A

B

A

2B

V(DS)

Detector

Enable

Constant

Power

Engine

_

+

50mVmax

Charge

Pump

22 A

m

GateControl

Amplifier

4V

Reference

14V

2mA

+

−

+

−

I(D)

Detector

_

+

9mS

Deglitch

Inrush

Complete

Power/Current

Amplifier

25 A

m

Fault

Logic

_

+

4V

and

1V

2.5 A

m

Timer

For AutoretryOptionwith

DutyCycleof0.75%

_

+

_

+

UVLO

Enable

POR

8.4Vand

8.3V

1.35Vand

1.25V

10

VCC

3

PROG

9

SENSE

1

EN

5

GND

4

TIMER

6

PG

7

OUT

8

GATE

2

VREF

2.7Vand

1.25V

Enable

10

TPS2490, TPS2491

SLVS503E – NOVEMBER 2003 – REVISED FEBRUARY 2017

www.ti.com

Product Folder Links: TPS2490 TPS2491

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Copyright © 2003–2017, Texas Instruments Incorporated

7 Detailed Description

7.1 Overview

The inline protection functionality of the TPS2490 is designed to control the inrush current to the load upon

insertion of a circuit card into a live backplane or other hot power source, thereby limiting the voltage sag on the

backplane's supply voltage and the dV/dt of the voltage applied to the load. Effects on other circuits in the

system are minimized, preventing possible unintended resets. A controlled shutdown when the circuit card is

removed can also be implemented using the TPS2490.

In addition to a programmable current limit, the TPS2490 monitors and limits the maximum power dissipation in

the series pass device to maintain operating within the device Safe Operating Area (SOA). Either current limiting

or power limiting for an extended period of time results in the shutdown of the series pass device. In this event,

the TPS2490 will latch off while the TPS2491 will retry an infinite number of timer to recover after the fault is

removed. Programmable EN circuit shuts down the TPS2490 when the system input voltage falls below the

desired operating range.

7.2 Functional Block Diagram