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AD5272BRMZ-50 tolerance 15%

Thread Summary

The user inquired about a 15% normal mode tolerance in the AD5272 datasheet, noting one of three units showed a significantly larger output waveform. The final answer clarified that the 15% tolerance applies outside Performance (R-Perf) Mode. The user confirmed the issue was resolved after testing with a fixed resistor and swapping the potentiometers, suggesting the problem was related to the specific AD5272 unit or configuration.
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Category: Hardware
Product Number: AD5272

Could someone please elaborate on what 15% normal mode tolerance implies in below listed datasheet section.

We have one of the three units showing significantly larger OUT waveform than what would be consistent with 1% components and 1% digipot value.  We have the digipots in each unit configured identically near mid point to achieve what we interpret as 1% value based on your tables for 1% codes. 

Inputs (IN) to op-amp on each unit is very near identical but OUT on one of the units is noticeably larger, implying gain is larger.   Digipots A and W terminals are connected in inverting op-amp as shown below.

Moreover, when i replace the digipot with a fixed 25.5k resistor, I get consistent output across all three units.

Is this expected behavior?

Parents
  • Hi  ,
    The 15% tolerance applies when you're not using the Performance (R-Perf) Mode.
    Have you tried to swap one of the AD5272 units with expected output to the one with significantly larger output?
    Since it is working as expected with 25.5k fixed resistor, it may be a code/SPI issue, but the other 2 units seems functioning within your intentions.
    If swapping with another AD5272 works, then we can isolate the problem (assuming the other components across 3 units are the same)

Reply
  • Hi  ,
    The 15% tolerance applies when you're not using the Performance (R-Perf) Mode.
    Have you tried to swap one of the AD5272 units with expected output to the one with significantly larger output?
    Since it is working as expected with 25.5k fixed resistor, it may be a code/SPI issue, but the other 2 units seems functioning within your intentions.
    If swapping with another AD5272 works, then we can isolate the problem (assuming the other components across 3 units are the same)

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