General Description

The MAX5949A/MAX5949B are hot-swap controllers that

allow a circuit card to be safely hot plugged into a live

backplane. The MAX5949A/MAX5949B operate from

-20V to -80V and are well-suited for -48V power systems.

These devices are pin and function compatible with the

LT4250 and pin compatible with the LT1640.

The MAX5949A/MAX5949B provide a controlled turn-on

to circuit cards preventing glitches on the power-supply

rail and damage to board connectors and components.

The MAX5949A/MAX5949B provide undervoltage, over-

voltage, and overcurrent protection. These devices

ensure the input voltage is stable and within tolerance

before applying power to the load.

Both the MAX5949A and MAX5949B protect a system

against overcurrent and short-circuit conditions by turn-

ing off the external MOSFET in the event of a fault con-

dition. The MAX5949A/MAX5949B also provide

protection against input voltage steps. During an input

voltage step, the MAX5949A/MAX5949B limit the cur-

rent drawn by the load to a safe level without turning off

power to the load.

Both devices feature an open-drain power-good status

output (PWRGD for the MAX5949A or PWRGD for the

MAX5949B) that can be used to enable downstream

converters.

The MAX5949A/MAX5949B are available in an 8-pin SO

package. Both devices are specified for the extended

-40°C to +85°C temperature range.

Applications

Telecom Line Cards

Network Switches/Routers

Central-Office Line Cards

Server Line Cards

Base-Station Line Cards

Central-Office Switching

-48V Distributed Power Systems

Negative Power-Supply Controls

Features

♦ Allow Safe Board Insertion and Removal

from a Live -48V Backplane

♦ Pin and Function Compatible with LT4250L

(MAX5949A)

♦ Pin Compatible with LT1640L (MAX5949A)

♦ Pin and Function Compatible with LT4250H

(MAX5949B)

♦ Pin Compatible with LT1640H (MAX5949B)

♦ Circuit-Breaker Immunity to Input Voltage Steps

and Current Spikes

♦ Withstand -100V Input Transients with No

External Components

♦ Programmable Inrush and Short-Circuit Current

Limits

♦ Operate from -20V to -80V

♦ Programmable Overvoltage Protection

♦ Programmable Undervoltage Lockout

♦ Power Up into a Shorted Load

♦ Power-Good Control Output

-48V Hot-Swap Controllers

________________________________________________________________ Maxim Integrated Products

1

GATE

SENSE

1

2

8

7

DRAIN

OV

UV

PWRGD

(PWRGD)

SO

TOP VIEW

3

4

6

5

MAX5949A

MAX5949B

( ) FOR MAX5949B.

Pin Configuration

Ordering Information

19-3494; Rev 0; 11/04

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.

PART

TEMP RANGE

PIN-PACKAGE

MAX5949AESA

-40°C to +85°C

8 SO

MAX5949BESA

-40°C to +85°C

8 SO

Typical Operating Circuit and Selector Guide appear at end

of data sheet.