Anyone can help me in ADC? Pls...pls..

[shteo83]

I going to use ADC in my digital oscilloscope project but i confuse about the input of ADC. Actually how much the voltage that i can measure, i mean the voltage can enter the ADC. I knew something like Vref = -5v to +5v. But if i want to measure 100v signal, how can i make it? My ADC specification is ADC831, 8 bits, 80MSPS.

 

[Moof]

You have to make an atenuator, like analog osciloscopes. You can make an RC atenuator or just Resistive atenuator.

 

[shameem]

hi,
I think you should scale down your signal by 10 or 15 to get better resolution from the ADC. Like if you want to measure 100V scale down it to 10V. Then set your reference voltage to 5V. The value 7FFF output by ADC will correspond to 0V.The voltages measured above than 7FFF will be positive and the voltages lower than 7FFF will be negative.
Enjoy........

 

[IanP]

You will need Adjustable Attenuator (like in standard oscilloscopes) and/or a DC-XXMHz amplifier ..
Please find below examples of both devices ..
Regards,
IanP