PCM1794A: DEM, pull up, pull down or floating by default?

Andrew Charnley

Part Number: PCM1794A
Other Parts Discussed in Thread: DIR9001,

Scoured the datasheet and nothing to indicate which way the DEM pin is held by default.

It seems like it needs a positive voltage to enable but I'd like to use a weak pull down by default and just need to verify this small query!

over 4 years ago

0 Arash Loloee over 4 years ago

TI__Mastermind 32131 points

Andrew, I checked the user guide and I didn't find any reference to PU or PD for DEM. Usually I just connect the supply and GND pins and measure the needed pin to see if I read H or L.

Can this be an option for you?

Arash

0 Andrew Charnley over 4 years ago in reply to Arash Loloee

Intellectual 640 points

Hi Arash,

I'm not quite there yet, it's actually for inclusion in a prototype board. Normally it'll be controlled by DIR9001 chip directly, but if the chip is missing I'd use a PD to ensure DEM doesn't enable. I can use a strong PD like 1k, in case the PCM1794A has a weak PU. Probably it has neither but I thought it best to ask!

Andrew

0 Arash Loloee over 4 years ago in reply to Andrew Charnley

TI__Mastermind 32131 points

Hi Andrew, since it is not shown in the schematics nor in the data sheet, my assumption would be there is none. You can use a PD as you want to to ensure DEM is not enabled.

Regards,

Arash

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PCM1794A: DEM, pull up, pull down or floating by default?