1

LT1317/LT1317B

Micropower, 600kHz PWM

DC/DC Converters

FEATURES

The LT

step-up DC/DC converters that operate over a wide input

voltage range of 1.5V to 12V. The LT1317 features auto-

matic shifting to power saving Burst Mode

light loads. High efficiency is maintained over a broad

300

µA to 200mA load range. Peak switch current during

Burst Mode operation is kept below 250mA for most

operating conditions which results in low output ripple

voltage, even at high input voltages. The LT1317B does

not shift into Burst Mode operation at light loads, eliminat-

ing low frequency output ripple at the expense of light load

efficiency.

The LT1317/LT1317B contain an internal low-battery de-

tector with a 200mV reference that stays alive when the

device goes into shutdown.

No-load quiescent current of the LT1317 is 100

µA and

shuts down to 30

µA. The internal NPN power switch

handles a 500mA current with a voltage drop of just

300mV.

The LT1317/LT1317B are available in MS8 and SO-8

packages.

s

100

µA Quiescent Current

s

s

600kHz Fixed Frequency Operation

s

Starts into Full Load

s

Low-Battery Detector Active in Shutdown

s

Automatic Burst Mode Operation at

Light Load (LT1317)

s

Continuous Switching at Light Loads (LT1317B)

s

s

Pin for Pin Compatible with the LT1307/LT1307B

s

Cellular Telephones

s

Cordless Telephones

s

Pagers

s

GPS Receivers

s

Battery Backup

s

Portable Electronic Equipment

s

Glucose Meters

s

Diagnostic Medical Instrumentation

Burst Mode is a trademark of Linear Technology Corporation.

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

Figure 1. 2-Cell to 3.3V Boost Converter

SW

FB

LT1317

L1

10

µH

D1

LBO

LBI

SHDN

SHUTDOWN

33k

R2*

604k

1%

3.3V

200mA

R1

1M

1%

3.3nF

1317 F01

C1

47

µF

C2

47

µF

2

CELLS

D1: MBR0520

L1: SUMIDA CD43-100

* FOR 5V OUTPUT, R2 = 332k, 1%

GND

+

+

2-Cell to 3.3V Converter Efficiency

LOAD CURRENT (mA)

50

60

70

80

90

0.3

10

100

1000

1317 TA01

40

1