MR4530 datasheet(37/43 Pages) SHINDENGEN

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Shindengen Electric MFG.CO.,LTD

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6.7 Troubleshooting list

The table below shows common problems with power supply designs using the MR4000 Series, possible causes, and

solutions.

Problem

Possible cause

Solution

The polarity of the transformer is

incorrect.

Check winding directions for NP, NS, and NC.

Adjust the droop compensation circuit.

The droop compensation circuit is

inadequate.

The ON range setting (resistance between the F/B pin and

GND pin) is small.

A constant current load or constant

power load is used.

Change to a constant resistance load.

Adjust the number of turns in the NC coil.

Review the transformer coil structure.

Combine a zener diode and a resistor to clamp VCC.

The overvoltage latch is on.

Insert a resistor between the NC coil and rectification

diode.

The input to the Z/C pin is incorrect.

Review the circuit around the Z/C pin.

The IC is activated under a heavy

load.

Startup under a light load is recommended for the MR4000

Series.

Ton(max) has reached the limit value.

Review the transformer design.

1 Does not start up.

There are too few turns in the NC coil. Adjust the number of turns in the NC coil.

Review the core

ΔB.

The transformer is causing magnetic

saturation.

Adjust the resistance between the F/B pin and GND pin.

Adjust the droop compensation circuit.

The droop compensation circuit is

inadequate.

Adjust the resistance between the F/B pin and GND pin.

Provide a snubber circuit.

Review the transformer design.

MR4000 Series is

defective.

The voltage exceeded the withstand

level of the main switching device.

Review the transformer coil structure.

A control output

voltage rises.

Adjust the current limiting resistance

of the photodiode.

Adjust the current limiting resistance of the photodiode.

Add a dummy resistor or damper resistor at the output

end.

A non-control

output voltage

rises.

Peak charging to the output capacitor

due to a surge voltage

Review the transformer design.

The constants for the output voltage

detection circuit are inappropriate.

Reexamine the output voltage detection resistance.

Adjust the resistance between the F/B pin and GND pin.

The droop compensation circuit is

inadequate.

Adjust the OCL resistance.

Increase the oscillation frequency.

The output voltage

or current does not

reach the desired

level.

Ton(max) has reached the limit value.

Set the ON duty ratio lower.

The heat sink is too small or missing. Provide a heat sink or replace with a larger one.

Reduce the oscillation frequency.

The switching loss is large.

Use a smaller resonating capacitor.

The tightening torque is insufficient.

Tighten at the torque recommended by Shindengen.

Apply silicone grease.

Contact with the heat sink is poor.

Insert a radiation sheet.

Timing for partial resonance is

incorrect.

Adjust the delay setting for partial resonance.

MR4000 Series

generate

excessive heat.

The partial resonance trough is high.

Increase the ON duty ratio.

The oscillation frequency is high.

Reduce the oscillation frequency.

The phase compensation circuit is

inadequate.

Adjust the circuit around the shunt regulator.

Increase the current limiting resistance on the diode side of

the photocoupler.

Intermittent

oscillation occurs

under a light load.

The feedback gain is high.

Connect a resistor in series with the transistor side of the

photocoupler.

6. Supplementary design information

MR4530 Datasheet(PDF) 37 Page - Shindengen Electric Mfg.Co.Ltd

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