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MSP430FR2433: As a pin attribute, what does "buffer type" tell me?

Thomas Foxcroft
Expert 2981 points
Part Number: MSP430FR2433

I know about buffers, but table 4-1, "Pin Attributes," of the data sheet is not clear about is its context and usage, other than as a pin attribute. I have some view of their possible meanings, but I want to be made clear about their meanings.

  • What is meant by the LVCMOS (low voltage complementary metal oxide semiconductor) type of buffer and how is it used at the pin?
  • What is meant by an Analog type of buffer and how is it used at the pin?
  • What is meant by a Power type of buffer and how is it used at the pin?

Furthermore, in table4-3, "Buffer Types,"

  • What is meant by "PU or PD?"
  • For LVCMOS buffer, the strength of this buffer is referred to section 5.11.4, "Digital I/Os." Where in that section is buffer strength mentioned?

  • 0
    Guru 18855 points

    Power is a type of input (Vcc, Vss, etc.) and not a buffer type. PU and PD is shorthand for pull-up and pull-down.

    Digital inputs have a buffer, frequently of the Schmitt type between the pin and internal functions. Analog inputs aren't buffered because that would just cause trouble. Unless you added some sort of unity gain analog buffer to each pin. Yuck. The pin diagrams (6.11) show this in detail. It shows a transmission gate between the pin and the analog section. I suppose you could call that a buffer but I wouldn't.

    5.11.4 tells you the output voltage for a particular output current. That is its "strength".

  • 0
    TI__Guru 56685 points

    Hello,

    LVCMOS type is used for most pins and describes the characteristics for "digital" functionality aka the SCHMITT-TRIGGER I/O. 

    Analog is for analog functionality, to reduce leakage current typically, such as ADC input, DAC output, etc.

    Power is for power and reference pins. 

    The requirements for these use cases are different and thus need different I/O structures and or paths to meet those requirements. All this information is trying to tell you is the pin behavior is different depending on the use case. You can look at the pinout diagrams for more description of pin structure/muxing.

    PU - Pull Up

    PD - Pull Down

    Strength is described in parameter Rpull. 

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