1

LT1309

The LT

for Flash Memory. The regulator features Burst Mode

TM

operation with a 0.5A, 300mV switch, enabling 85%

efficiency at the fixed 12V output. High frequency opera-

tion permits the use of small value, and therefore small

size, surface mount inductors and capacitors. The LT1309

comes in an 8-lead SO package allowing extremely

compact PC board layouts. These features make the

device attractive for PCMCIA cards, cellular phones and

other applications where PC board space is limited.

Quiescent current is 650

µA decreasing to 9µA when the

part shuts down. The device includes a soft start feature

which limits supply current transients during turn-on.

The LT1309 contains a VPP VALID comparator with a

logic output that goes low when the output voltage is

ready to program 12V Flash Memory. This comparator

simplifies the interface to external control logic.

500kHz Micropower

DC/DC Converter

for Flash Memory

S

FEATURE

DESCRIPTIO

s

60mA Output Current at 12V from 3V or 5V Supply

s

Shutdown to 9

µA

s

VPP VALID Comparator

s

Up to 85% Efficiency

s

Switching Frequency: 500kHz (Typical)

s

Quiescent Current: 650

µA

s

s

Soft Start Reduces Supply Current Transients

s

Uses Low Value, Small Size,

Surface Mount Inductors

s

Available in 8-Lead SO Package

APPLICATI

TYPICAL

12V, 60mA Flash Memory Programming Supply

12V Output Efficiency

LOAD CURRENT (mA)

1

70

72

74

76

78

86

10

100

LT1309 • TA02

80

82

84

L1*

10

µH

D1

†

VPP 12V, 60mA

SENSE

VPP VALID

LT1309

ON/OFF

VPP VALID

R1

1M

LT1309 • TA01

C3

0.1

µF

C2

1

µF**

C1

4.7

µF

MURATA ERIE LQH3C100K0YM00

CERAMIC

MOTOROLA MBR0530

*

**

†

ON/OFF

3.3V TO 5V

SOFT

START

PGND

GND

+

S

APPLICATI

s

Flash Memory VPP Generators

s

Type II and III PCMCIA Card DC/DC Converters

s

3V to 12V, 5V to 12V Converters

s

Portable Computers and Instruments

s

Cellular Telephones

s

DC/DC Converter Module Replacements

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

Burst Mode is a trademark of Linear Technology Corporation.