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LT3472EDD

Boost and Inverting DC/DC Converter for CCD Bias

Linear Technology 

FEATURES

■ Generates 15V at 20mA, –8V at 50mA

from a Li-Ion Cell

■ Internal Schottky Diodes

■ VIN 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

U

APPLICATIO S

■ CCD Bias

■ TFT LCD Bias

■ OLED Bias

■ ± Rail Generation for Op Amps

, LTC and LT are registered trademarks of Linear Technology Corporation.

TYPICAL APPLICATIO

LT3472

Boost and Inverting

DC/DC Converter

for CCD Bias

DESCRIPTIO

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

50mm2.

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.

Li-Ion CCD Bias Supply

VIN

3V TO 4.2V

22µH

47µH

2.2µF

1µF

VPOS

15V

20mA

550k

4.7pF

SWP

VPOS

FBP

VIN

LT3472

SHDN

2.2µF

SHDN

SSP

GND

100nF

SWN

DN

FBN

320k

10pF

47µH

VNEG

–8V

50mA

SSN

100nF

2.2µF

3472 TA01a

Conversion Efficiency

85

80

POS CHANNEL

75

70

NEG CHANNEL

65

60

55

50

45

40

0

10

20

30

40

50

LOAD CURRENT (mA)

3472 TA01b

3472f

1

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