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BQ24650EVM-639: Test Procedure 2.7.3 not outputting 0.2A

Beau Rogers
Prodigy 240 points
Part Number: BQ24650EVM-639

I am trying to test the bq24650EVM development board as per the user manual but am seeing two issues:

- when I test J2(V(OUT)) on step 2.7.1 the voltage is 12.6V.
- When I do step 2.7.3 (load #2 at 8V) I do not see 0.2A going through the load. 

I have a bit of confusion load #2 as I do not have a An HP 6060B or equivalent, so I am using a power supply that has reverse polarity protection. When I did not get the results I was after, I tried using a resistor that would deliver 12.6V at 0.2A of current but did not happen. Additionally, LED STAT1 illuminates regardless of load connection. Can someone let me know what kind of load I can use instead and/or where the problem may be?

Thank you in advance.

  • 0
    TI__Mastermind 24075 points
    Hello Beau,
    1. The user guide has an error in saying that VOUT = 0V at section 2.7.1. You are correct in measuring 12.6V at this step with a multimeter. This part has a battery absent detection scheme to detect insertion or removal of battery packs. This effect can be seen clearer using an oscilloscope and is explained in detail in section 8.3.21 of the datasheet. Thank you for bringing the mistake in the user guide to our attention.
    2. A standard power supply cannot sink current and cannot be used to mimic the load in this case. An electronic load is ideal, however for lower current measurements it is possible to use a Sourcemeter or a Kepco bipolar operational power supply/amplifier. Essentially you require VOUT to be held to a constant voltage and to be able to measure the current into the instrument (CV).
    3. Can you describe the conditions in which you see STAT1 illuminate? If you were to remove all load, are you still seeing STAT1 light up?
  • 0 in reply to Kedar Manishankar
    Prodigy 240 points
    Hey Kedar,

    That's good to hear that there is no error in the reading. I thought that was a bit strange. As I do not have the equipment to simulate the battery load I ended up using a battery and am getting rational readings. Now that I am getting rational readings, I am seeing that the STAT1 LED is off when no load present and on when charging.

    Thanks,

    Beau