Datasheet

SW
VBST
EN
VO
VFB
GND
PGND
VO
4
6
9
10
11
1
2
7
12
VIN
SS
VIN
VREG5
EN
Logic
UV
OV
Protection
Logic
Ref
SS
UV
OV
UVLO
UVLO
Softstart
SS
REF
TSD
Ref
VREG5
5
PG
1mF
13
8
VCC
Ceramic
Capacitor
3
SGND
SGND
PGND
VCC
+20%
-10%
Ref
VREG5
Control logic
1 shot
XCON
-30%
OCP
SW
PGND
ZC
SW
PGND
14
VREG5
TPS54225
SLVSA15C –OCTOBER 2009– REVISED FEBRUARY 2011 www.ti.com
Functional Block Diagram
OVERVIEW
The TPS54225 is a 2-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.
DETAILED DESCRIPTION
PWM Operation
The main control loop of the TPS54225 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.
At the beginning of each cycle, the high-side MOSFET is turned on. This MOSFET is turned off after internal one
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Product Folder Link(s): TPS54225