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Setup and hold time of PGA870

Hello, I'm FAE of distributor in Japan.

My customers ask me spec,but not in data sheet.

Now they already built system with No latch mode.

They think to modify mode and ask some questions.

Q1) In case no latch Mode, What value  ns does it need to fix internal Gain after changing worst gain bit pin?

Q2) I think gain settling time means reliable output after fixing internal gains,is it correct?

Q3)In case edge triggered mode,What value ns maximum tSU and tHOLD and tLATENCY?

Regards

Shinya Muramatsu

  • Muramatsu-san,

    To answer your questions:

    Q1) In case no latch Mode, What value  ns does it need to fix internal Gain after changing worst gain bit pin?

    Ans: The spec for digital pins to propagate internally to fix internal gain or tLATENCY is typically 6.4ns. Once the digital codes are set, it takes a minimum time of 5ns for the gain at the output to settle to the correct gain settings. So, I would think the typical time required for the gain to transition in no latch mode from the time when the digital pins are at the correct logic level to the output settling at the correct gain settings is 11.4ns. This condition is assuming that all the digital pins in no latch mode are at the correct logic levels for a particular gain setting.

    Q2) I think gain settling time means reliable output after fixing internal gains,is it correct?

    Ans: Yes, the gain settling time means reliable output after fixing the internal gains.

    Q3)In case edge triggered mode,What value ns maximum tSU and tHOLD and tLATENCY?

    Ans: For the edge triggered mode, the setup time, hold time and tLATENCY are as given in the Digital Inputs table in the datasheet.

      

    Best Regards,

    Rohit

  • Rohit-san

    Very thanks for your reply.

    And sorry to late reply because I had a vacation and business trip.

    Sorry,I didn't inform you enough information.

    Our customer ask us worst setup time and hold time.

    We checked typical data is in datasheed,but There are no maximum time data.

    I changed their questions.

    If TI can't garant it ,please inform simulation value or reference value.

    Q1) In case no latch Mode, What maximum time value  ns does it need to fix internal Gain after changing worst gain bit pin? I found worst settling time is 20nS in E2E. I need maximum propagate internally information.

    Q2)closed

    Q3)In case edge triggered mode,What value ns are they maximum time of tSU/tHOLD/tLATENCY?

    Regards,

    Shinya Muramatsu.

  • Muramatsu-san,

    TI cannot guarantee this number, but simulation value or reference value could be:

    Q1. The simulated maximum time for digital signals to propagate internally could be from 10ns to 12ns in No latch mode.

    Q3. In edge triggered mode, the tSU can be as long as possible with typical being 2.5ns, tHOLD is 0 and tLATENCY is the same as 10ns to 12ns.

    Best Regards,

    Rohit