LTC1504ACS8-3.3 View Datasheet(PDF) - Linear Technology

Part Name

Description

MFG CO.

LTC1504ACS8-3.3

500mA Low Voltage Step-Down Synchronous Switching Regulator

Linear Technology 

BLOCK DIAGRAM

SHDN

TO INTERNAL BLOCKS

COMP

SS

SAW

12µA

–

PWM

+

LTC1504A

VCC

Q1

SW

Q2

ILIM

–+

IMAX

12µA

FB

+–

+–

VREF

1.265V

Figure 3. Block Diagram

FB

(ADJ ONLY)

20.4k

12.6k

SENSE

(–3.3V ONLY)

1504A • BD

TEST CIRCUITS

VCC +

CIN

100µF

NC

IMAX

VCC

SHDN

SW

1µF

LTC1504A

GND FB/SENSE

SS

COMP

LEXT

47µH

VOUT

+ COUT

220µF

CIN: AVX TPSE107M016R0125

COUT: SANYO 16CV220GX

LEXT: COILCRAFT D03316-473

0.1µF 7.5k

0.01µF

Figure 1

220pF

1504A • TC01

LTC1504A

A

FB/SENSE

–

B

+

VREF

A: TEST VOL, IOL

B: TEST VOH, IOH

Figure 2

COMP

1504A • TC02

APPLICATIONS INFORMATION

OVERVIEW

The LTC1504A is a complete synchronous switching

regulator controller (see Block Diagram). It includes two

on-chip 1.3Ω power MOSFETs, eliminating the need for

external power devices and minimizing external parts

count. The internal switches are set up as a synchronous

buck converter with a P-channel device (Q1) from the

input supply to the switching node and an N-channel

device (Q2) as the synchronous rectifier device from the

switching node to ground. An external inductor, input and

5

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