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INA241A: Request for pin-to-pin replacement part

Anubhav Anubhav
Prodigy 20 points

Part Number: INA241A
Other Parts Discussed in Thread: INA241B,

Part No: INA241A3IDDFR
This is the existing part which is not available to procure now.
I need pin-to-pin replacement part with same specifications.

I found this part no. INA241B3IDDFR

However, there is a deviation as below (as shown in datasheet):
Accuracy:– Gain error (maximum) • Version A: ±0.01%, ±1ppm/°C drift • Version B: ±0.1%, ±5ppm/°C drift– Offset voltage (maximum) • Version A: ±10µV, ±0.1µV/°C drift • Version B: ±150µV, ±0.5µV/°C drift 

  • 0
    TI__Mastermind 20060 points

    Hello, 

    Thank you for your post. 

    Bottom line: The INA241B3IDDFR is pin-to-pin compatible, but carries significantly degraded accuracy — whether it's an acceptable replacement depends entirely on your application's precision requirements.

    White check mark Pin-to-Pin Compatibility: Confirmed

    The INA241A and INA241B families share identical package options, including the DDF (SOT-23, 8-pin) package used by both parts in question [1]. Both the A3 and B3 variants correspond to the same 50 V/V gain [1], meaning no schematic or layout changes are required. You can drop the B3 in physically without modification.

    Warning️ Accuracy Deviation: A Direct Comparison

    The performance gap between the two versions is substantial across every accuracy parameter:

    Parameter

    INA241A3 (Existing)

    INA241B3 (Proposed)

    Degradation Factor

    Gain Error (Max)

    ±0.01%

    ±0.1%

    10× worse [2]

    Gain Error Drift (Max)

    ±1 ppm/°C

    ±5 ppm/°C

    5× worse [2]

    Offset Voltage (Max)

    ±10 µV

    ±150 µV

    15× worse [3]

    Offset Voltage Drift (Max)

    ±0.1 µV/°C

    ±0.5 µV/°C

    5× worse [3]

    Reference Voltage Rejection (Max)

    ±1.5 µV/V

    ±20 µV/V

    13× worse [2]

    Reference Divider Accuracy (Max)

    ±0.01%

    ±0.15%

    15× worse [2]

    Version A is explicitly the high-precision variant of this family; Version B is a lower-precision offering [1]. These are not minor datasheet footnote differences — they represent a fundamental accuracy class change.

    Mag How to Assess If the B Version Is Acceptable

    The substitution may be viable or problematic depending on your system context:

    The B version is likely acceptable if:

    • You are measuring large currents where the ±150 µV offset is negligible relative to your sense voltage (V_SENSE)
    • Your system has calibration or trimming routines that can compensate for the higher offset at a known temperature
    • Your application operates over a narrow temperature range, limiting the impact of the higher drift coefficients
    • Your downstream ADC or controller has a coarse measurement resolution that already exceeds the B version's error margins

    The B version is likely NOT acceptable if:

    • You are measuring small currents with low V_SENSE levels, where a ±150 µV offset introduces significant percentage error
    • High precision over temperature is required (e.g., across the full −40°C to +125°C operating range) [3]
    • Your system has a tight error budget that was designed around the A version's ±0.01% gain error
    • No software or hardware calibration is available to compensate for the accuracy loss

    Pushpin Recommendation

    If your application can tolerate the reduced accuracy, the INA241B3IDDFR is a valid drop-in replacement — same pinout, same gain, same package [1]. However, it is not a specification-equivalent replacement. You should formally evaluate the impact of:

    1. The 15× increase in offset voltage against your minimum expected V_SENSE
    2. The 10× increase in gain error against your system's total error budget
    3. The higher drift coefficients if your design operates across a wide temperature range

    If precision is non-negotiable, it's worth investigating whether the INA241A3IDDFR is temporarily out of stock versus discontinued, or exploring alternative high-accuracy current sense amplifiers from TI's portfolio that meet the original A-version specifications.

    Citations

    1. INA241 Datasheet (SBOSA30D) – Texas Instruments
    2. INA241 Datasheet (SBOSA30D) – Electrical Specifications, Page 6
    3. INA241 Datasheet (SBOSA30D) – Electrical Specifications, Page 5

    I hope this helps, 

    Joe