LM5165 datasheet(13/52 Pages) TI

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7 Detailed Description

7.1 Overview

The LM5165-Q1 converter is an easy-to-use synchronous buck DC-DC regulator that operates from a 3-V to

65-V supply voltage. The device is intended for step-down conversions from 3.3-V, 5-V, 12-V, 24-V, and 48-V

unregulated, semi-regulated and fully-regulated supply rails. With integrated high-side and low-side power

MOSFETs, the LM5165-Q1 delivers up to 150-mA DC load current with high efficiency and ultra-low input

quiescent current in a very small solution size. Designed for simple implementation, a choice of operating

modes offers flexibility to optimize its usage according to the target application. In constant on-time (COT)

mode of operation, ideal for low-noise, high current, fast load transient requirements, the device operates with

predictive on-time switching pulse. A quasi-fixed switching frequency over the input voltage range is achieved

by using an input voltage feedforward to set the on-time. Alternatively, pulse frequency modulation (PFM)

mode, complemented by an adjustable peak current limit, achieves exceptional light-load efficiency performance.

Control loop compensation is not required with either operating mode, reducing design time and external

component count.

The LM5165-Q1 incorporates other features for comprehensive system requirements, including an open-drain

Power Good circuit for power-rail sequencing and fault reporting, internally-fixed or externally-adjustable soft-

start, monotonic start-up into prebiased loads, precision enable with customizable hysteresis for programmable

line undervoltage lockout (UVLO), adjustable cycle-by-cycle current limit for optimal inductor sizing, and thermal

shutdown with automatic recovery. These features enable a flexible and easy-to-use platform for a wide range of

applications. The pin arrangement is designed for simple Layout, requiring only a few external components.

7.2 Functional Block Diagram

LM5165

CURRENT

LIMIT

VDD UVLO

ON-TIME ONE

SHOT

LDO BIAS

REGULATOR

VIN

FEEDBACK

ENABLE

THERMAL

SHUTDOWN

VIN UVLO

ZERO CROSS

DETECT

VDD

I-LIMIT

ADJUST

Control

Logic

VIN

OUT

HYSTERETIC

MODE

REFERENCE

SOFT-START

ENABLE

VOLTAGE

REFERENCE

1.223 V

VIN

1.212 V

1.144 V

HYS

ILIM

VOUT/FB

GND

PGOOD

1.150 V

1.064 V

(1)

Note:

(1) R1, R2 are implemented in the xed output voltage versions only.

www.ti.com

LM5165-Q1

SNVSAJ3C – MARCH 2016 – REVISED DECEMBER 2022

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