Shindengen Electric MFG.CO.,LTD

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6.1.6 Phase correction

In an RCC circuit, delays in the phase of the photocoupler, capacitor, or coil may result in hunting. If so, oscillations

may become audible or output voltage ripples may become very large. The following countermeasures are

available:

(1)

Insert C and R between the cathode and

REF of the shunt regulator.

(2)

Insert C and R between the front of the

secondary LC filter and REF of the shunt

regulator.

Output

Output

(3)

Insert C and R between the rear of the

secondary LC filter and REF of the shunt

regulator.

(4)

Place the power supply side of the

photocoupler in front of the LC filter.

Output

Output

If the oscillation tends to be intermittent under light load, one solution is to lower the feedback gain. Insert a

resistor as shown in Fig. 6.11. Set the resistor to 2.2 k

Ω or less.

MR4000

D112

PH111

C115

R117

2

4

3

Fig. 6.11 Lowering feedback gain

6. Supplementary design information