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INA228: ALERT pin trigger bidirectional

Bjoern Stache
Prodigy 85 points

Part Number: INA228

Can the INA228 measure bidirectional current via i2c, and can the ALERT pin trigger on both positive and negative overcurrent events across the shunt. (bidirectional overcurrent trigger)

  • 0
    TI__Mastermind 30495 points

    Hello Bjoern,

    Yes — the INA228 supports both bidirectional current measurement via I2C and bidirectional overcurrent alerting.

    Bidirectional Current Measurement

    The INA228's shunt voltage register (VSHUNT) uses two's complement encoding and supports a full-scale differential input of ±163.84 mV or ±40.96 mV depending on the ADCRANGE configuration bit.

    Bidirectional Overcurrent Alert (ALERT Pin)

    The ALERT pin can trigger on overcurrent in both directions using two independent threshold registers:

    Direction

    Threshold Register

    Status Bit

    Default (disabled)

    Positive overcurrent

    SOVL (Shunt Over Voltage Limit)

    SHNTOL

    0x7FFF

    Negative overcurrent

    SUVL (Shunt Under Voltage Limit)

    SHNTUL

    0x8000

    Both thresholds use two's complement values, so you set SOVL to your positive current limit and SUVL to your negative current limit independently. Both can be active simultaneously — the INA228 supports multiple alerts with both high and low limits at the same time.

    How to Configure

    1. Write your positive overcurrent threshold to the SOVL register (address 0Ch)
    2. Write your negative overcurrent threshold to the SUVL register (address 0Dh)
    3. Read the DIAG_ALRT register (address 0Bh) via I2C to determine which event triggered the ALERT pin

    By default, thresholds are set to their extreme values (effectively disabled). Setting them to any other value enables the alert — the measured value must cross the threshold to trigger.

    Regards,

    Mitch