LTC3537

1

3537fa

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

2.2 MHz, 600mA

Synchronous Step-Up DC/DC

Converter and 100mA LDO

DC/DC converter with an idependent 100mA low dropout

regulator (LDO). The step-up converter starts from an input

voltage as low as 0.68V and contains an internal 0.4

Ω

switch and a 0.6

Ω synchronous rectifier that disconnects

from the output when disabled in shutdown.

A switching frequency of 2.2MHz minimizes solution

footprint by allowing the use of tiny, low profile inductors

and ceramic capacitors. The current mode PWM design

is internally compensated, reducing external parts count.

Fixed frequency switching is maintained until a light load

engaged to maximize efficiency. For low noise operation,

Burst Mode Operation can be disabled. Anti-ring circuitry

reduces EMI by damping the inductor in discontinuous

mode. Additional features include a low shutdown current

of under 1μA and thermal overload protection.

The integrated LDO regulator provides a very low noise,

programmable low dropout supply.

Step-Up

Linear LDO Regulator

Combined

× 3mm × 0.75mm Package

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

All other trademarks are the property of their respective owners.

Efficiency and Power Loss

vs Load Current

LOAD CURRENT (mA)

0.01

100

80

90

60

20

30

40

70

50

10

0

1000

10

0.1

1

100

0.01

10

0.1

3537 TA01b

1000

1100

EFFICIENCY

POWER LOSS

3537 TA01a

LTC3537

1μF

ALKALINE

0.8V

TO

1.6V

3.3V

3V

2.2μH

R6

665k

ENLDO

FBB

FBL

ENBST

MODE

PGND

SGND

SW

R2

1.74M

R1

1M

R3

511k

R4

2.05M

R5

1.0M

4.7μF

1μF

ON

OFF

BURST

PWM

PGDL

PGDB

LBO

LBI

+