LM3668_08 Datasheet, PDF (15/18 Pages) National Semiconductor (TI) – 1A, High Efficiency Dual Mode Single Inductor Buck-Boost DC/DC Converter

TABLE 1. Suggested Capacitors and Suppliers
Model
Type
Vendor
10 µF for C_IN (For 4.5/5V option, use 10V or higher rating capacitor)
GRM21BR60J106K
Ceramic, X5R
Murata
JMK212BJ106K
Ceramic, X5R
Taiyo-Yuden
C2012X5R0J106K
Ceramic, X5R
TDK
LMK212 BJ106MG (+/-20%) Ceramic, X5R
Taiyon-Yuden
LMK212 BJ106KG (+/-10%) Ceramic, X5R
Taiyon-Yuden
22 µF for C_OUT (For 4.5/5V option, use 10V or higher rating capacitor)
JMK212BJ226MG
Ceramic, X5R
Taiyo-Yuden
LMK212BJ226MG
Ceramic, X5R
Taiyo-Yuden
Voltage Rating
6.3V
6.3V
6.3V
10V
10V
6.3V
10V
Case Size
Inch (mm)
0805 (2012)
0805 (2012)
0805 (2012)
0806(2012)
0805(2012)
0805 (2012)
0805 (2012)
Layout Considerations
As for any high frequency switcher, it is important to place the
external components as close as possible to the IC to maxi-
mize device performance. Below are some layout recommen-
dations:
1) Place input filter and output filter capacitors close to the IC
to minimize copper trace resistance which will directly effect
the overall ripple voltage.
2) Route noise sensitive trace away from noisy power com-
ponents. Separate power GND (Noisy GND) and Signal GND
(quiet GND) and star GND them at a single point on the PCB
preferably close to the device GND pin.
3) Connect the ground pins and filter capacitors together via
a ground plane to prevent switching current circulating
through the ground plane. Additional layout consideration re-
garding the LLP package can be found in Application AN
1187.
15
www.national.com