Author Topic: Maximum current on D0-D7, high level  (Read 3995 times)

alberich

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Maximum current on D0-D7, high level
« on: February 21, 2014, 12:03:20 pm »
Hello everybody.

In the book "Parallel Port Complete", I have read (pages 106 to 109) that 2 "Levels" existed : the first one with only 0.32mA of output current guaranteed, the second with about 12mA. In a former topic (Dec 2010) I have read that nothing ensures that the chip delivers more than the minimum guaranteed.

The only problem is that chip and card manufacturers write in their specs many interesting things, like port mode (SPP etc), maximum bandwith, EMC and RoHS data, but NEVER the "level" or the maximum current !

My card is a PCI model (not an old ISA type ! ), with a chip made by SUNIX, labelled SUN1989. I tried to contact a SUNIX distributor, but without "too much hope". The card "survived" a current of about 1mA (optocouplers TLP621 switching MOS inputs), but not in continuous mode.

1mA would be enough for my application, but I don't know if the card will not get damaged after a while. On the other side, I think that the minimum specs of Level 1 are obsolete, except perhaps for devices in laptops (does any model still have a parallel port ?  :-[ ) for energy-saving purposes.  

If anybody knows more about that chip, thanks for any answer ...
« Last Edit: February 21, 2014, 01:37:20 pm by alberich »

Jan Axelson

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Re: Maximum current on D0-D7, high level
« Reply #1 on: February 21, 2014, 02:35:58 pm »
The Level 2 ports existed when I wrote the book in 1996, so the Level 1 ports are likely obsolete though I will admit that I haven't kept up on this issue.

You can test by putting a 1-mA load on low and high outputs and measuring the voltage. If you get valid logic levels, you're OK.

alberich

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Re: Maximum current on D0-D7, high level
« Reply #2 on: February 21, 2014, 05:10:57 pm »
Thank You for that idea. I will connect my loads to the outputs, switch them to "high" and then measure the output voltage to see if it further more than the "minimum" of 2.4v ...