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TCA9555: TCA9555RTWR power consumption issue

Wu MingWei
Prodigy 50 points
Part Number: TCA9555
Other Parts Discussed in Thread: TCA9535

Hi Sir,

We use the TCA9555RTWR to extend GPIO numbers, but the power consumption can't meet the spec in datasheet.

In datasheet the power consumption at operating mode is 30uA(max), but in our circuit it consume around 0.4mA.

Even we remove the component that connection after the TCA9555RTWR, the power consumption is the same.

So we need your help to clarify why the TCA9555RTWR power consumption can't meet the spec.

Thanks

[TCA9555RTWR power consumption data]

[Application circuit]

[TCA9555RTWR setting]

P0~P17

Setting @ Sleep Mode

HALL_DET

Output Low

IRCUT_SW

Output Low

LED_R

Output Low

LED_G

Output Low

DC_OK#

Output High

LED_B

Output Low

DDR_RST_EN

Output Low

CHRG_OK#

Output High

PWR_PSEQ1

Output Low

PWR_PSEQ2

Output Low

PWR_PSEQ4

Output Low

PWR_PSEQ3

Output Low

PWR_POR_L_3V3

Output High

NRST

Output High

CE

Output High

TP43

Output Low
  • 0
    TI__Mastermind 49040 points

    I believe you're misunderstanding what operating mode is. Operating mode involves the SCL/SDA pins switching and based on the test conditions state the GPIOs are all set to INPUTs and tied  to GND. 

    My guess is you're measuring the stand by current instead since you're p-ports are set to an output and likely aren't switching the SDA/SCL lines during your measurements. In the standby case, the datasheet specs that the supply current is lowest when the device's inputs are biased to a HIGH state. 

    -Bobby

  • 0 in reply to BOBBY
    Prodigy 50 points

    Thanks Bobby,

    Confirmed with you about  the IO expander setting to input then it will pulled high via internal resistor directly or not.

    Beacuse when we setting all the GPIO as input, it will turned the NMOS ON and turned the LED ON.

    Another question is TCA9555RTWR can setting as input low or not ? if yes, it's mean the power consumption will keep in mA grade ?

    Thanks.

     

  • 0 in reply to Wu MingWei
    TI__Mastermind 49040 points
    Wu MingWei said:
    Confirmed with you about  the IO expander setting to input then it will pulled high via internal resistor directly or not.

    Yes, since the device has internal pull ups on the p-ports so the input will detect it as a logic high unless there are external pull downs to drive the logic level low.

    Wu MingWei said:
    Another question is TCA9555RTWR can setting as input low or not ? if yes, it's mean the power consumption will keep in mA grade ?

    No, not without populating an external pull down resistor but this would cause additional current consumption since you would be sinking the current through the internal pull up resistor. If current consumption is a concern, you could instead use TCA9535 and an external pull down resistor instead. 

    -Bobby