Specification Sheet

Datasheet, Volume 1 of 2 39
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Electrical Specifications
Power source characteristics must be guaranteed to be stable whenever the supply to
the voltage regulator is stable.
5.2.8.5 SetWP Working Point Command
The SetWP is a command that invokes a look up table for VID set points. During the
initial power on phase the CPU will program the WPx registers (WP0=3Ah..WP7=41h)
on a per rail address basis. When use with the AllCall address, SetWP acts as a group
command that moves all voltage rails on the bus to new voltages in the look up table
index. The SetWP command can also be used with an individual VR rail address and
that rail moves to the voltage in the loop up table index. Each VR domain address has
registers WP0-WPx (3Ah..41h) which stores the VID code for that domain's work
points.
The Work Point command is encoded to support up to 8 VID targets, slew rate for the
command, and alert function. The PWM should use its auto power state or auto-phase
shedding functions to select appropriate # phases, CCM/DCM operation, and so forth.
based on output load current after the SetWP command target has been reached.
Typical SetWP usage will be:
1. Processor writes VID codes to WP registers WP0 (3Ah) -WP4 (3Dh) in each VR
domain. Normally done during SVID enumeration phase of system boot.
2. If a WP0-7 register is not programmed by the CPU, the VR stays at its present VID
setting when it receives a SetWP (WPn) command.
3. Processor sends SetWP (WPn) command to one of the AllCall addresses 0Eh or 0Fh.
See PWM guideline for more information on AllCall address mapping.
4. Voltage rails change VID to their corresponding VID code stored in their WPx
register
5. CPU polls each VR addresses reading stutus1 to clear the alerts from the VRs
6. SVID error handling
WP0 = State 0, programed by master
WP1 = State 1, programmed by master
WP2 = State 2, programmed by master
WP3 = State 3, programmed by master
WP4 = State 4, programmed by master
…
WP7 = State 7
5.2.8.6 SetVID Fast Command
The SetVID_Fast command contains the target VID in the payload byte. The range of
voltage is defined in the VID table. The VR should ramp to the new VID setting with a
fast slew rate as defined in the slew rate data register. It is minimum of 25 mV/µs for
V
CCIN and 10 mV/µs for other rails, depending on the amount of decoupling
capacitance.