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question about resistor across power pins
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sanman:
hello!

I'm working on a board that contains a TI SN74VC8T245. This device uses a VCC-A and VCC-B at pins 1 and 24 respectively.

The manufacturer has bodged a resistor between the two pins, connecting at the bypass capacitors for each pin.

I was just curious why this was being done. Any insight?

Thanks for the help! 
cur8xgo:

--- Quote from: sanman on June 14, 2019, 01:58:56 pm ---hello!

I'm working on a board that contains a TI SN74VC8T245. This device uses a VCC-A and VCC-B at pins 1 and 24 respectively.

The manufacturer has bodged a resistor between the two pins, connecting at the bypass capacitors for each pin.

I was just curious why this was being done. Any insight?

Thanks for the help!

--- End quote ---

Just guessing here:

-That resistor net effect is to keep the two Vcc's near each other
-So if one goes down, the other goes down, if one comes up, the other comes up
-Sort of synchronizing things

Otherwise, one Vcc might be up a long time (relatively speaking) before the other, with undesirable results.

Also notice the "keep ~OE high until vcca and vccb are up"...similar reasoning

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