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I am working on a project that uses the Microchip HV5623K7-G Serial-to-Parallel converter. As part of the design process I need to determine what would happen if the board I am designing is plugged in backwards. The details for this are not important for the question, however. My question is in regards to the "Data Out" of the device. I see in the datasheet (http://ww1.microchip.com/downloads/en/DeviceDoc/hv5623.pdf) that the Data Out is set up like this:

Data Out Internal Schematic

However, I do not have any information about the output FETs, and I can't find anything in the datasheet. On my board, if plugged in backwards the worst case scenario would be that I would have an output of another board trying to drive the Data Output of the HV5623. If this happens, I need to know how much damage it would do, and how to prevent it. I don't know the maximum current or reverse voltage, both of which would help. If I can find these, I will be able to prepare for the worst case. Are these values available anywhere? I can't seem to find a simple "Tech Support" email address on the Microchip website, so contacting them would be difficult for me.

So, to be clear, my questions are as follows:

  • What is the maximum reverse current the Data Output of the HV5623 can stand (current flowing INTO the output) before being damaged
  • What is the maximum reverse breakdown voltage of the Data Output on the HV5623?

The most important one would be the first--the maximum reverse current. The voltage should be around 5V so I'm not too worried about that.

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Well, it's specified at +/-10mA so that seems fairly safe. If you add a series resistor of 510 ohms to each data output then no more than 10mA can flow if the voltage difference is limited to 5V. That will impact the speed somewhat, but perhaps that's not an issue for your application.

You could also add a Schottky diode to prevent an external negative voltage from driving it negative by more than the 500mV specified in absolute maximum ratings (if that's a possible condition).

Microchip has forums for this kind of tech support. You may even find some of the same people there who are here.

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  • \$\begingroup\$ Ah, I could not seem to find any current ratings for the DATA OUT pin. I see it now. The speed of the signal really can't be affected much, but I may be able to take the resistor route. As for the Schottky diode, I don't think that would be an option in this case. I tried going to the Microchip forums and attempted to sign up for an account but every time I submitted the form it would just pop it up again (there were no errors on it, it just wouldn't accept it). \$\endgroup\$ – DerStrom8 Jun 25 '15 at 14:23

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