FB

VIN

VCC

SW

AGND

BST

2.0 V

VILIM

LM5161

RON

CURRENT LIMIT

COMPARATOR

+

-

VCC UVLO

ON/OFF

TIMERS

CONSTANT

ON-TIME

CONTROL

LOGIC

1.24 V

VCC

REGULATOR

FEEDBACK

COMPARATOR

DISABLE

THERMAL

SHUTDOWN

EN/UVLO

STANDBY

SHUTDOWN

BIAS

REGULATOR

0.35 V

20 µA

FPWM

SS

CURRENT

LIMIT TIMER

PGND

GM ERROR

AMP

DIODE

EMULATION

L

Copyright © 2016, Texas Instruments Incorporated

11

LM5161-Q1

www.ti.com

SNVSAF9 – AUGUST 2016

Product Folder Links: LM5161-Q1

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Copyright © 2016, Texas Instruments Incorporated

7 Detailed Description

7.1 Overview

The LM5161-Q1 step-down switching regulator features all the functions needed to implement a low-cost,

efficient buck converter capable of supplying 1-A to the load. This high voltage regulator contains 100-V N-

channel buck and synchronous rectifier switches and is available in the 14-pin HTSSOP package. The regulator

This feature maintains a relatively constant operating frequency with load and input voltage variations. A constant

on-time switching regulator requires no loop compensation resulting in fast load transient response. Peak current

limit detection circuit is implemented with a forced OFF-time during current limiting which is inversely proportional

numerous end equipment systems requiring efficient step-down regulation from higher input voltages. This

regulator is well suited for 24 V industrial systems as well as for 48 V telecom and PoE voltage ranges. The

LM5161-Q1 integrates an under-voltage lockout (EN/UVLO) circuit to prevent faulty operation of the device at

low input voltages and features intelligent current limit and thermal shutdown to protect the device during

overload or short circuit.

All instances of the LM5161 device name used throughout this document, in block diagrams and application

schematics, are valid for LM5161-Q1 as well, unless stated otherwise.

7.2 Functional Block Diagram