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PXA300 Processor and PXA310 Processor
Vol. I: System and Timer Configuration Developers Manual
Doc. No. MV-TBD-00 Rev. A
CONFIDENTIAL
Copyright © 12/13/06 Marvell
Page 214
Document Classification: Proprietary Information
December 13, 2006
Not approved by Document Control. For review only.
The dedicated I
2
C module used by the voltage manager is nearly identical to the I
2
C described in “I
2
C Bus
Interface Unit” chapter. The PWR_I
2
C is located within the services unit and is optimized and dedicated for
connection to the external voltage regulator only.
8.8.1
Programming Restrictions for the PWR_I
2
C
The PWR_I
2
C is a full-function I
2
C-capable of all normal operations, including master and slave, receive and
transmit operation, but is dedicated to power-management-initiated transfers. The PWR_I
2
C cannot be used as a
general-purpose I
2
C interface. PWR_I
2
C supports fast-mode operation of up to 400 Kbps. When used with the
voltage-change sequencer, PWR_I
2
C operates in fast-mode. The PWR_I
2
C is always enabled, because it is used
during the SOD sequence.
The voltage-change sequencer sends commands under hardware control during SOD, application core frequency
changes, power-mode changes, and changes due to high temperature. When the PWR_I
2
C is sending commands,
the VCSA bit in the
“Power Management Unit Voltage Change Control Register (PVCR)”
is set and the
PWR_I
2
C registers are not writable and read unknown values. Software checks the VCSA bit before reading or
writing the PWR_I
2
C and reads registers following a write to ensure that the read occurred. When the
voltage-change sequencer is operating, writes to PVCR result in unpredictable operation.
8.8.2
External Voltage Regulator Requirements
Preserving functionality during any voltage change requires a special external voltage regulator. The regulator
must have these features to be compatible with all voltage management features:
•
Implement required registers as specified in the PXA300 processor PMIC application note.
•
Programmable buck converters output to drive VCC_APPS and VCC_SRAM with 32 output levels between
the voltages 0.725–1.50 V.
•
I
2
C controlled voltage level selection and voltage enable control.
•
Limited overshoot and undershoot during voltage change.
8.8.3
Hardware-Controlled Voltage-Change Sequencer
The voltage manager contains a voltage-change sequencer, which automatically sends hard-coded command
sequences to the external regulator when triggered by the following events:
•
SOD
•
Application-subsystem frequency and application core frequency and turbo change
•
PMU power-mode changes, including MPMU S-state change and BPMU D-state changes
•
On-chip temperature exceeding 100
o
C
•
S3 entry due to nBATT_FAULT asserted with PCMR[BIE] = 0
The sequencer can send hard-coded commands to enable the VCC_APPS and VCC_SRAM
supplies and control
the output voltage and voltage ramping of VCC_APPS and VCC_SRAM. The hardware-controlled sequencer
can be disabled using the FVE, PVE, and TVE bits in the
“Power Management Unit Voltage Change Control
.