Datasheet

Data Sheet ADM1186
Rev. B | Page 17 of 28
AUTOMATIC STARTUP AND AUTOMATIC RETRY
USING A SUPPLY RAIL
It is not possible to directly connect the V
CC
supply to the UP
pin (ADM1186-1) or to the UP/
DOWN
pin (ADM1186-2) to
start a sequence as the V
CC
comes up. When the UVLO circuit
enables the state machine, it begins in the fault handler states.
To reach the WAIT START state so that sequencing can begin,
the UP pin (ADM1186-1) or the UP/
DOWN
pin (ADM1186-2)
must be held low after the state machine is enabled. The circuit
shown in
Figure 28 can be used to make the ADM1186-1
automatically start and automatically retry in the event of fault.
R2
100kΩ
100kΩ
C
DELA
Y
07153-128
R1
5V
5V
5V
DOWN
UP
ADM1186-1
STATE
MACHINE
1.4V
FAULT
OUT1
R
H
Figure 28. Configuration for Automatic Startup and Retry after Fault
When a fault occurs and the fault hold time elapses, the state
machine enters the CLEAR FAULT state. The ADM1186-1
remains in this state until a low voltage is applied at the UP pin.
The low voltage at the
FAULT
pin causes the voltage at the node
of the UP and
DOWN
pin connection to fall. This allows the
state machine to advance from the CLEAR FAULT state, in
readiness for a new power-up sequence. The
FAULT
pin is then
asserted high followed by the UP pin after a delay set by C
DELAY
.