MC34704 FREESCALE [Freescale Semiconductor, Inc], MC34704 Datasheet - Page 30

• Manufacturer Part Number: MC34704
• Description: Multiple Channel DC-DC Power Management IC
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

I
address $54 to access all user registers and program all
regulators features independently.
USER PROGRAMMABLE REGISTERS
GrpC/E power sequencing setting (34704A Only)
sequence options for the GrpC/E supply (REG5), high
Switching frequency for REG6, 7 & 8
in 250kHz steps. On the 34704B, FSW2 is just for REG8
since REG6 and 7 do not exist in this device.
Register)
Shutdown Hold (Delay) Time
for the processor to program the shutdown delay time period
30
34704
FUNCTIONAL DEVICE OPERATION
LOGIC COMMANDS AND REGISTERS
2
C USER INTERFACE
OPTION
(Default)
The 34704 communicates via I
The microprocessor can choose one of several voltage
F
34704 assigns a 2-bit register to program F
The 34704 assigns a 2-bit register (SDDELAY Register)
SW2
1
2
3
4
can be selected to be between 250kHz and 1.0MHz
500kHz (Default)
Shutdown Delay
1.0sec (Default)
MSB
1000kHz
0
0
1
1
250kHz
750kHz
FSW2
0.5sec
1.5sec
2.0sec
LSB
0
1
0
1
REG5, REG6, and REG7 ramp up together
2
Then REG6 and REG7 ramp up together
C using a default device
REG5 and REG6 ramp up together first.
MSB
MSB
REG6 and REG7 ramp up together.
REG5 is independently controlled
0
0
1
1
0
0
1
1
LOGIC COMMANDS AND REGISTERS
Then ramp up REG7
GRPC/E ENABLED
REG5 ramps up first
SW2
LSB
LSB
0
1
0
1
0
1
0
1
(F
SW2
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.
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.
details
Programming 34704 response to under-voltage/over-
voltage conditions on each regulator
over-voltage/under-voltage condition:
is detected, the concerned output shuts down and a register
is flagged to alert the processor.
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.
page 29
(OVUVSETx Register) where x corresponds to each
regulator
34704A assigns a 2-bit register to program the GrpC/E
Please refer to the /ONOFF pin description for more
There are two responses that can be programmed for an
Response A: When an over-voltage (under-voltage) event
Response B: When an over-voltage/under-voltage event
See Output Over-voltage/Under-voltage Monitoring on
Response A and Response B share the same flag register
34704 assigns a 1-bit register for this function
for more details.
REG5, REG6, and REG7 ramp down together
REG5, REG6 and REG7 ramp down together
Then REG5 and REG6 ramp down together
REG6 and REG7 ramp down together
REG5 is independently controlled
Analog Integrated Circuit Device Data
REG7 ramps down first.
GRPC/E DISABLED
Freescale Semiconductor