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[Help] Suggest opamp to shift and gain 50x of AC signal to ADC?
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nhn:
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
rstofer:
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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