34704_09 Datasheet, PDF (30/49 Pages) Freescale Semiconductor, Inc – Multiple Channel DC-DC Power Management IC

FUNCTIONAL DEVICE OPERATION
LOGIC COMMANDS AND REGISTERS
LOGIC COMMANDS AND REGISTERS
I²C USER INTERFACE
The 34704 communicates via I²C using a default device
address $54 to access all user registers and program all
regulators features independently.
USER PROGRAMMABLE REGISTERS
GrpC/E power sequencing setting (34704A Only)
The microprocessor can choose one of several voltage
sequence options for the GrpC/E supply (REG5), high
voltage supply (REG6), and negative voltage supply (REG7).
For 3 of the sequencing options, REG5 supply is controlled
and tied with REG6 and REG7 in a preset power sequence.
For one sequencing option, only REG6 and REG7 are
involved in the power sequence and REG5 is independent.
34704A assigns a 2-bit register to program the GrpC/E
power sequencing options (CCDSEQ Register). This register
value is latched in at GrpC power up and will not be allowed
to change unless a power recycle happens.
OPTION MSB LSB
1
0
0
(Default)
2
0
1
3
1
0
4
1
1
GRPC/E ENABLED
REG5 is independently controlled
REG6 and REG7 ramp up together.
REG5 ramps up first
Then REG6 and REG7 ramp up together
REG5, REG6, and REG7 ramp up together
REG5 and REG6 ramp up together first.
Then ramp up REG7
GRPC/E DISABLED
REG5 is independently controlled
REG6 and REG7 ramp down together
REG5, REG6 and REG7 ramp down together
REG5, REG6, and REG7 ramp down together
REG7 ramps down first.
Then REG5 and REG6 ramp down together
Switching frequency for REG6, 7 & 8
F_SW2 can be selected to be between 250kHz and 1.0MHz
in 250kHz steps. On the 34704B, FSW2 is just for REG8
since REG6 and 7 do not exist in this device.
34704 assigns a 2-bit register to program F_SW2 (F_SW2
Register)
FSW2
500kHz (Default)
250kHz
750kHz
1000kHz
MSB LSB
0
0
0
1
1
0
1
1
Shutdown Hold (Delay) Time
The 34704 assigns a 2-bit register (SDDELAY Register)
for the processor to program the shutdown delay time period
Shutdown Delay
1.0sec (Default)
0.5sec
1.5sec
2.0sec
MSB LSB
0
0
0
1
1
0
1
1
Please refer to the /ONOFF pin description for more
details
Programming 34704 response to under-voltage/over-
voltage conditions on each regulator
There are two responses that can be programmed for an
over-voltage/under-voltage condition:
Response A: When an over-voltage (under-voltage) event
is detected, the concerned output shuts down and a register
is flagged to alert the processor.
Response B: When an over-voltage/under-voltage event
is detected, the concerned output will not shutdown, but the
register is flagged to alert the processor. Then, the processor
can decide whether to shutdown the output or not. In the
mean time, the concerned output control loop will be
attempting to correct the error.
See Output Over-voltage/Under-voltage Monitoring on
page 29 for more details.
Response A and Response B share the same flag register
34704 assigns a 1-bit register for this function
(OVUVSETx Register) where x corresponds to each
regulator
34704
30
Analog Integrated Circuit Device Data
Freescale Semiconductor