FB

SW

RTN

BST

1.225V

VILIM

LM25017

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

LM25017

SNVS951D – DECEMBER 2012 – REVISED DECEMBER 2014

www.ti.com

7 Detailed Description

7.1 Overview

The LM25017 step-down switching regulator features all the functions needed to implement a low cost, efficient,

buck converter capable of supplying up to 650 mA to the load. This high voltage regulator contains 48-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 regulator operation is based on a constant on-time control scheme

circuit protection while providing minimum fold-back.

The LM25017 device can be applied in numerous applications to efficiently regulate down higher voltages. This

regulator is well suited for 12-V and 24-V rails. Protection features include: thermal shutdown, Undervoltage

Lockout (UVLO), minimum forced off-time, and an intelligent current limit.

7.2 Functional Block Diagram

8

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