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ISO122 Input and Output Voltage Range

Question about the INPUT and OUTPUT voltage range on the specifications. It mentions MIN +/-10V. Does this cover an input from 0 to +2.2Vdc?

5 Replies

  • Jun,

    Yes, the ISO122 can be used for 0V to 2.2V signals. Minimum power supply for good accuracy over this signal range would be -5V and +7.5V. This device requires a negative power supply for proper operation.

    Regards, Bruce.

  • In reply to Bruce Trump:

    Bruce,

    For a 0-2.2Vdc input, will I get an accurate output if I use a +/-5V supply for both the input and ouput section?

    Regards, Jun

  • In reply to Jun Adriano:

    Jun,

    The ISO122 is specified and tested for accurate output signals of +/-10V on +/-15V power supplies. This implies that the output voltage can accurately swing within 5V of each rail. With +/-5V supplies, this leaves no margin for assured output voltage swing. The typical output capability is +/-12.5V on +/-15V supplies or 2.5V from the rails. So on +/-5V supplies you are likely to get approximately +/-2.5V output swing. This behavior is not assured or tested and accuracy will likely be degraded somewhat in this region of operation. Furthermore, there may be greater temperature sensitivities in this region and the maximum available output swing may change with temperature.

    Regards, Bruce.

  • In reply to Bruce Trump:

    Bruce,

    Thanks for the explanation. My problem is, I am limited with the supply voltages on both the input and the output and I need my input to output to be accurate. Then, could I just follow the voltage supplies similar to figure 10 of the datasheet, that is, +/-5V at the input and perhaps +/-10V at the output and still get a MAX +/-0.5% gain error? Relating to accuracy, does TI have an isolation amplifier that is 0.1% accurate?

    Regards, Jun.

  • In reply to Jun Adriano:

    Jun,

    You are correct, a +/-5V supply on the input side is adequate. While it is not production tested under this condition, gain accuracy is unlikely to be greatly affected.

    I am not aware of any TI isolation amplifier with a gain accuracy of 0.1%.

    Regards, Bruce