LM3661TL-1.25 NSC [National Semiconductor], LM3661TL-1.25 Datasheet - Page 15

• Manufacturer Part Number: LM3661TL-1.25
• Description: 450mA Subminiature, Micropower Step-Down DC-DC Converter for Ultra Low-Voltage Circuits
• Manufacturer: NSC [National Semiconductor]

Application Information
to perform these functions. The ESR, or equivalent series
resistance, of the filter capacitors is a major factor in voltage
ripple. Table 3 lists suggested capacitors suppliers.
Model
Input Filter Capacitor (10µF, 6.3V, X5R or X7R9
C2012X5R0J106M
JMK212BJ106MG
GRM21BR60J106K
Output Filter Capacitor (22µF, 6.3V, X5R or X7R9
C3225X5R0J226M
JMK325BJ226MG
GRM32DR60J226K
Table 3. Suggested capacitors and Suppliers
Size (EIA)
2012 (0805)
2012 (0805)
2012 (0805)
3225(1210)
3225(1210)
3225(1210)
(Continued)
Vendor
TDK
Taiyo-Yuden
muRata
TDK
Taiyo-Yuden
muRata
15
BOARD LAYOUT CONSIDERATION
PC board layout is an important part of DC-DC converter
design. Poor board layout can disrupt the performance of a
DC-DC converter and surrounding circuitry by contributing
EMI, ground bounce, and resistive voltage loss in the traces.
Below are layout recommendation to maximize device per-
formance: 1) Place the inductor and filter capacitors close
together and minimize the traces between components as
they carry relatively high switching current and act as anten-
nas. 2) Use wide traces between the power components and
for power connections to DC-DC converters circuit. 3) Route
noise sensitive traces such as the voltage feedback path
away from noisy power components. 4) Connect the ground
pins and filter capacitors together via a ground plane to
prevent switching current circulating through the ground
plane. Additional information regarding Micro SMD package
layout can be found in Application note AN-1112.
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