4

PS12

Pin #

Function

Description

15

VIN

Power supply pins.

VIN positive with respect to VEE.

The outputs PSA thru PSD are pulled to a logic low state upon application of power.

1

VEE

2PUD

Hookup pin for the power-up-delay (PUD) timing capacitor.

Pin pulls capacitor to ground upon application of power. (See timing diagram)

3

ON

Input pin of the ON comparator. Rising transition initiates power-up sequence.

4

OV

Input pin of the OV comparator. Rising transition initiates the power-down sequence.

5TAB

Hookup pins for timing resistors.

On power-up, the resistor at TAB determines the delay between the rising transitions of PSA and

PSB; similarly, TBC relates to ( PSB / PSC ), and TCD to ( PSC / PSD ).

On power-down, the resistor at TDC determines the delay between the falling transitions of PSD

and PSC; similarly, TCB relates to ( PSC / PSB ), and TBA to ( PSB / PSA ).

6TBC

7TCD

8

TDC

9TCB

10

TBA

11

PSA

Power supply enable output pins.

These four pins control loads, such as DC/DC converter modules, load switches, ICs, etc.

Configured with open drain output stages.

On power-up, right after expiration of the PUD delay, the sequencer asserts PSA, and subsequently

asserts PSB, PSC and PSD observing the delays, programmed by the (TAB, TBC, and TCD)

pins.

On power-down, the sequencer deasserts PSD, and subsequently deasserts PSC, PSB, and PSA

observing the delays, programmed by the (TAB, TBC, and TCD) pins.

12

PSB

13

PSC

14

PSD

16

NC

No connect

Pin Description