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Original question:

MSPM0L1304: Driving resistive-capacitive loads with digital outputs

MSPM0G3507-Q1: instantaneous current limited on GPIO (SPI)

Mat He
Prodigy 80 points

Part Number: MSPM0G3507-Q1

Hey

 we are using the MSPM0G3507-Q to drive a 3D Hall, there is a 1nF capacitor in SPI_CLK and SPI_MOSI and SPI_CS, this is used for ESD protection. it is totally works fine and can meet the Tr and Tf requirement (100ns), but the peak current is much larger than given in DS.

SPI frequency is 300KHz, standard I/O.

The calculated average current Iavg=C*U*F=0.99mA

image.png

assumption:

as stated in the DS, maimum allowed current is 6mA, the dropout voltage is 0.4V, then the resistance of high FET is around 60ohm, so the peak current would be ~3.3/60= ~55mA

Can you tell me whether this usecase can damage the MCU or will decrease the life time

Best regards

 

 

  • 0
    Prodigy 80 points

    regard this topic, can TI put any suggestion?

  • +1 in reply to Mat He
    TI__Mastermind 30386 points

    Hi Mat,

    I think you just use SPI interface to communicate with Hall sensor, correct? Not power for hall sensor, correct?

    If this case, I don't think have some risk here, you don't need calculate the maximum peak current via VCC/Rdson, actually our MSPM0 be able to output PWM means that no any risk here, we can keep GPIO toggle with fast speed within our spec. Even you calculate this current is higher than 20mA, but this current is drive from MCU and very shot time, energy is very low, no damage risk.

    This spec is limit for some continues driver ability for external circuit, not for MSPM0 internal GPIO toggle.

    Thanks!

    Best Regards

    Johnson

  • 0 in reply to Johnson He
    Prodigy 80 points

    Hi Johnson,

     Correct, the SPI is used for communication with 3D Hall, the Hall is powered by +3.3V supply

    Thanks for the clarification, that helps me avoiding additional validation.