RT7257A
13
DS7257A-04 October 2016 www.richtek.com
©
Copyright 2016 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.
Layout Consideration
Follow the PCB layout guidelines for optimal performance
of the RT7257A.
Keep the traces of the main current paths as short and
wide as possible.
Put the input capacitor as close as possible to the device
pins (VIN and GND).
SW node is with high frequency voltage swing and
should be kept at small area. Keep analog components
away from the SW node to prevent stray capacitive noise
pick-up.
Connect feedback network behind the output capacitors.
Keep the loop area small. Place the feedback
components near the RT7257A.
An example of PCB layout guide is shown in Figure 9
for reference.
Figure 9. PCB Layout Guide
Table 3. Suggested Capacitors for C
IN
and C
OUT
Location Component Supplier Part No. Capacitance (F) Case Size
C
IN
MURATA GRM31CR61E106K 10 1206
C
IN
TDK C3225X5R1E106K 10 1206
C
IN
TAIYO YUDEN TMK316BJ106ML 10 1206
C
OUT
MURATA GRM31CR60J476M 47 1206
C
OUT
TDK C3225X5R0J476M 47 1210
C
OUT
MURATA GRM32ER71C226M 22 1210
C
OUT
TDK C3225X5R1C22M 22 1210
V
IN
V
OUT
GND
C
IN
GND
C
P
C
C
R
C
SW
V
OUT
C
OUT
L
R1
R2
Input capacitor must
be placed as close
to the IC as possible.
SW node is with high frequency voltage swing and should
be kept at small area. Keep analog components away from
the SW node to prevent stray capacitive noise pick-up
The feedback components
must be connected as close
to the device as possible.
BOOT
VIN
SW
GND
SS
EN
FB
COMP
GND
2
3
4
5
6
7
8
9
C
SS
GND
V
IN
R
EN
C
BOOT