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BQ500410A: LEDs for BQ500410A do not work as intended

Carsten Lechens
Prodigy 50 points
Part Number: BQ500410A

Hello TI,

we developed a QI-transmitter based on the BQ500410A with the MSP430. We set the LEDs to option 1 (Generic) with a 42.2 k 1% resistor. Additionally we added a yellow LED to the 3v3 as a standby. Most of the time we see the described reaction of the LEDs (charging is green slow blinking, charge complete is green on and fault is red on and PMOD or FOD is red fast blinking).

But this behaviour does not stay active all the time. Sometimes the green LED shortly blinks which i assume is a new communication start to check if still full, This would be acceptable but in some cases after this short blink the green LED does not return to the on state and stays off. The battery was not moved and the QI-transmitter is all the time powered which can be seen by the yellow standby LED we added.

Any suggestions on how to fix this issue? 

Kind regards,

Carsten Lechens

  • 0
    TI__Mastermind 19195 points

    Hi Carsten,

    What is LED 2 status when this occurs?

    Can you send a schematic of the circuit.

    Thanks,

  • 0 in reply to Nick Brylski
    Prodigy 50 points

    The part for the LEDs is the same as in the typical application of the datasheet. The marked up components are not placed.

    The red LED is off, 3v3 yellow LED is on and green LED is off while a "full" battery which was charged by the system is on top of the coil. The battery is fixed in position and not moved.

  • 0 in reply to Carsten Lechens
    TI__Mastermind 19195 points

    Hi Carsten,

    Both LEDs off indicates standby mode, you can change LED control option to 2 to have green LED stay on.

    Best,

  • 0 in reply to Nick Brylski
    Prodigy 50 points

    Hi Nick,

    in LED control option 1 a fully charged battery should be shown by LED green on. Why does the LED turn off? The battery laying on the system is fully charged and as stated in my first text the green LED turns off for a moment (10-15 minutes i would guess) and then the LED turns on for a while and off again and so on. I want the option 1 as it is stated in the datasheet but it does not work as described in the datasheet.

    Kind regards,

    Carsten

  • 0 in reply to Carsten Lechens
    TI__Mastermind 19195 points

    Hi Carsten,

    The problem could be the Charge Complete signal for the RX. 

    TX (BQ500410A) is expecting a charge complete signal (EPT01) to power down and set the solid green LED.

    But it will need to power up every 5 sec or so to check if the RX is still there and needs more power.  When the RX is powered up it needs to respond with EPT01 to keep TX in a charge complete conditions.

    Now if the RX is acting up and not sending this sometimes or the communications has problems it could cause the unit to leave charge complete and enter start up state.  In this condition the LEDs may change states.

     Test would be to check what the RX RECT pin is doing.  At charge complete it should only reply with a single packet when the TX pings unit.  Longer reply indicate the above issue.

    Best,