UM3502QA Datasheet, PDF (10/13 Pages) Union Semiconductor, Inc. – Low-Profile, 600mA, Synchronous Step-Down Converter with Integrated Inductor

UM3502QA
Layout Guidance
The package of the UM3502QA has been optimized that makes it easy for layout. It is an ideal
choice to be used to replace less efficient LDO to achieve improved efficiency in space restricted
applications.
When laying out the PC board, the following suggestions should be taken to ensure higher
performance of the UM3502QA.
1. PCB with at least two planes is recommended. Keep the GND plane under the converter as
complete as possible.
2. Connect the input capacitor C_IN to the PV_IN and PGND pins, the output capacitor C_OUT to the
V_OUT and PGND pins as closely as possible to get good power filter effect.
3. The power traces, including the PGND trace, the PV_IN trace and V_OUT trace should be kept
short, direct and wide to allow large current flow.
4. Connect AV_IN and AGND to a quiet point. The AGND pin is usually connected to the
GND plane by vias. The AV_IN pin should be directly connected to the positive electrode
of C_IN. A 0.1µF capacitor can also be used to decouple for better performance.
5. Keep the SW pin away from the sensitive FB node. This pin should also not be electrically
connected to any external signal, ground, or voltage.
6. Do not trace signal line under the chip.
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http://www.union-ic.com Rev.01 Nov.2015
10/13