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DAC80502: RSTSEL pin function and SPI level check

Yuxi Liu(Tony)
Expert 3220 points
Part Number: DAC80502
Other Parts Discussed in Thread: DAC60508, DAC80508, DAC81402, DAC61402

Tool/software:

Hi TIer

My customer want us this chip for medical high voltage control.

For RSTSEL pin , we see the describe in datasheet.

How do I change the RSTSEL voltage while the DAC is outputting voltage(working), will I make the DAC output to 0V? 

Also, what are the restrictions on the use of the RSTSEL pin function? When VDD is greater than 5V, how is it controlled? 

Finally, if VDD=5.5V, can the SPI communicate using 5.5V logic or 3.3V logic? 

Do we have a higher price/performance chip, more performance than the DAC80502, we have an ADI competitor ad5689, they have good performance, But a little more expensive .

Thank you very much.

  • +1
    TI__Mastermind 42203 points

    Hi Tony, 

    No, changing RSTSEL will not affect the DAC output during operation. Issuing a SOFT-RESET will 

    VIH is 1.62V no matter what VDD is. So, RESET select operates just fine with a 5V VDD. SPI can communicate with 3.3V or 5.5V logic. The only restriction is that the inputs must be less than VDD (you can't use VDD=3.3V and 5.5V logic level). 

    What specs in the AD5689 do they care about that DAC80502 doesn't meet? They are very comparable based on what I see in the spec table. We have better INL, and we include a precision internal reference which the AD5689 does not. 

    Best,

    Katlynne Jones 

  • 0 in reply to Katlynne Jones
    TI__Expert 3220 points

    Thank you very much.

  • 0 in reply to Yuxi Liu(Tony)
    TI__Expert 3220 points

    Hi Katlynne

    After discuss with customer , customer need a DAC which have hardware pin which can let DAC output 0V.

    Could you help me find a DAC which same performance than DAC80502?

    Thank you very much.

    Some spec need:

    1、Need internal reference.

    2、able to output achieve 2 times of internal reference.

    3、zero-code error≤1.5mV

    4、need hardware control output return to 0V.

    5、≥12bit 

    6、Output range ≥5V  （0~+5V）

    7、Reliable and stable

    8、TSSOP is nice

    9、The voltage is configured for the transition time to the output＜20uS

  • 0 in reply to Yuxi Liu(Tony)
    TI__Mastermind 42203 points

    Hi Tony, 

    The DAC80508 in the same family has a clear pin to set the outputs to 0V. I think this would be the best alternative. If the customer only needs 12-bit they can use the DAC60508.

    If they customer still prefers a 2-channel device, they can consider the DAC81402 (or DAC61402). 

    Best,

    Katlynne Jones

  • 0 in reply to Katlynne Jones
    TI__Expert 3220 points

    Hi Katlynne

    Thank you for your reply.

    I discuss with customer , they don't use 8 ch DAC.

    In terms of  DAC81402 (or DAC61402)  ,  offset spec not good.

    Do we have more suggestion chip? 

  • 0 in reply to Yuxi Liu(Tony)
    TI__Expert 5090 points

    Hi Tony,

    Let's meet for a short call and understand the customer needs better. After that I can suggest best possible DAC part which can serve the customer's needs.

    Please check your mail.

    Thanks,
    Sanjay