REF02: output voltage is abnormal

Hello,

Could you please share a schematic of REF02 in your system and an o-scope capture of the output voltage? If REF02 is implemented following datasheet recommendations, this is behavior that should not occur.

Thanks,

Jackson

The circuit and output Voltage(Pin 6 to Pin 4) are as follows.  The +VCC2 is 12VDC. The failed components have been used on the user side for some time.  What are the possible reasons for the phenomenon? Is there any protection method to avoid this exception?

Thanks.

Jiunhung

Hello Jiunhung,

From what you have shown me, I don't see any implementation issue, so it is possible there is something else causing this behavior. Please check the following:

1. Does the input voltage exceed the maximum input voltage of 40V for any period of time, even if that time is brief?

2. Does the load suddenly demand large amounts of current?

3. Is the ambient temperature exceeding the maximum operating temperature of 85°C at any point?

4. Is there any sort of load behavior that is causing the voltage increase?

5. Is there any change in behavior if the load capacitance is changed?

Please let me know if you find anything related to these suggestions or other circuit behaviors.

Thanks,

Jackson

Dear Jackson,

To answer your questions,
1. In the industrial environment, it is difficult to ensure that there will be no high voltage surges. However, other components in this control board are not damaged. The TVS SMAJ15A has been installed at the power(12Vdc) inlet of the control board. Should any other protection method be carried out?
2. I did one test. I connected Pin 6 of REF02 to Pin 4 for ten minutes and then removed the short wire. The REF02 will not be damaged. So I think that overload is not a cause. Is it right?
3. I think the ambient temperature will not exceed 55°C.
Additionally, after I replaced another REF02, the voltage returned to normal. So I think the control board is normal.

Thanks for your help.

Jiunhung