INA125 and EasyPic v7 A/D VRef+/VRef- direct connection for A/D conversion?

[strasni_betmen]

INA125 and EasyPic v7 ADC VRef+/-

Hi all,

For A/D conversion I'm planning to connect INA125 5V precision voltage reference to VRef+ on the EasyPic v7(onboard is PIC18F45K22) board and GND to VRef-. INA125 setup and EasyPic v7 board have each own power supply. There's a circuit from INA125 datasheet that I intend to connect to EasyPic board.

I'm not so experienced in electronics so I was wondering if I can connect INA125 5V/GND -> EasyPic VRef+/VRef-board directly?


Kind regards

 

[hemnath]

I think, you should short pin 4 and pin 15. So that you can get precision +5V output.
Check the output voltage before connecting to Vref+ of uC. If the voltage is stable, then connect to uC.

Best wishes

 

[strasni_betmen]

I have 2 load cell parts, one for 1kg and the other for 200kg. The 1kg load cell works good with pins 4&15 shorted, but the 200kg load cell gets the precision reference to drop a little. That is the reason I use attached scheme in which they propose the use of TIP29C if the precision reference voltage drops because of current drain. I just followed instructions and it worked.

I have read something about keeping ADC input imedance below 2k, but could not understand it, so I was hoping somebody could give me some advice on connecting INA125 precision voltage reference with PIC VRef+/- pins for the goal of getting ratiometric configuration and stability on ADC readings?

Anybody have a sugesstion?

King regards