FB

VIN

VCC

SW

RTN

BST

2.5V

Vth

Input

RT/SD

CURRENT

LIMIT

+

-

VCC UVLO

ON/OFF

TIMERS

DRIVER

LOGIC

0.9 V

2. 85 V

OVER- VOLTAGE

START -UP

REGULATOR

FEEDBACK

THERMAL

SHUTDOWN

Current

Limit

One- Shot

2.5V

LG

UVO

UV

5 PA

PRE-

CHARGE

C1

C3

L1

C4

D1

C2

R3

LM5006

Delay

Delay

C5

LM5006

SNVS646A – FEBRUARY 2011 – REVISED FEBRUARY 2011

www.ti.com

Block Diagram

FUNCTIONAL DESCRIPTION

The LM5006 Step Down Switching Regulator features all the functions needed to implement a low cost, efficient,

Buck bias power converter. This high voltage regulator contains an 80 V N-Channel Buck Switch, is easy to

implement and is provided in the VSSOP-10 package. The regulator is based on a control scheme using an on-

control while providing minimum foldback.

The LM5006 can be applied in numerous applications to efficiently regulate down higher voltages. This regulator

is well suited for 48 Volt Telecom and the new 42V Automotive power bus ranges. Features include: Thermal

current limit off timer, a pre-charge switch, a programmable under voltage detector with status flag, and a gate

driver output for a synchronous rectifier.

Control Circuit Overview

The LM5006 is a Buck DC-DC regulator that uses a control scheme in which the on-time varies inversely with

(FB) compared to an internal reference (2.5V). If the FB level is below the reference the buck switch is turned on

switch remains off for at least the minimum off-timer period of 260 ns. If FB is still below the reference at that

time the switch turns on again for another on-time period. This continues until regulation is achieved.

10

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