This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

MSP430FR69721: Digital output minimum value under specific Vcc condition

Part Number: MSP430FR69721

Hello,

There is Table 5-12 lists the characteristics of the digital outputs in datasheet.
My customer would like to know digital output minimum value (VOH) under Vcc=2.4V condition.
Is the spec of MIN same as (Vcc - 0.6)?
or is there other value?

Regards,

  • Hello,

    the Table 5-12 is basically reflecting the RDSon characteristic of the GPIOs in dependency of the supply voltage. The performance is decreasing with supply voltage. This is e.g. visible, when looking at the specification for 2.2V where we specify for output Vohmax -3mA but with 3.0V -6mA. This means the RDSon is with lower supply voltage decreasing.

    Unfortunately we do not have values for all supply voltage levels, but you can assume the 2.4V value would be in between the specified 2.2V and 3.0V supply value. Of course from the tendency significantly closer to 2.2V performance than the 3.0V.

    Best regards

    Peter

  • Hello,

    Thanks for the reply.

    The voltage supply of the temperature sensor (not TI) will be driven by the digital output pin of MSP430.
    I(OHmax) is assumed average 100uA but 4mA during 100usec at peak according to the specification of the temperature sensor.

    Customer wants to know that;
    In case of the use of two output pins of MSP430 to connect to the voltage supply of the temperature sensor,
    is there any known problem on the usage?

    Regards,

  • Hello,

    many thanks for the additional information. So if I understand it correctly the maximum current of 4mA would be split into two GPIOs, driving the temperature sensor. If this is correct, I don't see an issue from the MSP430 side, in terms of potential overloads on these GPIOs.

    Though of course it needs to be considered from the temperature sensor side, that dependent on the current flow and the profile of the loading current, the supply through a GPIO might have negative impacts on the performance of the temperature sensor. This is due to two aspects. The voltage will be dependent on the current and the RDSon of the GPIOs of the MSP430, and all noise, e.g. resulting from digital modules on the MSP430, will introduce noise into the MSP430 supply and thus also to the GPIO output voltage. It depends on the temperature sensor design, and its power supply rejection ratio, and of course also performance requirements, whether this can be tolerated or not.

    There are quite some things, one can do to mitigate the potential impacts, e.g. by switching off digital module activities, while operating the temperature sensor, or use additional external components at the GPIOs driving the temperature sensor, like an RC component.

    Just a few thoughts..

    Best regards

    Peter