DPA424 lock out?
Posted by: choede
on
We currently experience a new problem with the DPA424SN (3740,44587A) & (3741,45808A).
When we insert a board to the 48V power it starts up. When we repeat this within 2 seconds (disconnect and connect to the power) the DPA424 ends up in a situation where the drain is not switching and the Control is a DC voltage of 6.58V. This situation will remain that way and the switcher will not start while power is applied. When we wait longer with reconnecting, like 5 seconds it will start and when we manually shortcut the control to the ground it also starts. It looks like the control voltage has to be below a certain value to restart.
We never had this problem before on other DPA424A, we can also fix this problem by replacing a DPA424 from the same roll with a new one. Currently we have 10 DPA424A with this behavior.
Question : Are we doing something wrong in the schematic or is there something wrong in the DPA424?
Thanks& Regards,
Chris
Files
첨부 파일 | 파일 크기 |
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DPA424 schematic.pdf | 26.5 KB |
Do you have a waveform of the voltage on the control pin? I want to see if at the end of the 2 s the Control pin dischgarges to below 4.8 V.
Also, the standard value of control pin cap for DPA Switch is 47 uF or a 68 uF. I see you are using 2 47uF caps in parallel.
I am not aware of any latches that would be triggered by the condition you describe.