ISL97642

FN6436 Rev 0.00

Page 16 of 19

June 18, 2007

Component Selection for Start-up Sequencing and

Fault Protection

1µF and should not be more than five times the capacitor on

from 22nF minimum to several microfarads – only limited by the

use of a larger/smaller value will vary this time proportionally

(e.g. 1µF will give a fault time-out period of typically 230ms).

Fault Sequencing

The ISL97642 has an advanced fault detection system, which

protects the IC from both adjacent pin shorts during operation

and shorts on the output supplies. A high quality layout/design

of the PCB (in respect of grounding quality and decoupling) is

necessary to avoid falsely triggering the fault detection scheme

– especially during start-up. The user is directed to the layout

IN

NORMAL

OPERATION

FAULT

PRESENT

START-UP SEQUENCE

FIGURE 22. START-UP SEQUENCE

NOTE: Not to scale