Author Topic: question about resistor across power pins  (Read 787 times)

0 Members and 1 Guest are viewing this topic.

Offline sanmanTopic starter

  • Contributor
  • Posts: 45
  • Country: us
question about resistor across power pins
« 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! 
 

Offline cur8xgo

  • Regular Contributor
  • *
  • Posts: 148
  • Country: us
Re: question about resistor across power pins
« Reply #1 on: June 14, 2019, 03:51:34 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!

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

 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf