LTC2924

13

2924fa

Connecting Unused OUT and IN Pins

Figure 9 shows how to connect unused OUT and IN pins

on the LTC2924. Unused OUT-IN pairs must be connected

together to ensure proper operation.

Fault Detection

The LTC2924 has sophisticated fault detection which can

detect:

• Power On and Power Off sequence errors

• System controller command errors

• Power On timeout failure (with the power good timer

enabled)

• Externally commanded faults (FAULT pin pulled low)

If any of the above faults are detected, the LTC2924

immediately pulls the OUT1-OUT4 pins low turning off

all of the power supplies. If the fault condition is detected

in one of the supplies controlled by the LTC2924 (an “in-

ternally generated” fault), the FAULT pin is immediately

pulled low indicating the fault condition.

APPLICATIO S I FOR ATIO

Clearing the Fault Condition

In order to clear the fault condition within the LTC2924,

the following conditions must exist:

• All four IN pins must be below 0.61V

• The ON pin must be below 0.61V

• In the case of an externally generated fault, the



FAULT pin must not be pulled down.

Fault Condition Indicator

If the LTC2924 receives a commanded fault (a cascaded

LTC2924 or an external source pulls down on the FAULT

pin) the LTC2924 will pull the TMR pin low. If the LTC2924

has detected the fault itself (from its internal fault detec-

tion circuits) it will indicate so by raising the TMR pin to

helpful while searching for the source of a fault condition

when multiple LTC2924s are cascaded.

If a fault occurs when the ON pin is high, the fault status

indication on the TMR pin will remain valid until the ON

pin goes low.

Figure 9. Connecting Unused OUT and IN Pins

IN1

IN2

IN3

IN4

OUT1

OUT2

OUT3

OUT4

LTC2924

2924 F09

PS2

PS1