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TPS40210: Vfb actual variation value

Nariaki Ogasawara
Intellectual 1215 points
Part Number: TPS40210

Hi,

 The specification of Vfb is 686mV to 714mV (700mV +/-2%) at all condition. Figure 5.Reference Voltage Change vs Junction Temperature in Typical Characteristics is -0.6% to 0.4%. I think +/-2% is Vfb at 25deg C (+/-1%) with this. 

 The customer wants to know the actual variation value for his application.

The question is

1. Is it possible to show the actual variation value? (Because we don't know the variation of Vfb@25deg C.)

2. If temperature range is 0 to 50 deg C, what is the min/max value of Vfb?

Regards,

Ogasawara

.

 

  • 0
    TI__Intellectual 2655 points
    Hi Ogasawara,
    Different device has the variation.
    EC table spec 686mV to 714mV (700mV +/-2%) : we can guarantee all the devices, temperature range is -40 to 125 deg C.
    Typical Characteristics is -0.6% to 0.4%: We test a typical device to show Vfb vs. Temp.
    1. Is it possible to show the actual variation value? (Because we don't know the variation of Vfb@25deg C.)
    From EC table, 693mV to 707mV @ 25degC
    2. If temperature range is 0 to 50 deg C, what is the min/max value of Vfb?
    For a typical device, you can find this from Figure 5.
  • 0 in reply to Jing Ji
    TI__Intellectual 1215 points

    Hi Jing,

     Thank you for your response.

     I would like to confirm about Question 2. Is there any worst case data of temperature?   

    Regards,

    Ogasawara

     

  • 0 in reply to Nariaki Ogasawara
    TI__Intellectual 2655 points
    Hi Ogasawara,
    Normally, we have the data @-40 to 120 degC and analysis them @-40 to 120 degC. But we don’t analysis them @0 to 50 degC. If you want it, I need to check the database and analysis it, it will need some times.
    I suggest you could estimate min/max value of Vfb @ 0 to 50 deg C based on min/max value of Vfb @ -40 to 125 deg C and the Temp trend (Figure 5).
  • 0 in reply to Jing Ji
    TI__Intellectual 1215 points
    Hi Jing,

    I'll try to estimate min/max value of Vfb @ 0 to 50 deg C.

    In the case of Vvdd is 4.5V,
    The min voltage Vfb@25 deg C is 693mV and -0.5%@-40 deg C, the calculate of min voltage is 989.5mV. The other hand the min voltage at -40 to 125degC is 686mV.
    The difference of the calculation and datasheet is 3.5mV or 0.05%, this is the correction value for min value. Which is better to use 3.5mV or 0.05% for estimation of min value at 0 to 50 deg C?

    I have one more question for estimate the other Vvdd.
    The figure 5 has Vvdd=12V, 4.5V and 52V, the voltage change of 12V is the smallest at 25 to 125 deg C. What is the Vvdd with the smallest change at 25 to 125 Deg C? Is it 12V?

    Best Regards,
    Nariaki Ogasawara
  • 0 in reply to Nariaki Ogasawara
    TI__Intellectual 2655 points
    Hi Ogasawara,
    I try to find TPS40210 database, but I found this device is transferred from another product line, I can't find the original data.
    FB voltage is based on design, I am not sure "the smallest change at 25 to 125 Deg C? Is it 12V?"
    You could estimate it from datasheet. But I can't tell you the accuracy data. I am so sorry.
    Another thing, if your application is care about Vout accuracy, I suggest you could add a LDO at the output of TPS40210.
  • 0 in reply to Jing Ji
    TI__Intellectual 1215 points

    Hi Jing,

    The customer application is 19V, he also wants Vfb vs temperature characteristics for 19V. Can you ask this to another product line?

    Best Regards,
    Nariaki Ogasawara

  • 0 in reply to Nariaki Ogasawara
    TI__Intellectual 2655 points
    Hi Ogasawara,
    I will try to contact another product line, but it will need some time.
    I suggest you could ask customer to use the value as you estimate.