UCC2913

UCC3913

SLUS274A – JANUARY 1999 – REVISED APRIL 2003

4

www.ti.com

TERMINAL FUNCTIONS

TERMINAL

I/O

DESCRIPTION

NAME

NO.

I/O

DESCRIPTION

CT

4

I

A capacitor is connected to this pin in order to set the maximum fault time.

IMAX

2

I

This pin programs the maximum allowable sourcing current.

OUT

7

O

Output drive to the MOSFET pass element.

PL

8

I

This feature ensures that the average MOSFET power dissipation is controlled.

SENSE

6

I

Input voltage from the current sense resistor.

SD/FLT

1

O

This pin provides fault output indication and shutdown control.

VDD

3

O

Current driven with a resistor to a voltage at least 10V more positive than VSS.

VSS

5

O

Ground reference for the device and the most negative voltage available.

DETAILED PIN DESCRIPTIONS

CT

A capacitor connected to this pin allows setting of the maximum fault time. The maximum fault time must be

more than the time to charge external load capacitance. The maximum fault time is defined as:

t

2

C

T

I

CH

where

I

given by:

t

C

T

IMAX

appears as a current source is equal to the voltage on the IMAX pin over the current sense resistor. If desired,

a controlled current startup can be programmed with a capacitor on the IMAX pin, and a programmed start delay

can be achieved by driving the shutdown with an open collector/drain device into an R-C network.

PL

This pin’s feature ensures that the average MOSFET power dissipation is controlled. A resistor is connected

from this pin to the drain of the N-channel MOSFET pass element. When the voltage across the N-channel

MOSFET exceeds 5 V, current flows into the PL pin which adds to the fault timer charge current, reducing the

is given by:

P

1

R

PL

SENSE

Input voltage from the current sense resistor. When there is greater than 50 mV across this pin with respect to

(1)

(2)

(3)

(4)