How is the solution of converting voltage to frequency and frequency to voltage again implemented in the analog signal isolation solution?

ckf茉莉花

How is the solution of converting voltage to frequency and frequency to voltage again implemented in the analog signal isolation solution? [Copy link]

 

Analog signal isolation has always been a difficult problem. VFC seems to have been used by some people, but I don’t know what circuits people generally use to achieve it, or whether there are any dedicated chips?

maychang

There are special VF and FV conversion chips.

qwqwqw2088

It won’t be the “GP9101” series again.

maychang

AD650.pdf (288.68 KB, downloads: 8)

2019-6-16 17:23 上传

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"Is there any special chip?"

For example, AD650 can realize both VF and FV conversion with high accuracy.

maychang

The chip that can only realize VF conversion is LM331 from TI. Its accuracy is estimated to fully meet your requirements. But this chip cannot realize FV conversion.

LM331 TI.pdf (939.78 KB, downloads: 5)

2019-6-16 21:20 上传

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qiushenghua

maychang posted on 2019-6-16 21:19 The chip that can only realize VF conversion is LM331 from TI. Its accuracy is estimated to fully meet your requirements. But this chip cannot realize FV conversion. ...

Hello, teacher May

I don't know if you have noticed that when the original poster asks questions, he often goes to "dedicated chips".

In fact, many functions can be built with discrete devices, or implemented using MCU+software in combination with hardware.

Why is the OP so obsessed with using a "dedicated chip" to achieve this?

Could it be that the OP has one or several "special chips" that he wants to recommend to everyone, but it is not convenient to promote them directly, so he asks others to recommend these chips by asking questions...

maychang

qiushenghua posted on 2019-6-19 19:52 Hello Teacher May, I wonder if you have noticed that when the host asks questions, he often goes to "dedicated chips". & ...

On the third floor, qwqwqw2088 said "It won't be the "GP9101" series again", which is already a hint.

However, I'm not sure. So I'll reply seriously.

Giorgio

Let’s take a look.

zjqmyron

maychang posted on 2019-6-16 17:25 "Is there any special chip?" For example, AD650 can realize both VF and FV conversion with high accuracy...

I would like to ask, the two chips you gave me look interesting, but now there are some TI ADI isolation amplifiers with higher integration, is this VF FV method less used now? I see that the analog signal isolation acquisition used in the motor is integrated isolation amplifier.

ckf茉莉花

maychang posted on 2019-6-16 17:25 "Is there any special chip?" For example, AD650 can realize both VF and FV conversion with high accuracy...

Thanks for your reply. The cost of VFFV should be higher than that of using isolated op amps directly. Is the reason for choosing it because its accuracy is higher than that of ordinary isolated op amps? Or is this solution no longer used much?

maychang

zjqmyron posted on 2019-6-24 09:08 I would like to ask, the two chips you gave are quite interesting, but now there are also some TI ADI isolated op amps with higher integration, is it now...

“Is this VF FV method less used now?”

It is possible that it is less used now. I am not sure which method is currently popular.

maychang

ckf茉莉花Published on 2019-6-24 09:21 Thank you for your reply. The cost of VFFV should be higher than that of directly using isolated op amps. Is the reason for choosing it because its accuracy is higher than that of ordinary isolated op amps? Also...

More than 10 years ago, the isolation op amp cost several hundred yuan (I used an isolation op amp that cost more than 400 yuan), which was much more expensive than VF->FV. Now, perhaps because of the large production volume, the cost has been reduced, so the VF->FV method is used less.

topwon

I just saw on DIGI-KEY that the unit price of TI's AMC1301 isolation op amp in bulk, including tax, is less than 30 yuan.