TPS56428_16 Datasheet, PDF (8/30 Pages) Texas Instruments – 4.5-V to 18-V Input, 4-A Sync. Step-Down Converter with Advanced Eco-mode

TPS56428
SLVSBV4B – APRIL 2013 – REVISED OCTOBER 2015
8 Detailed Description
www.ti.com
8.1 Overview
The TPS56428 is a 4-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. PG output can be used for sequence
operation.
8.2 Functional Block Diagram
EN
EN
1
EN
Logic
OCP
VFB
2
+25%
REF
SS
+
+PWM
-
AGND
VREG5
3
PGND
Softstart
SS
PG
4
+ REF
- -10%
OV
Control Logic
VREG5
1 shot
XCON
ON
VREG5
+ SW
ZC
- PGND
+
OCP
-
VIN
SW
PGND
VIN
VIN
8
VBST
7
SW
VO
6
Ceramic
Capacitor
5
GND
PGND
UVLO
VREG5
EN
REF
REF
OV
UVLO
TSD
Protection
Logic
Figure 7. Functional Block Diagram
8.3 Feature Description
8.3.1 PWM Operation
The main control loop of the TPS56428 is an adaptive on-time pulse width modulation (PWM) controller that
supports a proprietary D-CAP2™ mode control. D-CAP2™ mode control combines constant on-time control with
an internal compensation circuit for pseudo-fixed frequency and low external component count configuration with
both low ESR and ceramic output capacitors. It is stable even with virtually no ripple at the output.
8
Submit Documentation Feedback
Product Folder Links: TPS56428
Copyright © 2013–2015, Texas Instruments Incorporated