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INA226: –48-V Telecom Current, Voltage, and Power Sense With Isolation Reference Design

Part Number: INA226
Other Parts Discussed in Thread: TIDA-00313,

Hi team,
We have designed an isolated voltage monitoring system as per TIDA-00313. Below I add a few doubts about this.
1)Do we require to connect +volt external power supply for INA226 Vs and ISO VCC1?. (Both VS and Vcc we connected to 4.7V Zener, will create a potential 43.3V difference between -48 and GND, Will this be enough for Vs ?)
2) The -VIN, +VIN, and Vbus Bottom resistor connections are Different in the TIDA design guide(fig2) and TIDA Schematic. which one is suitable for -48V.
3)Please find the attached Diagram for Review

  • Hello valued engineer,

    I am looking over your question and will reply back by end of the day.



  • Hello,

    1. It is recommended to connect Vs and VCC1 of the isolated to same voltage. 48-43.3 = 4.7V and this is a valid supply voltage for INA226.
    2. The resistor divider circuit for VBUS pin can be connected to the -48V rail (IN+) or IN- pin. Both are valid conditions since they are essentially the same voltage, the only difference being of course the shunt voltage drop. If you want to sense this leakage current through the resistor divider, then connect it to IN- side of shunt so leakage current flows through shunt and is included in the total load current sense. If you don’t want to sense this leakage current, then connect it to IN+ side of shunt (the -48V rail) so it does not flow through shunt resistor.
    3. The schematic is fine with just one error. You should not pull up or pull down the address pins (A0 and A1) with any resistance at all. They should be 0-Ohm resistors or direct trace connections.

    Hope this helps.



  • Hello, Peter lliya,

    Thank you for your valuable reply

  • No problem Anoop.