Author Topic: [Help] Suggest opamp to shift and gain 50x of AC signal to ADC?  (Read 87 times)

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Offline nhn

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[Help] Suggest opamp to shift and gain 50x of AC signal to ADC?
« on: September 22, 2019, 02:20:26 pm »
Hi

I'm new here. Sorry if my English is not good.
I has a simple knowledge about Electric. I try to design my own energy meter using voltage transfomer, current transformer and STM32's ADC. To read AC Voltage I use current type transformer, output swing from -0.033V to 0.033V. I searched and found that I can use differential amplifier with Voltage Ref is 1.65V, below is my schematic. I run simulator and it's working. But I don't know which opamp is good for my case, so I post here looking for any suggestions, dual opamp is better, one for buffer, one for shift and gain. Source voltage is AC 230, 50Hz. SDADC run as 6 MHz, 300ksps.

Thank very much

 

Online rstofer

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Re: [Help] Suggest opamp to shift and gain 50x of AC signal to ADC?
« Reply #1 on: September 22, 2019, 02:42:20 pm »
Figure 4-7 in "Op Amps For Everyone" - look at curve for TLV2472

https://web.mit.edu/6.101/www/reference/op_amps_everyone.pdf

The TLV2472 is a single supply rail-to-rail op amp with output characteristics that get very close to the rails.  The TLV2472 is a dual op amp.  It is also available as a single and quad.  You should still design the circuit to stay away from the rails.  Check the datasheet.

Rail-to-rail is a marketing term, not an engineering reality.  If you look at the output voltage (high and low), you will see that it only comes within 150 mV.

http://www.ti.com/lit/ds/symlink/tlv2472.pdf

 


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