Hi
We have unexpected negative output in start-up with SHDNN=Low.
Are there any improvement way?
Rising Negative voltage after positive voltage(OUTP)=5 is required in the circuit.
I think that ADP7182 is good in this case.
https://www.analog.com/jp/products/adp7182.html
Condition table:
| INP | 0 to 18V in 3ms |
| INN | 0 to -18V in 3ms |
| OUTP | 16V setting |
| OUTN | -11V setting |
| SHDNP_bar | Hi = INP |
| SHDNN_bar | Low= GND |
| Load |
no load in this experiment(phenomenon occurs) usual case ±100mA |
In LTSPICE simulation, Negative voltage is GND with SHDNN=GND.
But outn have any negative voltage in start-up.
Below is wave image (measurement result).
At INN=-7V, OUTN rise and down to about -6V(not setting voltage).
Probably, SOA protection operated.
I tried to connect 20kΩ from OUTN to OUTP for SOA current (50uA) but the phenomenon don't improve.
When INN voltage slowly rise(6ms), the phenomenon improve but any INN dip cause OUTN negative voltage(SOA protection?).
SOA protection in Datasheet.
Best regards
Thank you very much.
