1

LT1572

100kHz, 1.25A Switching

Regulator with Catch Diode

Boost Converter Efficiency

L0AD CURRENT (mA)

0

80

90

100

200

LT1572 • TA01

70

60

50

50

100

150

250

BOOST CONVERTER

DESCRIPTIO

S

FEATURE

s

Catch Diode Included in Package

s

Wide Input Voltage Range: 3V to 30V

s

Low Quiescent Current: 6mA

s

Internal 1.25A Switch

s

Very Few External Parts Required

s

Self-Protected Against Overloads

s

Operates in Nearly All Switching Topologies

s

Shutdown Mode Draws Only 50

µA Typical Current

s

Can Be Externally Synchronized

The LT

regulator with on-board switch and catch diode included

in one package. It combines an LT1172 with a 1A Schottky

catch diode. The LT1572 can be operated in all standard

switching configurations, including boost, buck, SEPIC,

flyback, forward, inverting and “Cuk”. All necessary con-

trol, oscillator and protection circuitry is included on the

die with the high efficiency switch. This makes the part

extremely easy to use and provides “bustproof” operation

similar to that obtained with 3-pin linear regulators.

The LT1572 operates with supply voltages from 3V to 30V

and draws only 6mA quiescent current. It can deliver load

power up to 15W with no external power devices. By

utilizing a current mode switching technique, the LT1572

achieves excellent response to load and line transients.

The LT1572 has many unique features not found on the

more difficult to use control chips presently available. It

uses adaptive anti-sat switch drive to allow very wide

ranging load currents with no loss in efficiency. An exter-

nally activated shutdown mode reduces total supply cur-

rent to 50

µA typical for standby operation. External syn-

chronizing of switching frequency is possible, with a range

of 120kHz to 160kHz.

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APPLICATI

s

3.3V-to-5V and 5V-to-12V Boost Converters

s

Negative-to-Positive Converter

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SEPIC Converter (Input Can Be Greater or

Less Than Output)

s

Battery Charger

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

APPLICATI

TYPICAL

LT1572 • TA01

R1

10.7k

1%

+

C1

1

µF

R2

1.24k

1%

LT1572

GND

E2

E1

L1*

50

µH

†

15

14

3

2

11

9

R3

1k

5

4, 13

12

10

COILTRONICS CTX50-2

AVX TPS OR SPRAGUE 593D

ALWAYS CONNECT BOTH ANODE (2, 15)

AND CATHODE (3, 14) PINS

*

**

†

CATHODE

†

FB

12V

0.25A

4.5V

TO 10V

C3

100

µF

10V

100

µF

16V

5V-to-12V Boost Converter