7 Detailed Description

7.1 Overview

The TPS54KB2x device is a high-efficiency, single-channel, small-sized, synchronous buck converter. The

device suits low output voltage point-of-load applications with 25 A or lower output current in server, storage,

and similar computing applications. The TPS54KB2x features proprietary D-CAP4 mode control combined with

adaptive on-time architecture. This combination builds modern low-duty-ratio and ultra-fast load-step-response

DC/DC converters in an ideal fashion. The output voltage set by the feedback voltage divider ranges from the

internal voltage reference to 5.5 V. The conversion input voltage ranges from 2.7 V to 16 V, and the VCC input

voltage ranges from 3.13 V to 5.3 V. The D-CAP4 modulator uses emulated current information to control the

modulation. The D-CAP4 modulator reduces loop gain variation with different output voltages providing better

transient response in higher output voltage applications. An advantage of this control scheme is that it does

not require a phase-compensation network outside which makes the device easy-to-use and also allows low

external component count. Another advantage of this control scheme is that it supports stable operation with

all low ESR output capacitors (such as ceramic capacitors and low ESR polymer capacitors). Lastly, adaptive

on-time control tracks the preset switching frequency over a wide range of input and output voltages while

increasing switching frequency as needed during load-step transients.

7.2 Functional Block Diagram

PGND

SW

VIN

BOOT

ILIM

EN

GOSNS

FB

SS

PG

LDO

XCON

BOOT

REG

Enable

VIN

Control Logic

Valley Current

Limit

VCC

+

EN Threshold

Ramp

PWM

PG Driver

UV

Threshold

+

Enable

ThermalOK

OT Threshold

+

VCC UVLO

VCCOK

+

VIN UVLO

VINOK

PG/

OVP/

UVP

OCP

EN

VIN

VCC

PG

MSEL

HS FET

Gate

Drive

LS FET

Gate

Drive

OV

Threshold

+

–

RSA

+

–

+

–

AGND

EA

+

–

Reference

generator

VCC

PWM

Trigger

+

-

+

-

VCC

TJ

Zero Cross

Detection/

Negative OC

ZCD/

NOC

Output

Discharge

Adaptive on-time

Mode

Skip-mode/

FCCM

One-

shot

EN_SS

www.ti.com

TPS54KB20

SLVSGP3 – MAY 2023

Copyright © 2023 Texas Instruments Incorporated

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