VIN

UVLO

ENABLE

Thermal

Protection

Reference

Overcurrent

Gate Drive

Oscillator

Ramp

Generator

VREF

PH

ENA

GND

BOOT

Z1

Z2

SHDN

SHDN

SHDN

SHDN

SHDN

SHDN

SHDN

SHDN

VIN

112.5% VREF

VSENSE

OVP

HICCUP

HICCUP

SHDN

NC

Feed Forward

BOOT

NC

POWERPAD

VIN

VOUT

5 µA

1.221 V Bandgap

Slow Start

Boot

Regulator

Error

Amplifier

Gain = 25

PWM

Comparator

Protection

Gate

Driver

Control

VSENSE

Copyright © Texas Instruments Incorporated

10

TPS5430, TPS5431

SLVS632I – JANUARY 2006 – REVISED APRIL 2017

www.ti.com

Product Folder Links: TPS5430 TPS5431

Submit Documentation Feedback

Copyright © 2006–2017, Texas Instruments Incorporated

7 Detailed Description

7.1 Overview

The TPS543x is a 3-A, step-down (buck) regulator with an integrated high-side n-channel MOSFET. The

TPS5431 is intended to operate from power rails up to 23 V and the TPS5430 up to 36 V. These devices

implement constant-frequency voltage-mode control with voltage feed forward for improved line regulation and

line transient response. Internal compensation reduces design complexity and external component count.

The integrated 110-mΩ high-side MOSFET supports high-efficiency power-supply designs capable of delivering

3-A of continuous current to a load. The gate-drive bias voltage for the integrated high-side MOSFET is supplied

by a bootstrap capacitor connected from the BOOT to PH pins. The TPS543x reduces the external component

count by integrating the bootstrap recharge diode.

The TPS543x has a default input start-up voltage of 5.3 V typical. The ENA pin can be used to disable the

TPS543x reducing the supply current to 18 µA. An internal pullup current source enables operation when the

ENA pin is floating. The TPS543x includes an internal slow-start circuit that slows the output rise time during start

up to reduce in rush current and output voltage overshoot. The minimum output voltage is the internal 1.221-V

feedback reference. Output overvoltage transients are minimized by an Overvoltage Protection (OVP)

comparator. When the OVP comparator is activated, the high-side MOSFET is turned off and remains off until

the output voltage is less than 112.5% of the desired output voltage.

Internal cycle-by-cycle overcurrent protection limits the peak current in the integrated high-side MOSFET. For

continuous overcurrent fault conditions the TPS543x will enter hiccup mode overcurrent limiting. Thermal

protection protects the device from overheating.

7.2 Functional Block Diagram