BOOT

SW

VIN

EN

-

+

+

LS MOSFET

Current Limit

Oscillator

Maximum

Clamp

Overload

Recovery

Soft Start

Voltage

Reference

Slope

Compensation

HS MOSFET

Current

Comparator

Minimum Clamp

Pulse Skip

Power Stage

And

Dead time

Control

Logic

Boot UVLO

Boot Charge

UVLO

Thermal

Hiccup

Shutdown

Logic

ERROR AMPLIFIER

Regulator

VIN

-

+

OV comparator

0.6V

Current

Sense

Current

Sense

FB

GND

Hiccup

Shutdown

Hiccup

Shutdown

EN Compatator

Ih

30kohm

2.2nF

2pF

8

TPS54202H

SLVSDG7 – APRIL 2016

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Product Folder Links: TPS54202H

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Copyright © 2016, Texas Instruments Incorporated

7 Detailed Description

7.1 Overview

The device is a 28-V, 2-A, synchronous step-down (buck) converter with two integrated n-channel MOSFETs. To

improve performance during line and load transients the device implements a constant-frequency, peak current

mode control which reduces output capacitance. The optimized internal compensation network minimizes the

external component counts and simplifies the control loop design.

The TPS54202H’s switching frequency is fixed to 500 kHz.

The TPS54202H starts switching at VIN equal to 4.5 V. The operating current is 45

μA typically when not

switching and under no load. When the device is disabled, the supply current is 2 µA typically.

The integrated 148-m

Ω high-side MOSFET and 78-mΩ allow for high efficiency power supply designs with

continuous output currents up to 2 A.

The TPS54202H reduces the external component count by integrating the boot recharge diode. The bias voltage

for the integrated high-side MOSFET is supplied by an external capacitor on the BOOT to PH pins. The boot

capacitor voltage is monitored by an UVLO circuit and will turn the high-side MOSFET off when the voltage falls

below a preset threshold of 2.1 V typically.

The device minimizes excessive output overvoltage transients by taking advantage of the overvoltage

comparator. When the regulated output voltage is greater than 108% of the nominal voltage, the overvoltage

comparator is activated, and the high-side MOSFET is turned off and masked from turning on until the output

voltage is lower than 104%.

The TPS54202H device has internal 5-ms soft-start time to minimize inrush currents.

7.2 Functional Block Diagram