NX5P3290 output become 0V when OCP happen

[wizleu]

According to the spec, the output voltage shouldn't drop to 0V when the OCP happen. I set the OCP to the 3.3A and drain 4.8A from the output. I saw the output voltage drop to 0V. Is there anything I can check?

[wizleu]

The IC surface temperature is around 60C when the voltage drop happen.

[TomasVaverka]

Hi,

I suppose that the over-temperature protection was activated.

Also make sure that the input voltage remains stable and within the specified range during the overcurrent event. If the input voltage drops significantly, it may affect the output voltage.

BRs, Tomas

[wizleu]

Hi Tomas, 

thanks for the reply.  Here is the waveform(VSYS_5V=VIN,  5V_OUT= VBUS)  and the circuitry. It seems that our input voltage didn't enter the UVLO range when the OCP happen.

[TomasVaverka]

Hi,

Thanks for sharing additional information including the schematic and waveform.

Based on that and after my discission with our application engineer, it is normally OCP function, the NX5P3290 controls the MOSFET Rds to limit current under OCP happen status.

You can assume Vin=5V if current = 3A Rds=35 mOhm(type) Vout=4.895, if Vin=5V current=4.8A (trigger OCP and not trigger SCP/OTP) Rds will rising Vout will drop until Vout=0V.

BRs, Tomas

[wizleu]

Could you clarify the OCP behavior on Vout when I draining 4.8A? Is there any solution to increase the voltage drop duration from 5V to 2V when we increase current drain to 4.8A?  We had a reqiument to pass the MFi certification on OCP. 

thanks

[TomasVaverka]

Hi,

Please see below the answer from our application engineer.

I think it’s not normally scenario for this chip design goal. I think 4.8A is not normal user case, so the chip need to work OCP function to protect it.

We don’t have method to stop it…

BRs, Tomas