Datasheet

VOUT_MARGIN_HIGH
VOUT_CAL_OFFSET
VOUT_MARGIN_LOW
VOUT_COMMAND
+
Limiter
3:1
Mux
VOUT_
SCALE_
LOOP
Vref DAC
digital
compensator
eADC
+
V
Sense
VOUT_OV_FAULT_LIMIT
VOUT_OV_WARN_LIMIT
VOUT_UV_WARN_LIMIT
VOUT_UV_FAULT_LIMIT
R1
R2
V
OUT
VOUT_MAX
3:1
Mux
VID_CODE_RAILx
OPERATION Command
4-wire VID interface
VID_CONFIG
UCD9222
SLVSAL7A –NOVEMBER 2010– REVISED FEBRUARY 2011 www.ti.com
ON_OFF_CONFIG
The ON_OFF_CONFIG command is used to select the method of turning rails on and off. It can be configured so
that the rail:
• stays off,
• turns on automatically,
• responds to the PMBus_Cntrl pin,
• responds to OPERATION command, or
• responds to logical-AND of the PMBus_Cntrl pin and the OPERATION command.
The ON_OFF_CONFIG command also sets the active polarity of the PMBus_Cntrl pin.
EN1/EN2
In addition to the PMBus_Cntrl pin supported by all UCD92xx products, the UCD9222 also supports separate
Enable pins for each rail. The polarity of the EN1/EN2 pin is user-configurable, and will be the same as the
polarity chosen for the PMBus_Cntrl pin by the ON_OFF_CONFIG command. When the ON_OFF_CONFIG
setting is configured to respond the PMBus_Cntrl pin, the PMBus_Cntrl pin signal will be logically ANDed with
the rail’s EN pin signal.
PG1/PG2
In addition to the PowerGood output signal supported by all UCD92xx products, the UCD9222 also supports
separate PG indicators for each rail. The PowerGood signal is the logical-AND of all rails, while PG1 and PG2
indicate the status of a single rail. All three of these indicators are open-drain outputs, so they require pull-up
resistors. When driving external circuits with logic voltages less than 3.3V, the pull-ups may be tied to that lower
supply voltage, thus avoiding the need for level-shifters.
Output Voltage Adjustment
The output voltage may be set to maintain a steady voltage or it may be controlled dynamically by the VID
interface, depending on the VID_CONFIG setting. When not being commanded by the VID interface, the nominal
output voltage is programmed by a combination of PMBus settings: VOUT_COMMAND, VOUT_CAL_OFFSET,
VOUT_SCALE_LOOP, and VOUT_MAX. Their relationship is shown in Figure 10. These PMBus parameters
need to be set such that the resulting Vref DAC value does not exceed the maximum value of V
ref
.
Output voltage margining is configured by the VOUT_MARGIN_HIGH and VOUT_MARGIN_LOW commands.
The OPERATION command selects between the nominal output voltage and either of the margin voltages. The
OPERATION command also includes an option to suppress certain voltage faults and warnings while operating
at the margin settings.
Figure 10. PMBus Voltage Adjustment Mechanisms
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