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TSM102: Voltage offset at the op-amp TSM102IPWR

Part Number: TSM102

I'm using this for current sensing.

I have an amplifier stage with a gain of ten.  It is powered from 5V (single supply).  The output has a surprsingly output for zero input.  Over 100mV.

When I measure the offset voltage (between the + and - inputs) I see 9.75mV.

The quoted input offset voltage is 6.5mV over the whole temperature range!

Moreover this problem is general, every unit has shown around 10mV of offset.

Is the data sheet wrong?

  • Robert,

    Were both inputs zero volts or were both input the same voltage? What was that voltage?
  • Hi Ronald,

    Yes both inputs were at 0V.

    The other op-amp wired as a voltage follower and it too has an offset voltage of about 10mV, the input voltage is 120mV.

    Rob

  • Robert,

    If the output is not loaded beyond what the schematic shows, then the output current is about 10uA out of the TSM102 (-10uA on chart).

    At this load current the output can get very close to ground.

    This is VOL vs. IOL for an input voltage of 9.75mV on inverting input for a sample device. 

    Here is the same chart expanded to higher IOL current.

    The data sheet VOL occurs near 250uA. 

    Therefore, I would not expect a >100mV output. Unless there is another output load that requires milliamps of current.

    How many samples have this behaviour? What is the failure rate? Is this a new or old design?