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BQ77PL900EVM-001: Basic operation test problem

Evan FERREIRA
Prodigy 50 points

Part Number: BQ77PL900EVM-001

Hello,

I encountered an issue with the evaluation module board when I'm trying to follow the instructions of the section 4.5 Basic Operation of the user guide.

I'm supplying 20V for the BATTERY side.

When I link the PACK side to the load, I cannot see any voltage, whereas in the meter tab of the power supply I can see there a voltage. 

The resistors used are 100Ohm ones, is it a problem ?

 

Thanks in advance for you answer,

Evan

  • 0
    TI__Guru* 81035 points

    Hi Evan,

    I am not sure. Are you connecting the 20V to both the BAT and PACK side together?

    May I ask why you selected the BQ77PL900? This is a very old device that is not widely used. The BQ76930 is much more popular and offers many more benefits. The BQ76942 is the newest 10S monitor and has the best performance and features.

    Regards,

    Matt

  • 0 in reply to Matt Sunna
    Prodigy 50 points

    Hello Matt,

    As written in the datasheet, the 20V are supplied on the BAT side and the load is linked to the PACK side.

    I noticed that the opposite works, if the power supply is linked to the PACK side and supply 20V, I can see the voltage (19.47V) on my load linked to the BAT side.

    For you second question, I think that it's linked to the price of the EVM (our final purpose is to create our own protection module).

    Thank you,

    Evan

  • 0 in reply to Evan FERREIRA
    TI__Guru* 81035 points

    Hi Evan,

    Are you doing Step 3 in the Basic Operation steps to wake the device? It might be good to change to 200 ohm resistors if you have them available. I do not know if 100 ohms will cause an issue.

    Regards,

    Matt

  • 0 in reply to Matt Sunna
    Prodigy 50 points

    Hello Matt,

    First I bought 180 Ohm resistors and replaced the old ones.

    I did the step 3 in the basic operation, I supplied 9V on the PACK side and the Communication starting but an Under Voltage was detected.

    There were still 20V supplied at the BAT side.

    Is there a certain amount of current that we have to provide on the  BATTERY side or on the PACK side ?

    If you have any idea please let me know.

    Thank you for your help.

    Evan

  • 0 in reply to Evan FERREIRA
    TI__Guru* 81035 points

    Hi Evan,

    I'm not sure since I've never used this EVM. As I mentioned, this is a very old device. I highly recommend using one of the newer battery monitors like the BQ76930 or BQ76942. 

    Best regards,

    Matt