LTC3108

7

3108p

BLOCK DIAGRAM

OPERATION

The LTC3108 is designed to use a small external step-up

transformer to create an ultralow input voltage step-up

DC/DC converter and power manager. It is ideally suited

for low power wireless sensors and other applications in

which surplus energy harvesting is used to generate system

power because traditional battery power is inconvenient

or impractical.

The LTC3108 is designed to manage the charging and

regulation of multiple outputs in a system in which the

average power draw is very low, but there may be periodic

pulses of higher load current required. This is typical of

wireless sensor applications, where the quiescent power

draw is extremely low most of the time, except for transmit

bursts when circuitry is powered up to make measure-

ments and transmit data.

The LTC3108 can also be used to trickle charge a standard

capacitor, supercapacitor or rechargeable battery, using

energy harvested from a Peltier or photovoltaic cell.

(Refer to the Block Diagram)

3108 BD

C1

C2

5M

SW

5.25V

1.2V

SW

VHOLD

VLDO

OFF ON

PROGRAM

PGOOD

VS1

VS2

PGD

VSTORE

C1

VLDO

1μF

1:100

C2

SYNC RECTIFY

REFERENCE

2.2V

CHARGE

CONTROL

VAUX

+

–

+

–

ILIM

LTC3108

1.3Ω

0.5Ω

1M

EXPOSED PAD (DFN)

2.2μF

GND (SSOP)

LDO

(DFN Package Shown)