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TPS57112-Q1 question

Other Parts Discussed in Thread: TPS57112-Q1

I have question of TPS57112-Q1.

Please see an attached file.

TPS57112-Q1 Question.pptx
  • Sato-san,

     

    Q1) The values in the electrical characteristics table are measured on our devices, and it is determined across all devices and temperatures. Yes, the calculator will be more accurate at room temperatue, so I would use that to determine the appropriate RT value, but keep in mind that the switching frequency can shift similar to the min and max values in that table.

    Q2) Please look at the datasheet figure 2 and figure 5 for an estimate (at a different frequency), but I would say that 10% sounds reasonable.

    Q3) Refer to the Synchronize Using the RT/CLK PIN on PG17. The rising edge of the PH is synchronized to the falling edge of RT/CLK pin, so you should see similar accuracy between your clock and the switching of this device.

    Q4) You can use 2.35V as the minimum value for VIN UVLO STOP.

  • Hello Alexander,

    Thank you for reply. I have question of frequency precision.

    Q1) Switching frequency is 447.1kHz when Rt=400kohm.

    What percentage does the precision become at the time of 447kHz switching frequency?

    Frequency precision is "-11.8%? and + 34.2%?" (Because Min:400k,  Max:600k )

    Q3)Is it precision same at the time of external synchronization?

     

  • Q1) I guess you can say that but it isn't a very good estimate. I would say that the precision for a single device is closer to +/-10% and that each device has a slightly different switching frequency at Rt=400kOhm

    Q3) The moment you add an external clock, the precision gets worse because it is adjusting to this clock. Once it is adjusted then it should be switching in line with the clock edge. So it greatly depends on that external clock.

  • Hello Alex,

    Thank you for your support.

    Q3)Should I think about only the precision of the external clock?

    Is it not necessary to think about the precision of the device?

    When it is necessary to think about the switching frequency precision of the device,

    please tell me the switching frequency precision.

     

  • Sato-san,

     

    No you have to take in account both the external clock and the TPS device. However, the external clock will make up a majority of the precision calculation, while the contribution of our device will be based where we identify the clock edge. There is not enough data for me to give you any specific numbers however.