LT3487

1

3487f

Boost and Inverting

Switching Regulator

for CCD Bias

Li-Ion Cell

Before Negative Channel Begins Switching

Output Voltages

Power and Control Circuitry

× 3mm) DFN Package

APPLICATIO S

FEATURES

DESCRIPTIO

TYPICAL APPLICATIO

positive and negative outputs for biasing CCD imagers.

The device delivers up to –8V at 90mA and 15V at 45mA

from a lithium-ion cell, providing bias for many popular

CCD imagers. The boost regulator incorporates output

disconnect technology to eliminate the DC current path

boost configurations. The 2MHz switching frequency

allows CCD solutions using 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

the external component count.

Intelligent soft-start allows sequential soft-start of the two

channels with a single capacitor. The soft-start is sequenced

such that the output ramp of the negative channel begins

after the ramp of the positive channel. Internal sequencing

circuitry also disables the negative channel until the positive

channel has reached 87% of its final value, ensuring that

the sum of the two outputs is always positive.

The LT3487 is available in a 10-pin 3mm

× 3mm DFN

package.

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

All other trademarks are the property of their respective owners.

SWN

15

µH10µH

CAP

549k

FBP

LT3487

GND

SWP

DN

15

µH

324k

47pF

FBN

RUN/SS

RUN/SS

–8V

90mA

100nF

4.7

µF

3487 TA01a

100nF

15V

45mA

1

µF

2.2

µF

22

µF

3V TO 12V

Conversion Efficiency

LOAD CURRENT (mA)

0

55

60

65

60

100

3487 TA01b

50

45

40

20

40

80

70

75

80

POS CHANNEL AT CAP

NEG CHANNEL

POS CHANNEL