FB

SW

RTN

BST

1.225V

VILIM

LM34927

ILIM

COMPARATOR

+

-

V UVLO

ON/OFF

TIMERS

COT CONTROL

LOGIC

1.225V

START-UP

REGULATOR

FEEDBACK

DISABLE

THERMAL

SHUTDOWN

UVLO

OVER-VOLTAGE

1.62V

UVLO

4.5V

SD

SHUTDOWN

VDD REG

BG REF

0.66V

20 µA

CURRENT

LIMIT

ONE-SHOT

LM34927

www.ti.com

SNVS799G – APRIL 2012 – REVISED DECEMBER 2014

7 Detailed Description

7.1 Overview

The LM34927 step-down switching regulator features all the functions needed to implement a low-cost, efficient,

isolated-bias supply. This high-voltage regulator contains 100 V, N-channel buck and synchronous switches, is

easy to implement, and is provided in thermally enhanced SO PowerPAD-8 and WSON-8 packages. The

This control scheme does not require loop compensation. Current limit is implemented with forced off-time

The simplified block diagram of the LM34927 device is shown in Functional Block Diagram.

The LM34927 device can be applied in numerous applications to efficiently regulate down higher voltages. This

regulator is well suited for 48-V telecom and automotive power bus ranges. Protection features include: thermal

shutdown, UVLO, minimum forced off-time, and an intelligent current limit.

7.2 Functional Block Diagram

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Product Folder Links: LM34927