MC33771C OC Fault detection speed

[JuanDavid]

Hello,

I'm running tests with this BCC and in the case of the OC detection the timing I see from the datasheet is different from what I'm getting.

I'm reading around 300uS from the current reaching the OC limit to the Fault Pin being UP.

ADC resolution is 16 bit.

BCC is in continuous measurement mode.

According to the datasheet the time it takes for ADC2 to perform the current reading is 40uS.

What am I missing?

Thank you.

[JuanDavid]

Thank you Tomas.

As you pointe out probably the delay is cause by my filter which is the same recommended in the datasheet..

Also I'd like to ask about that parameter from the datasheet. It specifies that those 56us happen in normal mode but the overcurrent fault happens ONLY in sleep mode. Does tfault varies in that case?

Thank you.

[TomasVaverka]

Hello Juan,

What is the filter that you have on the current sense line? What is its time constant?

Could you please share a scope plot illustrating your measurements?

As shown in the datasheet, the fault pin should be activated within 56us from the fault event.

Best regards,

Tomas