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AUTO-RETRY FUNCTIONALITY

OUT

IN

GND

FAULT

ILIM

EN

Input

TPS2551

PowerPad

Output

0.1 F

m

R

100k

FAULT

W

C

0.1 F

RETRY

m

R

20k

ILIM

W

1kW

OUT

IN

GND

FAULT

ILIM

EN

ExternalLogic

Signal&Driver

TPS2551

PowerPad

Input

0.1 F

m

R

100k

FAULT

W

C

0.1 F

RETRY

m

R

20k

ILIM

W

1kW

Output

LATCH-OFF FUNCTIONALITY

TPS2550

TPS2551

SLVS736 – FEBRUARY 2008

Some applications require that an overcurrent condition disables the part momentarily during a fault condition

and re-enables after a pre-set time. This auto-retry functionality can be implemented with an external resistor and

capacitor. During a fault condition, FAULT pulls low disabling the part. The part is disabled when EN is pulled

on EN reaches the turnon threshold, and the auto-retry time is determined by the resistor/capacitor time

constant. The part will continue to cycle in this manner until the fault condition is removed.

Figure 22. Auto-Retry Functionality

Some applications require auto-retry functionality and the ability to enable/disable with an external logic signal.

functionality. The resistor/capacitor time constant determines the auto-retry time-out period.

Figure 23. Auto-Retry Functionality With External EN Signal

The circuit in Figure 24 uses an SN74HC00 quad-NAND gate to implement overcurrent latch-off. The SN74HC00

high-speed CMOS logic gate is selected because it operates over the 2.5V – 6.5V range of the TPS2550/51.

is stable to ensure that the switch initializes in the OFF state. A logic high on ENABLE turns on the switch after

disables the switch. The host can monitor STAT for an overcurrent condition. Toggling ENABLE resets STAT and

re-enables the switch.

Copyright © 2008, Texas Instruments Incorporated

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Product Folder Link(s): TPS2550 TPS2551