Hi ADI folk,
I am a bit confused about the behaviour of MISO in high impedance state.
Following the ADE78xxA datasheet, it goes into high impedance state while SS is not active.
When looking at the ADE7878A eval board schematic, there is no external pullup resistor on the MISO line between the ADE7878A MISO pin and the input pin of the ADUM3401 data isolator.
We are using ADE7854A for a while now, where the MISO pin is also directly connected to a logic input gate, without an external pullup resistor, and it is working well.
Looking at the oscilloscope, the signal level of MISO behaves as there is an internal pullup existing, but in the datasheet I cannot find anything about MISO behaviour in high impedance state.
But if there is no internal pullup, why and how is the signal level of MISO so clearly defined during high impedance state, since I would have to expect it to be floating?
Could you please confirm whether there is an internal pullup or not? And if there is one, which value is it about?
Many thanks for your response!
Markus
