Datasheet
LT3472
1
3472f
TYPICAL APPLICATIO
U
APPLICATIO S
U
FEATURES
DESCRIPTIO
U
■
CCD Bias
■
TFT LCD Bias
■
OLED Bias
■
± Rail Generation for Op Amps
■
Generates 15V at 20mA, –8V at 50mA
from a Li-Ion Cell
■
Internal Schottky Diodes
■
V
IN
Range: 2.2V to 16V
■
Output Voltages Up to ±34V
■
Capacitor-Programmable Soft-Start
■
Sequencing: Positive Output Reaches 88% of Final
Value Before Negative Output Begins
■
Requires Only One Resistor to Set Output Voltage
■
Constant Switching Frequency Ensures Low
Noise Outputs
■
Available in a 10-Lead (3mm × 3mm) DFN Package
Boost and Inverting
DC/DC Converter
for CCD Bias
The LT
®
3472 dual channel switching regulator generates
positive and negative outputs for biasing CCD imagers.
The device delivers up to –8V at 50mA and 15V at 20mA
from a lithium-ion cell, providing bias for many popular
CCD imagers. Switching at 1.1MHz, the LT3472 uses tiny,
low profile capacitors and inductors and generates low
noise outputs that are easy to filter. Schottky diodes are
internal and the output voltages are set with one resistor
per channel, reducing external component count. The
entire solution is less than 1mm profile and occupies just
50mm
2
.
Internal sequencing circuitry disables the negative chan-
nel until the positive channel has reached 88% of its final
value, ensuring that the sum of the two outputs is always
positive. Separate soft-start capacitors for each output
allow the ramp of each output to be independently
controlled.
The LT3472 is available in a low profile (0.75mm) 10-pin
3mm × 3mm DFN package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
SWP V
IN
SWN
SSP GND SSN
V
POS
FBP
SHDN
FBN
DN
LT3472
2.2µF
2.2µF
2.2µF
100nF
47µH
100nF
550k
320k
1µF
22µH47µH
SHDN
V
IN
3V TO 4.2V
V
POS
15V
20mA
V
NEG
–8V
50mA
3472 TA01a
4.7pF
10pF
Conversion Efficiency
LOAD CURRENT (mA)
0
EFFICIENCY (%)
20
40
50
85
80
75
70
65
60
55
50
45
40
3472 TA01b
10 30
POS CHANNEL
NEG CHANNEL
Li-Ion CCD Bias Supply