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TCA9555: TCA9555 high quiescent current in standby mode low inputs

Julie Moreau
Prodigy 30 points
Part Number: TCA9555

Tool/software:

Hello,

From the TCA9555's datasheet, for low inputs, the quiescent current in standby mode is 1.5mA max while it is 40µA max for operating mode. The quiescent current is then much higher in standby mode than in operating mode. It doesn't seem consistent, especially as the datasheet says “Low Standby-Current Consumption of 3.5 μA Maximum” on the first page. Is this an error on the datasheet ? Is it 1.5µA instead of 1.5mA?

Best regards

  • 0
    TI__Mastermind 48268 points

    Hi Julie,

    This is due to the internal 100k pull-up resistors that cannot be disabled within the IO expander. This is why there is a difference between HIGH and LOW inputs. LOW inputs will cause current to flow from VCC through the internal 100k pull-up resistor to GND increasing ICC in standby mode. 

    In operating mode, although the IO's are configured as inputs, they are pulled high by internal 100k pull-ups reducing overall ICC. Only SCL is being toggled on the I2C side. 

    The additional current by toggling SCL in operating mode should be compared to standby mode when inputs are pulled HIGH. 

    Regards,

    Tyler