Charge

Pump

Driver

UVLO

Current

Limit

Thermal

Sense

IN

GND

EN

ILIM

OUT

FAULT

CS

Reverse

Voltage

Comparator

-

+

Current

Sense

(Note A)

8-ms Deglitch

Copyright © 2016, Texas Instruments Incorporated

13

TPS2552, TPS2553, TPS2552-1, TPS2553-1

www.ti.com

SLVS841F – NOVEMBER 2008 – REVISED AUGUST 2016

Product Folder Links: TPS2552 TPS2553 TPS2552-1 TPS2553-1

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Copyright © 2008–2016, Texas Instruments Incorporated

9 Detailed Description

9.1 Overview

The TPS255x and TPS255x-1 are current-limited, power-distribution switches using N-channel MOSFETs for

applications where short circuits or heavy capacitive loads are encountered and provide up to 1.5 A of

continuous load current. These devices allow the user to program the current-limit threshold between 75 mA and

1.7 A (typical) through an external resistor. Additional device shutdown features include overtemperature

protection and reverse-voltage protection. The device incorporates an internal charge pump and gate drive

circuitry necessary to drive the N-channel MOSFET. The charge pump supplies power to the driver circuit and

provides the necessary voltage to pull the gate of the MOSFET above the source. The charge pump operates

from input voltages as low as 2.5 V and requires little supply current. The driver controls the gate voltage of the

power switch. The driver incorporates circuitry that controls the rise and fall times of the output voltage to limit

large current and voltage surges and provides built-in soft-start functionality. There are two device families that

handle overcurrent situations differently. The TPS255x family enters constant-current mode while the TPS255x-1

family latches off when the load exceeds the current-limit threshold.

9.2 Functional Block Diagram

A.

TPS255x parts enter constant current mode during current limit condition; TPS255x-1 parts latch off

9.3 Feature Description

9.3.1 Overcurrent Conditions

The TPS255x and TPS255x-1 respond to overcurrent conditions by limiting their output current to the IOS levels

shown in Figure 23. When an overcurrent condition is detected, the device maintains a constant output current

and reduces the output voltage accordingly. Two possible overload conditions can occur.

The first condition is when a short circuit or partial short circuit is present when the device is powered-up or

enabled. The output voltage is held near zero potential with respect to ground and the TPS255x ramps the

output current to IOS. The TPS255x devices limits the current to IOS until the overload condition is removed or the

device begins to thermal cycle. The TPS255x-1 devices will limit the current to IOS until the overload condition is

removed or the internal deglitch time (7.5-ms typical) is reached and the device is turned off. The device remains

off until power is cycled or the device enable is toggled.