• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 63 subscribers
  • Views 900 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TLV2217-33 Issue

Patrick Zeng
Intellectual 1090 points
Other Parts Discussed in Thread: TLV2217

Hi Team,

  My customer met an issue with TLV2217.  As it's shown below, there's an inrush current-limit resistor in series with input of TLV2217. When the resistor Rx is below 30ohm, TLV2217 works fine. When customer increases the resistor to above 70 or 80ohm, TLV2217 stops regulating normally and outputs 2.6V only , meanwhile drawing a lot more current from the input.

  Similar results happened in LM7812, which I did a test on. I wonder if it's related to LDO's internal circuit or is it a stability issue? It'll be appriciated if you can introduce me the details. Thank you...

Regards,

Patrick

  • 0
    TI__Mastermind 24975 points
    Patrick,

    Based on using the 30 Ohm in series, if the output load is constant, then the input voltage directly to the TLV2217 should be about 11.1V, which should not cause any issues.
    Based on using the 70 Ohm in series, if the output load is constant, then the input voltage directly to the TLV2217 should be about 9.9V, which also should not cause any issues.
    I see in one of your figures that the input voltage is measure to be 2.7V, this concerns me, because it means that the output load is much more than expected – on the order of 130mA.
    With this high of a current, the input voltage drops across the 70Ohm resistor, making it so that there is not enough headroom for the output to regulate to 3.3V.

    Are we sure that the output load is only 30mA? What is causing this load? Do you have a schematic to show the load?
    In the setup with 30 Ohms, what is the input voltage directly to the TLV2217-33?
    I don’t expect there to be a stability issue, but if you take a scope shot of the input and the output, do you see any oscillations?

    Best,
    Michael