Hi,
We have a question from Customer.
Regarding the reset signal of the ADAU1452, are there any regulations regarding the waveform rounding for the rising/falling edges?
We checked the data sheet, but there seems to be no mention of it.
Sorry for the sudden contact, but could you please answer by January 26th?
Best regards,
Hello HTCV3,
This is a combination of a couple of specifications and one aspect that we really cannot define easily.
The first is the reset pulse duration itself.
The pins must be below the input-low trigger point for at least 10ns.
This 10ns is measured from the trigger points of what constitutes a low and a high for digital pins.
You will find that info here:
So you need to be below 0.3x IOVDD for at least 10ns before you go back up to 0.7 x IOVDD where it will register as a high.
Now these specs are to define where the signal will absolutely be called a low or a high. The actual voltage where this happens will differ from part to part and over temperatures.
There is going to be a little hysteresis and we really do not characterize that. Also, if the slope is really slow then noise can cause the reset to trigger then go out of reset then back into reset etc., if the noise is right on the edge of the thresholds. This would be very difficult to actually get it to do this so I really do not see this as a problem. A slightly rounded off slow edge should not be a problem as long as it remains low for 10ns.
By the way, I strongly recommend using a reset generator in your design if you have resets coming from different places or things like manual pushbuttons that can really bounce a lot!!! In designs I have done I have found this to really prevent flakiness in the future operation.
Something like the ADM811/812. This will ensure a clean reset.
Dave T
