LM3501 Datasheet, PDF (15/18 Pages) National Semiconductor (TI) – Synchronous Step-up DC/DC Converter for White LED Applications

Application Information (Continued)
to minimize copper trace connections that can inject noise
into the system. The ground connection for the current set-
ting resistor should connect directly to the GND pin. The
AGND pin should connect directly to the GND pin. Not
connecting the AGND pin directly, as close to the chip as
possible, may affect the performance of the LM3501 and
limit its current driving capability. Trace connections made to
the inductor should be minimized to reduce power dissipa-
tion, EMI radiation and increase overall efficiency. It is good
practice to keep the V_SW routing away from sensitive pins
such as the FB pin. Failure to do so may inject noise into the
FB pin and affect the regulation of the device. See Figure 3
and Figure 4 for an example of a good layout as used for the
LM3501 evaluation board.
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FIGURE 3. Evaluation Board Layout (2X Magnification)
Top Layer
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FIGURE 4. Evaluation Board Layout (2X Magnification)
Bottom Layer (as viewed from the top)
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