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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 (part 3)

douglas malnati
Prodigy 130 points
Part Number: TPS61201

Hi,

There are 2 other threads where I've been trying to investigate the TPS61201.

First: https://e2e.ti.com/support/power-management/f/196/t/672777

Second: https://e2e.ti.com/support/power-management/f/196/t/691734

In those threads I have extensively documented how the TPS61201 seems to fall well outside expected behavior when using a 1.5v power source.

The last suggestion given to me was to try purchasing a demo board (link), which I did, and I am now reporting that it also appears to behave just as poorly.

Can you please give me some insight into what is going wrong?

Specifically, that demo board, powered at 1.5v from a lab bench power supply will draw 367mA when attempting to produce 50mA output at 3.3v when PS=HIGH (power save disabled).

Thanks for the help.

doug

  • 0
    TI__Mastermind 21565 points
    Hi Douglas:
    That's a long story. So let's focus on the EVM first. According your waveform, it seem the Vout drops a lot. I wonder what happened in that moment? Do you short the PS to GND or VIN?
  • 0 in reply to Minqiu Xie
    Prodigy 130 points

    Hi Minquiu,

    The first drop is when I activated an electronic load system designed to draw a constant current.

    I have reproduced below a simpler test using a 1.5V battery as input and a 22ohm resistor as the load.  This is different loading than my first example.

    The drop you see in output voltage corresponds to me making a complete circuit to the regulator positive and negative terminals with the 22ohm resistor.

    Below I have the capture at 12.5 MS/s both zoomed out and zoomed in.  BAT is the battery voltage, VOUT is the regulator output voltage.

    Can you give me some ideas about what to look at next?  This is about as simple of a setup as I can think to make.

    Thanks.

    doug

  • 0 in reply to douglas malnati
    TI__Mastermind 21565 points
    Hi Doug,
    We could see that the Vbat is drop a lot with the load. What's the current now? Is it normal for the battery?
    Please use a power supply to replace the battery, and make the line short to reduce the resistance. And do the test again.

    Besides, do you have current probe? The diagram with current of inductance is better, like below: e2e.ti.com/.../tips-in-debugging-a-boost-converter
  • 0 in reply to Minqiu Xie
    TI__Mastermind 21565 points
    Hi Doug:
    I haven’t heard back from you, I’m assuming you were able to resolve your issue. If not, just post a reply below (or create a new thread if the thread has locked due to time-out)
  • 0 in reply to Minqiu Xie
    Prodigy 130 points

    Hi Minqiu,

    Apologies, I have been delayed in getting you the measurements.

    The issue is not resolved.

    I will aim to get you more details in a day or two.

    Thank you again for your help.

    Doug

  • 0 in reply to douglas malnati
    TI__Mastermind 21565 points
    Hi Doug:
    You're welcome, it's my pleasure to support.
    And please notices that the Chinese new year is coming, the reply maybe delay~~
  • 0 in reply to Minqiu Xie
    Prodigy 130 points

    Hi Minqiu, happy new year!

    I am closing this ticket.

    I looked and there was a voltage drop from the bench power supply to the load due to distance and wire gauge.  This explains some of my questions/observations.

    I resolved this by using 12 gauge wire, banana jacks, and a shorter distance to the load.

    Further analysis of the regulator showed other questions about performance at a given voltage.  However, this is not my primary focus for the moment, so I have no questions for you.

    My focus now is the inrush current associated with powering up subsystems on the board with a load switch, which was what ultimately was causing the regulator to draw so much current (making up for the voltage drop from the PSU).  I'm finding some success using a PWM approach to slow-starting the subsystem despite it not being designed for that.

    Thank you for the help.

    doug