34704_09 Datasheet, PDF (32/49 Pages) Freescale Semiconductor, Inc – Multiple Channel DC-DC Power Management IC

FUNCTIONAL DEVICE OPERATION
LOGIC COMMANDS AND REGISTERS
Soft Start
0.5ms
2ms
8ms
32ms
MSB LSB
0
0
0
1
1
0
1
1
REG8 Regulation Mode
The 34704 assigns a 1-bit register to indicate REG8’s
regulation mode (REG8MODE Register). The processor
assigns this register to either regulation mode before
enabling the REG8 output.
REG8 Regulation
bit
Current (Default)
0
Voltage
1
When REG8 is current regulated, LED backlight current
can be reduced from the maximum in 16 steps through
the I²C interface
The maximum LED current can be set using the external
resistor at the bottom of the LED string, then through I²C
programming, this current value can be reduced in 16 steps.
34704 assigns a 4-bit register for this function (ILED
register)
The ILED setting is not a guaranteed characteristic from
I_MAX* (1/16) to I_MAX* (9/16), due to an error amp common
mode limitation.
LED Current
IMAX * (1/16)
IMAX * (2/16)
IMAX * (3/16)
IMAX * (4/16)
IMAX * (5/16)
IMAX * (6/16)
IMAX * (7/16)
IMAX * (8/16)
IMAX * (9/16)
IMAX * (10/16)
IMAX * (11/16)
IMAX * (12/16)
IMAX * (13/16)
IMAX * (14/16)
IMAX * (15/16)
IMAX (Default)
MSB
0
0
0
0
0
0
0
0
0
1
0
1
0
1
0
1
1
0
1
0
1
0
1
0
1
1
1
1
1
1
1
1
LSB
0
0
0
1
1
0
1
1
0
0
0
1
1
0
1
1
0
0
0
1
1
0
1
1
0
0
0
1
1
0
1
1
USER ACCESSIBLE FLAG REGISTERS
Cold Start Flag
The 34704 assigns a 1-bit register (COLDF Register) to
flag the processor that the power up was a result of battery
insertion and not through ONOFF pin. This flag should be
cleared after power up by the processor.
Cold Start Flag
bit
/ONOFF (Default)
0
Battery Insertion
1
Shutdown Flag
The 34704 assigns a 1-bit register (SHUTDOWN Register)
to flag the processor if a shutdown signal is received through
the ONOFF pin and a programmable time period with a
default of 1sec has elapsed.
/ONOFF Status
bit
Normal (Default)
0
Shutdown
1
Dynamic Voltage Scaling Status Flag
In addition and for each regulator, 34704 assigns a 1-bit
register (DVSSTATx register) to flag to the processor that the
desired output voltage level set with the (DVSSETx register)
has been reached.
DVS STATUS
bit
DVS Not Done
0
DVS Done
1
USER ACCESSIBLE FAULT REGISTERS
Over-current Fault Register
The 34704 assigns a 1-bit register for each regulator
(ILIMFx Register) to indicate a fault due to over-current limit,
where x corresponds to each regulator from REG1 to REG8,
except REG7
ILIMF
bit
False
0
True
1
Short-circuit Fault Register
The 34704 assigns a 1-bit register for each regulator
(SCFx Register) to indicate a fault due to short-circuit current
limit, where x corresponds to each regulator from REG1 to
REG8, except REG7
34704
32
Analog Integrated Circuit Device Data
Freescale Semiconductor