SS

FB

SS

t

(ms) =

C6(nF)

V

1.1

C6(nF)

0.765

1.1

=

I

( A)

6

´

´

´

´

SW

VBST

EN

VFB

GND

VO

4

5

6

2

1

7

VIN

SS

VIN

VREG5

EN

Logic

SW

PGND

Protection

Logic

Ref

SS

UVLO

UVLO

Softstart

SS

REF

TSD

Ref

VREG5

8

VIN

Ceramic

Capacitor

3

SGND

SGND

PGND

PWM

+

-

+

OCP

+

-

VREG5

XCON

VREG5

Control Logic

1 shot

ON

SW

PGND

ZC

+

-

TPS54528

www.ti.com

SLVSAY4C – JULY 2011 – REVISED MARCH 2014

8 Detailed Description

8.1 Overview

The TPS54528 is a 5-A synchronous step-down (buck) converter with two integrated N-channel MOSFETs. It

operates using D-CAP2™ mode control. The fast transient response of D-CAP2™ control reduces the output

capacitance required to meet a specific level of performance. Proprietary internal circuitry allows the use of low

ESR output capacitors including ceramic and special polymer types.

8.2 Functional Block Diagram

8.3 Feature Description

8.3.1 Soft Start And Pre-Biased Soft Start

The soft start function is adjustable. When the EN terminal becomes high, 6

μA current begins charging the

capacitor which is connected from the SS terminal to GND. Smooth control of the output voltage is maintained

during start up. The equation for the slow start time is shown in Equation 1. VFB voltage is 0.765 V and SS

terminal source current is 6

μA.

(1)

Copyright © 2011–2014, Texas Instruments Incorporated

9

Product Folder Links: TPS54528