RT/SD

FB

VIN

SW

RTN

BST

L1

C2

C4

C3

6V - 75V

Input

LM34923

R3

C1

SHUTDOWN

GND

VCC

GND

UV

UVO

UV STATUS

D1

LM34923

www.ti.com

SNVS695A – MARCH 2011 – REVISED FEBRUARY 2013

80-V 600-mA Constant On-Time Buck Switching Regulator

Check for Samples: LM34923

1

FEATURES

DESCRIPTION

The

LM34923

Step

Down

Switching

Regulator

2

•

Operating Input Voltage Range: 6V to 75V

features all of the functions needed to implement a

•

Integrated 80V, N-Channel Buck Switch

low cost, efficient Buck bias regulator. This high

•

Internal Start-up Regulator

voltage

regulator

contains

an

80V

N-Channel

MOSFET Switch and a startup regulator. The device

•

No Loop Compensation Required

is easy to implement and is provided in an 10-pin

•

Ultra-Fast Transient Response

VSSOP package. The regulator’s control scheme

•

Operating Frequency Remains Constant with

Line and Load Variations

feature results in the operating frequency remaining

relatively constant with line and load variations. The

•

Adjustable Output voltage From 2.5V

control scheme requires no loop compensation,

•

Precision Internal Reference, ±2.5%

resulting in fast transient response. An intelligent

•

Intelligent Current Limit Reduces Foldback

current limit is implemented with a forced off-time

•

Programmable Input UV Detector with Status

ensures short circuit control while providing minimum

Flag Output

foldback. Other features include: Thermal Shutdown,

•

Pre-charge Switch Enables Bootstrap Gate

VCC Under Voltage Lock-out, Max Duty Cycle

Drive with No Load

Limiter, a Pre-charge Switch, and a programmable

•

Thermal Shutdown

Under Voltage Detector with a status flag output.

•

10-Pin VSSOP Package

APPLICATIONS

•

Non-Isolated Telecommunication Buck

Regulator

•

Secondary High Voltage Post Regulator

•

+42V Automotive Systems

Typical Application, Basic Step-Down Regulator

1

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Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2

All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Copyright © 2011–2013, Texas Instruments Incorporated

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.