ncp1529 ON Semiconductor, ncp1529 Datasheet - Page 13

• Manufacturer Part Number: ncp1529
• Description: High Efficiency Dc-dc Converters
• Manufacturer: ON Semiconductor

Electrical Layout Considerations
requires respect of some rules to get a powerful portable
application. Good layout is key to prevent switching
regulators to generate noise to application and to
themselves.
Electrical layout guide lines are:
•
•
•
V
Table 4. LIST OF OUTPUT CAPACITOR
GND Plane
Taiyo Yuden
Implementing a high frequency DC-DC converter
IN
Use short and large traces when large amount of current
is flowing.
Keep the same ground reference for input and output
capacitors to minimize the loop formed by high current
path from the battery to the ground plane.
Isolate feedback pin from the switching pin and the
current loop to protect against any external parasitic
signal coupling. Add a feed-forward capacitor between
V
participates to the good loop stability. A 18 pF
DV
Figure 29. TSOP-5 Recommended Board Layout
Trace
Murata
OUT
TDK
OUT
and FB which adds a zero to the loop and
+ DI
L
GRM188R60J475KE
GRM21BR71C475KA
GRM188R60OJ106ME
JMK212BY475MG
JMK212BJ106MG
C2012X5R0J475
C1608X5R0J475
C2012X5R0J106
FB Trace
4
f
SW
1
EN Trace
C
OUT
) ESR
LAYOUT CONSIDERATIONS
4.7 muF
Trace
Trace
V
4.7 mF
4.7 mF
10 mF
10 mF
10 mF
SW
OUT
(eq. 6)
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NCP1529
13
Feed-Forward Capacitor Selection
response and is critical to obtain good loop stability. Given
that the compensation is internally fixed, an 18 pF ceramic
capacitor is needed. Choose a small ceramic capacitor X7R
or X5R or COG dielectric.
will help NCP1529 noise immunity and loop stability.
Thermal Layout Considerations
consideration such as:
•
•
•
requirements, UDFN6 package using exposed pad
connected to main radiator is recommended. Refer to
Notes 7, 8, and 9.
The feed-forward capacitor sets the feedback loop
A four layer PCB with a ground plane and a power plane
High power dissipation in small package leads to thermal
For high ambient temperature and high power dissipation
capacitor is recommended to meet compensation
requirements.
Enlarge V
power plane.
Connect GND pin to top plane.
Join top, bottom and each ground plane together using
several free vias in order to increase radiator size.
Figure 30. UDFN6 Recommended Board Layout
FB Trace
V
IN
IN
Trace
trace and added several vias connected to
GND Plane
EN Trace
Trace
Trace
V
SW
OUT