PIN FUNCTIONS

N

°

Name

Function

1

N.C.

Must not be connected. Leave open circuit.

2

Output

Regulator Output.

3

Supply Voltage

Unregulated Voltage Input. An internal regulator powers the L4964’s internal logic.

4

N.C.

Must not be connected. Leave open circuit.

5

Soft Start

Soft Start Time Constant. A capacitor is connected between this terminal and ground

to define the soft start time constant. This capacitor also determines the average short

circuit output current.

6

Inhibit Input

TTL - Level Remote Inhibit. A logic high level on this input disables the L4964.

7

Sync Input

Multiple L4964’s are synchronized by connecting the pin 7 inputs together and omitting

the oscillator RC network on all but one device.

8

Ground

Common Ground Terminal.

9

Frequency

Compensation

A series RC network connected between this terminal and ground determines the

regulation loop gain characteristics.

10

Feedback

Input

The Feedback Terminal of the Regulation Loop. The output is connected directly to

this terminal for 5.1 V operation ; it is connected via a divider for higher voltages.

11

Oscillator

A parallel RC network connected to this terminal determines the switching frequency.

The pin must be connected to pin 7 input when the internal oscillator is used.

12

Reset Input

Input of the Reset Circuit. The threshold is roughly 5 V. It may be connected to the

beedback point or via a divider to the input.

13

Reset Delay

A capacitor connected between this terminal and ground determines the reset signal

delay time.

14

Reset Output

Open Collector Reset Signal Output. This output is high when the supply is safe.

15

N.C.

Must not be connected. Leave open circuit.

BLOCK DIAGRAM

L4964

2/13