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I need to use an ISO124P isolation amplifier. The data sheet for the device is here http://www.ti.com/lit/ds/symlink/iso124.pdf

My question is with regards to powering the amplifier. I am really confused with the power supplies. I think I need two different power supplies.

Perhaps a diagram is beter Diagram

In my opinion I should connect:

  • Ground1 to Gnd1
  • +Vcc1 to Vs1
  • -Vcc1 to -Vs1
  • Ground 2 to Gnd 2
  • +Vcc2 to Vs2
  • -Vcc2 to -Vs2

I am correct? Or should I use the diagram of the Figure 22 or Figure 23 of the data sheet for powering the ISO amplifier?

I know this is probably stupid, but I'm pretty new to this stuff.

Any help would be appreciated.

Thanks so much.

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I think I need two different power supplies.

Yes, you need two different (and galvanically isolated) power supplies if you want to maintain proper isolation.

I am correct? Or should I use the diagram of the Figure 22 or Figure 23 of the data sheet for powering the ISO amplifier?

Yes, you are correct AND you can use figure 22 or figure 23's recommendations for isolating power supplies using DC to DC converters.

Just treat both sides as needing a power supply: -

enter image description here

And keep both sides galvanically isolated.

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  • \$\begingroup\$ I have four FA-325 power supplies so I thinking in connecting two in series (I would have then +Vcc1, -Vcc1 and Ground1) and the other two in series too (I would have +Vcc2, -Vcc2 and Ground2).... so If I take a look to the Figure 22 and 23 scheme proposals... I do not know what I should do with Ground1 and Ground2 of the two pairs of FA-235. I believe I should connect Ground1 to Gnd1 and Ground2 to Gnd2 and that would be perfect. But I do not know If I should use scheme Figure 22 or 23 \$\endgroup\$ – Fran Aug 10 '17 at 8:52
  • \$\begingroup\$ Please provide a data sheet link for the power supply and draw a picture of what you mean i.e. I don't understand what you mean when you say "connecting two in series". \$\endgroup\$ – Andy aka Aug 10 '17 at 9:05
  • \$\begingroup\$ This is the data sheet promax.es/downloads/products/esp/FA-325.pdf \$\endgroup\$ – Fran Aug 10 '17 at 9:41
  • \$\begingroup\$ Which scheme I should use? I show them in a picture i.imgur.com/dEfbN9N.png \$\endgroup\$ – Fran Aug 10 '17 at 9:42
  • \$\begingroup\$ If you are using external supplies then there is no need for the DC-DC converters shown in fig 22 and 23. Look at the picture in my answer and use the power supplies to connect to the pins along the bottom edge. \$\endgroup\$ – Andy aka Aug 10 '17 at 9:49
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Figure 22 and 23 are power supply scheme proposals (using another TI component, of course).

If you already have 2 isolated power supplies, then just connect their terminals to your Iso Op Amp they way you stated (Ground1 to GND1 and so on)

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  • \$\begingroup\$ I have four FA-325 power supplies so I thinking in connecting two in series (I would have then +Vcc1, -Vcc1 and Ground1) and the other two in series too (I would have +Vcc2, -Vcc2 and Ground2).... so If I take a look to the Figure 22 and 23 scheme proposals... I do not know what I should do with Ground1 and Ground2 of the two pairs of FA-235. I believe I should connect Ground1 to Gnd1 and Ground2 to Gnd2 and that would be perfect. But I do not know If I should use scheme Figure 22 or 23 \$\endgroup\$ – Fran Aug 10 '17 at 8:52
  • \$\begingroup\$ The link to FA-235 is broken. I'm going to guess that these supplies are isolated, so it should be ok to connect them in series, connect GND1 to Ground1 and GND2 to Ground2. Your configuration look a little bit like Fig23: Your FA-235 will be powered from the mains (analogous to +15V/GND in Fig23), one supply is going to provide ±15V (analogous to ±15V/Input GND) the other power supply, the other ±15V (analogous to ±15V/Output GND) \$\endgroup\$ – HatimB Aug 10 '17 at 9:08
  • \$\begingroup\$ This is the data sheet promax.es/downloads/products/esp/FA-325.pdf \$\endgroup\$ – Fran Aug 10 '17 at 9:41
  • \$\begingroup\$ Which scheme I should use? I show them in a picture i.imgur.com/dEfbN9N.png \$\endgroup\$ – Fran Aug 10 '17 at 9:42
  • \$\begingroup\$ You don't need the DCP011515DB. You already have 2 power supplies. So, scheme 3. \$\endgroup\$ – HatimB Aug 10 '17 at 9:52

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