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TDA4VM-Q1: Pin naming convention: What is the meaning of signals with names ending in 'z'?

John Weber
Intellectual 511 points
Part Number: TDA4VM-Q1
Other Parts Discussed in Thread: SK-TDA4VM, TDA4VM

I had originally assumed that signals with names ending in 'z' were open-drain/open-collector signals (and thus usually are active-low signals).

However, I've noticed that many signals such as MCU_PORz_OUT, PORz_OUT, RESETSTATz, and MCU_RESETSTATz are pulled low on the SK-TDA4VM. This means that they must be actively driven high, which means they aren't open-drain signals.

So, what is the significance of the "z" in the signal name?

Thanks!

  • +1
    TI__Guru 52335 points

    'z' is a common label in the industry that means active low.  It is similar to 'n' or 'b'....all typically mean signal is active low.

  • 0 in reply to Robert Eschler
    Intellectual 511 points

    Thanks Robert. The 'n' suffix is also used to indicate active low on TDA4VM pin names, so wasn't sure if the "z" meant open-drain in addition to active low. It sounds like they just mean the same thing.

    The reason I ask is because in my review of our design, MCU_PORz is pulled low by both a CPLD and the PMIC.  That is a 1.8V signal, but the CPLD I/O voltage is 3.3V (as it is on the SK-TDA4VM). In theory this is fine as long as the CPLD is driving this as an open-drain output.