APPLICATION INFORMATION

FUNCTIONAL BLOCK DIAGRAM

VIN

UVLO

ENABLE

Thermal

Protection

Reference

Overcurrent

GateDrive

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

FeedForward

BOOT

NC

POWERPAD

VIN

VOUT

5 µA

1.221VBandgap

SlowStart

Boot

Regulator

Error

Amplifier

Gain=25

PWM

Comparator

Protection

Gate

Driver

Control

VSENSE

DETAILED DESCRIPTION

Oscillator Frequency

Voltage Reference

Enable (ENA) and Internal Slow Start

TPS5430-Q1

The internal free running oscillator sets the PWM switching frequency at 500 kHz. The 500-kHz switching

frequency allows less output inductance for the same output ripple requirement resulting in a smaller output

inductor.

The voltage reference system produces a precision reference signal by scaling the output of a temperature

stable bandgap circuit. The bandgap and scaling circuits are trimmed during production testing to an output of

1.221 V at room temperature.

The ENA pin provides electrical on/off control of the regulator. Once ENA voltage exceeds the threshold voltage,

the regulator starts operation and the internal slow start begins to ramp. If ENA voltage is pulled below the

threshold voltage, the regulator stops switching and the internal slow start resets. Connecting the pin to ground

or to any voltage less than 0.5 V disables the regulator and activates the shutdown mode. The quiescent current

of the TPS5430 in shutdown mode is typically 18

µA.

Copyright © 2007–2009, Texas Instruments Incorporated

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Product Folder Link(s): TPS5430-Q1