________________________________ Maxim Integrated Products

1

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

ON

IN

SENSE

GATE1

N.C.

GATE2

OUT

N.C.

GND

TOP VIEW

MAX5943

QSOP

FAULT

TIM

OR_ADJ

ILIM

LATCH

N.C.

ONQ1

Pin Configuration

Ordering Information

19-3378; Rev 0; 8/04

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.

Typical Operating Circuit and Selector Guide appear at end

of data sheet.

FireWire is a registered trademark of Apple Computers, Inc.

PART

TEMP RANGE

PIN-PACKAGE

MAX5943AEEE

-40

°C to +85°C

16 QSOP

MAX5943BEEE

-40

°C to +85°C

16 QSOP

MAX5943CEEE

-40

°C to +85°C

16 QSOP

MAX5943DEEE

-40

°C to +85°C

16 QSOP

MAX5943EEEE

-40

°C to +85°C

16 QSOP