LP3913 Datasheet, PDF (55/70 Pages) Texas Instruments – Power Management IC for Flash Memory-Based Portable Media Players

LP3913
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BUCK2 Control Register (06)h
Access
Data
D7
D6
D5
Read Only R/W
0
Reserved Operation Force PWM mode
0: disabled 0: Automatic Modulation Mode
1: enabled 1: Force PWM mode
Reset
n/a
1
0
SNVS489I – NOVEMBER 2006 – REVISED SEPTEMBER 2013
D4–0
5’h1F
BUCK2 Output Voltage (V)
5’h00
Externally controlled
5’h01
1.80
5’h02
1.90
5’h03
2.00
5’h04
2.10
5’h05
2.20
5’h06
2.30
5’h07
2.40
5’h08
2.50
5’h09
2.60
5’h0A
2.70
5’h0B
2.80
5’h0C
2.90
5’h0D
3.00
5’h0E
3.10
5’h0F
3.20
5’h1x
3.30
BUCK3: Synchronous Magnetic DC/DC Converter
The LP3913 is equipped with a synchronous Buck3 magnetic DC-DC converter to supply power to the Flash
memory that has a typical 1.7V-3.3V operating voltage. This voltage is lower than the maximum battery voltage
(4.2V typically for Li-polymer cells) and higher than the minimum battery voltage (typically 2.8V). Therefore, in
order to provide 3.3V, regardless of the battery voltage, the Buck3 converter efficiently steps down the battery
voltage. The Buck3 automatically switches between PWM and PFM modes depending on the load.
By setting bit D6 of the Buck3 control register, the Buck3 will be forced to operate using PWM modulation
regardless of the load. By default, this bit is cleared.
Figure 68. Schematic Section for Buck3 Operation
35
VBUCK3L1
BUCK3
Lsw3
2.2 2H
33
VBUCK3L2
32
VBUCK3
VFB3
31
Csw3
22 2F
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