ILC6377 Datasheet, PDF(1/11 Page) Impala Linear Corporation – 0.5A, 300KHZ, SO-8 PWM/PFM STEP DOWN CONVERTER WITH SHUTDOWN

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ILC6377 Datasheet, PDF (1/11 Pages) Impala Linear Corporation – 0.5A, 300KHZ, SO-8 PWM/PFM STEP DOWN CONVERTER WITH SHUTDOWN

Impala Linear Corporation

ILC6377

0.5A, 300kHz, SO-8 PWM/PFM Step Down

Converter with Shutdown

General Description

The ILC6377 is a 95% efficient, 300kHz step-down DC-DC

converter in an SO-8 package; capable of delivering 500mA

output current. The device is also capable of driving an

external FET for higher output current applications.

The ILC6377 uses a unique p-channel architecture with

built-in charge pump to maintain low on-resistance, even at

low input voltages. At high or normal currents the ILC6377

operates in PWM mode with 300kHz operating frequency.

When the load current drops and the device hits approxi-

mately 17% duty cycle, it automatically switches over to

PFM or pulse skipping mode. PFM (pulse frequency mod-

ulation) mode of operation extends efficiency at light loads.

Start-up is controlled via an external soft-start capacitor. The

device will automatically re-enter start-up mode when an

output current overload condition is sensed; thus providing

automatic short-circuit protection. Voltage lockout prevents

faulty operation below the minimum operating voltage level.

In shutdown, the ILC6377 consumes only 1.5mA current.

The ILC6377SO-XX offers fixed 3.3V or 5V ouput while

ILC6377SO-Adj allows adjustable output. Both versions of

ILC6377 are available in an SO-8 surface mount package.

Features

! Â±2.5% accurate output voltages

! Guaranteed 500mA output current

! 95% efficiency

! 55mA no load battery input current

! 1.5mA shutdown current

! Built in short circuit and overcurrent protection

! Undervoltage lockout and soft-start

! External transistor drive available for higher Iout

! 300kHz operation

! Automatic switchover to PFM mode at low

currents for longest battery life

! Fixed 3.3V or 5V or adjustable output

! SO-8 package

Applications

! Cellular Phones

! Palmtops and PDAs

! Portable Instrumentation

! Buck Converter for Industrial / Networking Applications

Block Diagram

VI N 1

VO UT 5

8 LX

S/ D, 4

So ftstar t, S /D,

Vref

V ref

with

S oft-

start

Error

A mp

P rotection

P WM /PFM

C ON TROLLER

PWM

C omp

RAMP WAVE

GEN ER ATOR,

OSC ILLATOR

GATE

DRIV ER

7 EXT1

2 EXT2

3 P_BST

6 GND

Pin Package Configurations

VI N 1

8 LX

EXT2 2 ILC6377 7 EXT1

P_BST 3

S/D, 4

CSS

(TOP VIE W)

6 GND

5 VO UT

ILC6377SO- XX

SO-8 Package

VI N 1

8 LX

EXT2 2 ILC6377 7 EXT1

P_BST 3

S/D, 4

CSS

(TOP VIE W)

6 GND

5 FB

ILC6377SO- Adj

SO-8 Package

ILC6377SO-33

ILC6377SO-50

ILC6377SO-Adj

Ordering Information

3.3V, 300 kHz step-down PWM/PFM converter

5V, 300 kHz step-down PWM/PFM converter

Adjustable, 300 kHz step-down PWM/PFM converter

Pin Description

Symbol

VIN

EXT2

P-BST

S/D

Softstart, Vref

VOUT/FB

GND

EXT1

Function

Power Supply

External gate drive pin (low when

P-Ch FET is ON)

P-Ch gate boost

Shutdown, also soft-start capacitor

pin and Vref output

Output voltage sense pin for

ILC6377SO-XX; 1V feedback for

ILC6377SO adj

Ground connection

External gate drive pin (low when

P-Ch FET is on)

Inductor switch pin

Impala Linear Corporation

ILC6377 1.3

(408) 574-3939 www.impalalinear.com

June 1999 1

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