UCD9090
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SLVSA30A –APRIL 2011–REVISED AUGUST 2011
Figure 8. Fusion GUI Flash-Error Log (Logged Faults)
POWER-SUPPLY SEQUENCING
The UCD9090 can control the turn-on and turn-off sequencing of up to 10 voltage rails by using a GPIO to set a
power-supply enable pin high or low. In PMBus-based designs, the system PMBus master can initiate a
sequence-on event by asserting the PMBUS_CNTRL pin or by sending the OPERATION command over the I2C
serial bus. In pin-based designs, the PMBUS_CNTRL pin can also be used to sequence-on and sequence-off.
The auto-enable setting ignores the OPERATION command and the PMBUS_CNTRL pin. Sequence-on is
started at power up after any dependencies and time delays are met for each rail. A rail is considered to be on or
within regulation when the measured voltage for that rail crosses the power-good on (POWER_GOOD_ON(1))
(1) In this document, configuration parameters such as Power Good On are referred to using Fusion GUI names. The UCD90xxx
Sequencer and System Health Controller PMBus Command Reference name is shown in parentheses (POWER_GOOD_ON) the first
time the parameter appears.
Copyright © 2011, Texas Instruments Incorporated
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