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INA228: Shunt resistor package selection

melissaw
Genius 15520 points
Part Number: INA228

Tool/software:

Hello,

With our INA228, we’ve been using shunt resistors with 4 pins designed for kelvin sensing like RES SMD 1 OHM 1/2W 2516 WIDE.

Example Y08501R00000F9W - $12.82 each

What is the consequence of using a wide body, 2-pin resistor like RES SMD 1 OHM 1/2W 1206 WIDE?

Example RCA06121R00FKEALS - $0.32 each

We could still have 4 separate pads where 2 can carry current and 2 measure voltage drop…

Or if not necessary, we could use 2 pads with low impedance traces for current and high impedance traces for voltage drop measurement.

There appears to be more availability and lower cost for the 2-pad resistors. Thanks.

  • 0
    Guru 267600 points

    The contacts and the pads themselves have a certain resistance, and the current through them results in a voltage drop.

    It is certainly possible to have four traces going to two pads. You'd have to estimate what the voltage drop over the pads is. (1 Ω is not very small; it would probably negligible.)

  • 0 in reply to Clemens Ladisch
    TI__Mastermind 29490 points

    Thanks Clemens,

    Using the wide body resistors 1206 instead of 0612 allows for larger pads and reduced IR drop.

    It sounds like there is no requirement or justification to use 4-pad kelvin current sense resistors over 2 pad wide body, correct?

    -Mark

  • 0 in reply to Mark M
    TI__Mastermind 20415 points

    Hey Mark,

    In general, it would be fine to use the 2 pad wide body. The ideal way to connect to the 2 pad resistor would be with kelvin connections in the center of the pads, similar to this:

    Regards,

    Mitch