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What is MAX14661 switching time after CS raised?

Category: Datasheet/Specs
Product Number: MAX14661

When using the MAX14661 in SPI mode, the datasheet says under "SPI Interface" that the switches are updated at the rising edge of CS after writing 32 bits to the 4 direct registers. But it is not clear how long it takes for the update occur.

Figure 2 shows it to be the sum of tOFF and tBBM and lists tOFF typical of 5us and tBBM min of 0. But it does not say what the maximum of either one is. 

Figure 2 also shows the update time as equal to tON which has typical 13us and max 25us.

It is not clear if the maximum update time is 5us or 25us.

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  • Hi  ,

    The update time after the rising edge of CS is primarily determined by tON, which means the maximum update time is 25µs. The sum of tOFF and tBBM is relevant for understanding the switching characteristics but does not determine the maximum update time directly.

    So, the maximum update time you should consider is 25µs.

    Best regards,
    Christian

  • Hello ,

    Thanks for the info. That does seem like a very long time though. I assume the typical is 13us. It only takes 3.5 us to send 32 bits of data via SPI, but then 25us to switch?

    The wording is a bit odd. For the tON is says:

    ... close AB_ and COMA or AB_ and COMB together

    It seems to be referring to a very particular situation. It's not clear what this means.

    While for the tOFF it says:

    .. open COM_ and AB_ together

    In our case, we would never have COMA and COMB connected to a given ABXX.

    We have some of the chips and will try and measure it.

Reply
  • Hello ,

    Thanks for the info. That does seem like a very long time though. I assume the typical is 13us. It only takes 3.5 us to send 32 bits of data via SPI, but then 25us to switch?

    The wording is a bit odd. For the tON is says:

    ... close AB_ and COMA or AB_ and COMB together

    It seems to be referring to a very particular situation. It's not clear what this means.

    While for the tOFF it says:

    .. open COM_ and AB_ together

    In our case, we would never have COMA and COMB connected to a given ABXX.

    We have some of the chips and will try and measure it.

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