RT9178
It should be noted that stability problems have been seen
in applications where
“vias”
to an internal ground plane
were used at the ground points of the device and the input
and output capacitors. This was caused by varying ground
potentials at these nodes resulting from current flowing
through the ground plane. Using a single point ground
technique for the regulator and it’ s capacitors fixed the
problem. Since high current flows through the traces going
into V
IN
and coming from V
OUT
, Kelvin connect the capacitor
leads to these pins so there is no voltage drop in series
with the input and output capacitors.
Optimum performance can only be achieved when the
device is mounted on a PC board according to the diagram
below:
BP
V
OUT
V
IN
GND
EN
SOT-23-5 Board Layout
www.richtek.com
10
DS9178-16 April 2008
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
