STR-A6331 Ver la hoja de datos (PDF) - Sanken Electric co.,ltd.
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STR-A6331 Datasheet PDF : 17 Pages
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STR-A6300 Application Notes
（Ver.1.2）
However, when the phase compensation by the secondary side error-amplifier is not sufficient, due to the
quite large ripple of a smoothing capacitor or unique loads specifications, it is effective to insert the capacitor,
C6, in the range of 0.01~0.1uF at both ends of the primary side photo-transistor as displayed on Fig. 12.
In this case, it is necessary to connect a diode, D6, which is for preventing reverse current, to the
photo-transistor in series.
In case of a wide input, the variation of intermittent oscillating frequency is quite large because of unstable
AC input voltage. Converting the start-up resistor area to a constant current circuit can reduce rattling noise
produced at low AC input voltage.
9.5 Notes for PCB layouts for Switching Power Supply with PRC operation in using STR-A6300
Series
As shown on Fig. 13, the connection from pin 2 to R5(GND side) should be as short and wide as possible.
Nearest to the R5, the pattern to pin 5 should be isolated from that of both the electrolyte input capacitor and
the voltage resonance capacitor. In addition, pin 2(GND) and pin 5(GND) should be connected through
external pattern as short as possible. The pattern width is 1A/1mm or wider, and C2(C2’), C3, C5, and R3
should be connected on this pattern. In case the pattern from the IC to the C2 is far, the capacitor, C2, in the
range of 0.01~0.1uF approx. should be connected near the IC.
As wide and short as
possible
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C2
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R4
C4
C5
R5
AC IN
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9.6 Notes for Mounting Design
Where PCB pattern and mounting conditions are applied improperly, malfunction, noise, and loss might
occur. Based on the principle of “wider and shorter”, line impedance can be lowered by making
thicker pattern where a high frequency current flows, and by making shorter wiring between
components. As shown on Fig. 14, where high frequency current makes a loop, the pattern should be
designed in order the area inside the loop(the shaded area) to keep minimized. Especially, the ground
and the earth line described by slashed lines in Fig.14, which considerably affect radiant noise, should
be as short and wide as possible. In the switching power supply, as there are current circuits where
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