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
UCD9244
www.ti.com SLVSAL6A –NOVEMBER 2010–REVISED FEBRUARY 2011
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.
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
For a complete description of the commands supported by the UCD9244 see the UCD92xx PMBUS Command
Reference (SLUU337). Each of these commands can also be issued from the Texas Instruments Fusion Digital
Power™ Designer program. This Graphical User Interface (GUI) PC program issues the appropriate commands
to configure the UCD9244 device.
Calibration
To optimize the operation of the UCD9244, PMBus commands are supplied to enable fine calibration of output
voltage, output current, and temperature measurements. The supported commands and related calibration
formulas may be found in the UCD92xx PMBUS Command Reference (SLUU337).
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