Notes on PC Board Production
STK732C
• Capacitor C1 should be placed as close as possible to the pin 10 input in the layout. (This is to prevent voltage drops in
the input lines and pattern. Also, a separate smoothing capacitor is required if the input is a direct current input using
rectified and smoothed AC.)
• Capacitor C2 should be placed as close as possible to the load in the layout. (This is to compensate for voltage drops
due to load fluctuations.)
• Pins 2 and 5 are voltage sensing lines, and should be connected close to the load, i.e., close to C2. (This is to
compensate for voltage drops in the pattern.)
• Pins 3 and 4 should be directly connected to the two terminals of the current detection resistor Rs1. (This is to prevent
detection based on pattern resistances.)
• Pin 6 should be connected to the capacitor C1 ground using a thick, short line to reduce the related loop area. (This is
to reduce switching spikes.)
• Power lines, i.e., lines that carry current, should be made as wide as possible in the pattern.
• When a ripple suppression LC filter is added, connect it at the location indicated by dotted lines in the figure. The
sensing line from pin 2 should be connected to the same position (the C2 location) as it is when no filter is used.
• C5 and R1, which are used to reduce switching spikes, should be connected as close as possible to the IC pins.
• Locations where multiple pins are used (pins 7 and 8, and pins 9 and 10) must be connected in the printed circuit
pattern.
Output On/Off Control (cutoff)
The on/off control function uses pin 12. When pin 12 is at the low level, the output will be cut off.
Connection diagram for circuits that do not
use the cutoff function.
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