Datasheet

LTC2924
14
2924fb
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 (FAULT 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 FAULT pin is immediately
pulled low indicating the fault condition.
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 FAULT
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 FAULT
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
V
CC
. This internal/external fault indicator can be especially
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
applicaTions inForMaTion
IN1
IN2
IN3
IN4
OUT1
OUT2
OUT3
OUT4
LTC2924
2924 F09
PS2
PS1