Isolation recommendation

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#1
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Dear all
I want to know how would you isolate ade7753 from your avr? what is the minimum cost recommendation. I could use 6n137 device successfully (spi clk ~ 8khz) but was unable to achieve the same with tlp521.do you know what might have been wrong? Any ideas are welcome!

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Minimum cost? Have the avr on the live side and isolate uart serial comms using optos or isolators from nve or analog devices.

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I want to put ade7753 in isolation. I could get answers from it using 6n137 but I do not know why I cannot get the same result with TLP521.and I mean the lowest cost isolation device or…!?

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Like kartman I would put the AVR on the live side, and perhaps a pulse transfo for data and power to the "live" side.

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But would you need two power supplies then, one for the live meter chip and one for the isolated AVR?

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Guys do you know what caused the tlp521 to not functioning correctly?

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Ali,

The tlp521 looks like a much much slower opto then the 6n137.

Have you checked the serial speed from the meter ic?

oddbudman

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Quote:
Have you checked the serial speed from the meter ic?

Yes i just slow it down to 8khz.and i think i just touched the chip and it's dead...it's the third device. Do you think my fingers might kill them!!!

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From the TLP521 datasheet it can be seen that it should
be possible to achieve switching times below 25us
with high enough diode current and low enough
collector resistance. So it should be possible
to get 19200 bit/sec without problem. To
get much higher (115200) will probably be
impossible.

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Also have you managed the different output circuit?
6N137 has TTL output circuit,TLP521 is a photo transistor...

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I have used the HCPL060 for a 20MHz SPI link.

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I use 7414 for signal conditioning and could use tlp521 too!

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