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TS5A4594: Query regarding internal resistors

Vijetha HN
Intellectual 705 points
Part Number: TS5A4594


Hi,

We are using TS5A4594DBVR in our design as per the attachjed image. 

Here the purpose of TS5A4594DBVR is to connect or disconnect the 665 OHM resistir between pin 2 and 3 of Instrumentation amplifier to select Gain =1 or 10 for the Instrumentation amplifier(IA).

When we tested this circuit, we observed that the IA was behaving weirdly. The output of IA was not coming as expectected. But when we removed TS5A4594DBVR and 665 OHM, then the IA was functioning as expected.

When we just removed 665 OHM and kept TS5A4594DBVR in the circuit, still the functionality was not correct. Only when we remove TS5A4594DBVR and 665 OHM, the functionality of IA was correct.

So we just checked the resistances of pins of IC TS5A4594DBVR w.r.t Ground. We observed nearly 50K OHM from pin NO to ground. Is this resistance expected? We strongly believe this resistance is causing the treouble in our circuit. Please let us know your inputs on this.

Regards,

Vijetha HN

  • 0
    Guru 318300 points

    The TS5A4594 is damaged.

    What are the voltage ranges at the amplifier's inputs? Voltages below GND or above V+ will damage the switch.

  • 0 in reply to Clemens Ladisch
    Intellectual 705 points

    Max voltages at the input of Amplifier was in the range of 0V to 3.2V. Will this damage the IC?

    Infact, when we send 0V at the input of Amplifier, we observed nearly -2V at the ammplifier output. That -ve offset continued for all the voltages till 3.2V input.

    When we removed the Analog switch, then it works as expected (i.e 0V to 3.2V at the amplifer input was reflecting at amplifier output).

  • 0 in reply to Vijetha HN
    Guru 318300 points

    When the voltages at the COM/NO pins are below 5 V, then your circuit is OK.

    The TS5A4594 is damaged, but I do not know the cause. (One possibility is ESD.)

    Try replacing the chip. Does this happen with one board, or with all boards?