PAM2841 Datasheet, PDF (11/14 Pages) Power Analog Micoelectronics – 1.5ASW Current, 40V Precision WLED Driver

PAM2841
1.5A SW Current, 40V Precision WLED Driver
Layout Considerations
As for all switching power supplies, especially
those in high frequency and high current ones,
layout is an important design step. If layout is not
carefully done, the regulator could suffer from
instability as well as noise problems.
(1) Use separate traces for power ground and
signal ground. Power ground and signal ground
are connected together to a quite ground (input
connector)
(2) To prevent radiation of high frequency
resonance, proper layout of the high frequency
switching path is essential. Minimize the length
and area of all traces connecting to the SW pin.
The loop including the PWM switch, schottky
diode and output capacitor, contains high current
rising and falling in nanosecond and thus it
should be kept as short as possible.
(3) The input capacitor should be close to both
the VIN pin and the GND pin in order to reduce
the IC supply ripple.
(4) Keep the signal ground traces short and as
close to the IC as possible. Small signal
components should be placed as close as
possible to the IC, thus minimizing control signal
noise interference.
Layout Example
Top Layer
Bottom Layer
Power Analog Microelectronics,Inc
www.poweranalog.com
11
08/2008 Rev 1.3