Datasheet

GND
GND
GND
R8
R12
C6
GND
R4
C11
L1
C12
R7
R2
R1
GND
GND
D2
GND
D1
R6
R3
GND
GND
GND
R5
R9
+
C1
GND
C2
C9
C10
C8
C5
C7
C3
VOUT
VBATT
+
C4
GND
GND
GND
GND
GND
R10
GND
R11
VReg
RSLEW
7
LPM
4
NC
1
SS
11
VSENSE
14
PH
17
BOOT
20
RST
8
CDLY
9
AGND
10
EN
5
NC
2
SYNC
3
RST_TH
13
OV_TH
12
VREG
16
VIN
19
VIN
18
RT
6
COMP
15
PAD
21
VIN
VReg
VReg
VReg
VReg
GND
TPS54262-Q1
SLVS996C –SEPTEMBER 2009–REVISED JUNE 2010 www.ti.com
APPLICATION INFORMATION
These guidelines address the following topics in detail for TPS54262-Q1.
1. Component selection
2. Design example
3. PCB layout guidelines
Component Selection
This section explains considerations for the external components selection. The following schematic shows the
interconnection between external components and the device for a typical DC/DC step down application.
Figure 31. Typical Application Schematic
1) Input Capacitors (C1, C11)
Input filter capacitor (C11) is used to filter out high frequency noise in the input line. Typical values of C11 are
0.1µF to 0.01µF. For higher frequency noise, low capacitor values are recommended.
To minimize the ripple voltage, input ceramic de-coupling capacitor (C1) of type X5R or X7R should be used.
The DC voltage rating for the input decoupling capacitor must be greater than the maximum input voltage. This
capacitor must have an input ripple current rating higher than the maximum input ripple current of the converter
for the application; and is determined by Equation 33.
(33)
The input capacitors for power regulators are chosen to have a reasonable capacitance-to-volume ratio and fairly
stable over temperature. The value of the input capacitance also determines the input ripple voltage of the
regulator, shown by Equation 34.
(34)
Input ceramic filter capacitors should be located in close proximity to the VIN terminal. Surface mount capacitors
are recommended to minimize lead length and reduce noise coupling.
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