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TPS61202EVM-179: Current capability and solar input

John Heaton
Intellectual 550 points
Part Number: TPS61202EVM-179

I am testing the TPS61202EVM and ran into an issue. Using a programmable DC supply set at 5.0v connected to input. Adjustable resistive load + DVM to monitor voltage. When I start at 0 load, output is 5.0v as expected. As I increase the resistive load pot, as I approach 500ma the output suddenly loses output voltage control. I am using the standard EVM and thought the chip was suppose to output 600ma? Why is ouput current causing this issue when the supply is 5v?

  • 0
    TI__Mastermind 46905 points
    could you measure the operating waveform of input, SW pin, and output when the output current is closed to 500mA but VOUT not out of control?
    what is your input voltage range? why need a boost converter if the input is 5V.
  • 0 in reply to Jasper Li
    Intellectual 550 points

    I could not identify a SW pin on this device?

    My input voltage range for my real use is 1<>5v for a small solar panel, that's why I am considering its use.

    The reason I started trying to verify the output was I was seeing the output voltage drop inexplicably. So decided to verify the output using standard voltage supplies and loads. 

    1. After hooking up the test setup again to get you this data I noticed that the current at 5v is now closer to the spec. See image 1. I believe my clips on the output were maybe causing the issue? 

    2. I lowered the input voltage to see if the device would maintain the current and the original issue came up. As you can see from image 2, the output is 5v, 3v input @ 450ma. I can't go above that without losing control.

    3. As I increased the resistive load to just above 450ma, it loses control. See image 3

  • 0 in reply to John Heaton
    TI__Mastermind 46905 points
    CH1 is input voltage and CH2 is output voltage? why the CH1 is zero voltage in Figure3.
  • 0 in reply to Jasper Li
    Intellectual 550 points

    Actually now that I look at that picture, I notice that the current limit has been reached on the programmable power supply, which drops the voltage. So I just adjusted it up, and the device worked just fine. So thanks for your help and I consider the issue closed.