• State TI Thinks Resolved
  • Locked Locked
  • Replies 9 replies
  • Answers 2 answers
  • Subscribers 62 subscribers
  • Views 567 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

Original question:

TPS61201: Unexpectedly high (3x) input current at 1.5v in Power Save mode

TPS61201: Unexpectedly high (3x) input current at 1.5v in Power Save mode

douglas malnati
Prodigy 130 points
Part Number: TPS61201

Hi,

As referenced in the other thread, I did use the LPS3015-222MRB power inductor and the issue was lessened, but not resolved.

Ultimately I am finding the TPS61201 isn't able to deliver more than 100-200mA or so before the output voltage collapsing or the input current getting very high.

My output power requirements are 3.3v with upwards of 200-250mA for up to 2 min sustained.

My input power requirements are at most 3v batteries, but ideally 1.5v or less.

As I've said if I use a 1.5v battery, the input current is extreme (800mA+) for minor loads.

I believe I've wired the regulator correctly.  I've also used the regulator in a breakout board and produced the same results.

Can you give some feedback on what I might be doing incorrectly if I'm experiencing these results?

Or tell me if I'm attempting to use the device incorrectly in my expectations?

Thank you.

doug

  • 0
    TI__Mastermind 46905 points
    could you check if the IC is damaged? you can measure the impedance between the SW and GND pin?
  • 0 in reply to Jasper Li
    Prodigy 130 points
    Hi Jasper,

    I have used multiple ICs, all seem to exhibit this behavior.

    > measure the impedance between the SW and GND pin

    SW means the L (inductor) pin?
    Are you asking about AC impedance? Or DC resistance? I don't have a way to test AC impedance.
    And do you mean the bare module L pin to PGND? Or a module with the inductor and caps, etc?

    Thanks.


    doug
  • 0 in reply to douglas malnati
    TI__Mastermind 46905 points
    hi
    1. could you measure the Vbat, L and VOUT PIN waveform when you observed issue?
    2. you can use multimeter to measure the DC resistance between L pin and GND pin to check if the IC is damaged
    the blog may help us to quickly debug the issue
    e2e.ti.com/.../tips-in-debugging-a-boost-converter
  • 0 in reply to Jasper Li
    Prodigy 130 points

    Hi Jasper, thank you, I am following up on this shortly but have been delayed.  Hope to reply with results soon.

    Thanks.

    doug

  • 0 in reply to douglas malnati
    Prodigy 130 points

    Hi Jasper,

    I have taken both the measurements you asked for.

    > 1. could you measure the Vbat, L and VOUT PIN waveform when you observed issue?

    Yes, here is a scope capture where Vbat="REG In", L="L", and VOUT="REG Out".

    I have three screenshots:

    • Constant draw of 50mA
    • Constant draw of 200mA
    • Constant draw of 500mA

    In all cases:

    • The power supply providing power to the regulator is set to 3.0v
    • Regulator PS=HIGH (disabled)
    • UVLO tied to VIN
    • VAUX 10uF cap to GND
    • VOUT 10uF cap to GND

    Here is constant 50mA draw:

    Here is constant 200mA draw:

    Here is constant 500mA draw:

    > 2. you can use multimeter to measure the DC resistance between L pin and GND pin to check if the IC is damaged

    I did do this.  The device was disconnected from all power, all pins disconnected, no caps nor inductors present.

    The reading is approx 5 mega-ohm between L and GND (same as L and PGND).  Leaving the probes in slowly causes the resistance to decrease over time.

    > the blog

    I will read through the blog and look for issues I may have.

    Thank you again for the help.

    doug

  • 0 in reply to douglas malnati
    TI__Mastermind 46905 points
    is there long cable between the power supply and the IC? why does VBAT voltage oscillate? you may need to add input capacitor to stabilize the input voltage.
  • 0 in reply to Jasper Li
    Prodigy 130 points

    Hi,

    I swapped the input power source for a pair of AA batteries and similar ripple.  I added a large (47uF) cap and that did smooth the input more.

    However, the fluctuations on the L and VOUT pins remained chaotic.

    What else can I do to diagnose this?

    At the moment I am testing on a breakout PCB for the regulator, as opposed to the genuine product I built using the regulator before.

    For my breakout, I am using the correct inductor (2.2uF power inductor 1.2+Amps), but my output caps (10uF) are electrolytic instead of ceramic.  However, the waveforms I'm seeing in my test setup match what I saw on my PCB when using output caps of ceramic (10uF).

    Layout of the components near the regulator was stated to be important, which I have limited control over in my test setup.  Also, since I see similar waveforms on my PCB, I don't assume layout is to blame because it's so different.

    Can you think of most-likely issues which can affect this?

    Do you agree that the performance I'm getting from the regulator is not what I should expect and that there is some issue?

    Thank you.

    doug

  • 0 in reply to douglas malnati
    TI__Mastermind 46905 points
    yes. this is not expected behavior. there should be some issues. could you share your old PCB and current PCB?
    i would also suggest you apply an EVM for reference.
    please note that do not use electrolytic capacitor instead of ceramic cap.
  • 0 in reply to Jasper Li
    Prodigy 130 points

    Hi Jasper,

    I purchased a TI evaluation module from DigiKey.

    https://www.digikey.com/product-detail/en/texas-instruments/TPS61201EVM-179/296-31237-ND/1908016

    I will take a few measurements and get back to you.

    Thanks.

    doug