SLVSC86A January 2014 – March 2014 UCD9244-EP
PRODUCTION DATA.
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 7. These PMBus parameters need to be set such that the resulting Vref DAC value does not exceed the maximum value of Vref.
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.
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.