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BQ51050B: TS/CTRL error causing power transfer stops from BQ50002EVM-607 to custom made BQ51050B based receiver

Muhammad Akram Karimi
Prodigy 245 points
Part Number: BQ51050B
Other Parts Discussed in Thread: BQ500511A, TPS63051

Hello everyone,

I had posted it earlier as well but could not get satisfactory explanation about my error.

I am testing my custom made BQ51050B based receiver which is being powered up using  BQ50002EVM-607 Tx. Here is my initial schematic:


I am using 732-6211-ND (7.5uH) Rx coil (although the caps in the schematic are for 8uH coil:: Does that make much of a difference?)

The problem is that; when I start the BQ50002EVM-607 Tx (with Rx coil placed on top); I hear buzzer sound and Green LED blinks (at about 1.25Hz) indicating that the power is being transferred. Charging LED on Rx board also lights up. This happens for few seconds after which the Green LED(D6) stops and D5(RED LED) lights up and the charging LED on Rx also stops. It means some error occurred (I am unable to figure out what is the error).

Here are the scope captures(Vrect in Yellow and V_TS in GREEN) I got:

D5 (RED) LED lights up at the time when the voltages drops. If we see the datasheet it seems like a TS_GND fault.

Bill (Application engineer at TI) had suggested to increase the R_FOD from 140 ohm and shorting R23 on Tx EVM to disable FOD functionality.

I shorted R23 on Tx EVM and increased R_FOD from 140 till 1000 ohm on custom Rx board but the problem remains the same.

I have tested with drained and semi-drained 3.7V Li-Ion batteries. Same error

I tried with applying 40mA load across the battery terminals-Same error

After few attempts; now even the charging LED on custom Rx board has stopped to lit up which used to light up for at least few seconds before.

Please help me in this regard. I really need to get it working asap.

Thanks

  • 0
    TI__Guru 65806 points
    Muhammah
    Take a look at bq500511A data sheet Table 2, it will list the faults and time between retry. The time between retry will give an indication of which fault is commanding the TX to shutdown. EPT-0X value can be compared with bq51050B Table 1 to identify area to look at. A TS over temp (or under) will shutdown the TX for 5 min (time is determined by TX). The over temp End Power Transfer is 03 (EPT03), TX data sheet table 2. If we look at RX table 1, EPT03 is value 0x03 and condition is identified to the right.

    The mods you made to TX R23 will rule out FOD as the cause of the fault condition.

    In the above scope capture the V-Rect does not look correct. We see the voltage increasing under command of the control error packets then it drops. This could have to do with the output voltage turning on. Out should be off until V-Rect reaches about 7V, but should not go through this cycling.
    What does Out and V-Rect look like?

    Also:
    1.) Test only with a battery or battery emulator on the output.
    2.) Disconnect the TPS63051 until the battery charger is working
    3.) How may PCB are showing this problem?
  • 0 in reply to Bill Johns
    Prodigy 245 points

    Dear Bill,
    Thanks again for your kind reply.
    Here are the answers for your last 3 questions:
    1. I have tried it only with the battery as mentioned in the post as well
    2. This was my first step of debugging; I have disconnected TPS63051
    3. I have made only 1 PCB; and soon will make more to test. Do you suspect any problem in IC or what?

    This is the top layer which contains the BQ51050Q IC and its components.P1 is where I put coil and P3 is where I put the battery.

    What do you mean by OUT voltage? Do you mean BAT voltage?

    One more thing is that all of my caps connected with coil are note rated as 50V; some of them are 16V as well (I think it's fine because in TIDA-00329 design; TI is also using 16V caps with same IC).

    Can the wrong values of caps connected with coil (Because Ls and Ls' are not exact for which I calculated the values of caps), be a problem?

    I will also test the Rx with another commercial Qi complaint receiver.

    Attached is the zip file containing all the altium files of the project including schematic, top, bottom layer etc.

    Thanks4186.WPT_Compact_v3_March29.zip

  • 0 in reply to Muhammad Akram Karimi
    TI__Guru 65806 points
    What do you mean by OUT voltage? Do you mean BAT voltage? ----On the scope capture yes it is BAT (bq51050) on other devices it is OUT.

    Do you suspect any problem in IC or what?---I have seen assembly issues with PCB such as bad solder joints and missing parts.

    Can the wrong values of caps connected with coil (Because Ls and Ls' are not exact for which I calculated the values of caps), be a problem?---What I am seeing is a big problem not a little one. The tuning can be off a small amount and the device will start.

    Thanks for the files looking at them now.
  • 0 in reply to Bill Johns
    Prodigy 245 points
    Dear Bill,
    I have some questions with regard to interpreting the LED duration to know about the error reason:
    Please answer these questions with reference to the scope capture I sent you in original post:
    1. What do you call a retry? In scope capture 1 big box is 1second and
    a) I can see that the voltage drops from 5.5V to 3.3V after around 0.5 second interval and then rises again to 5.5V.
    b) We can also see that there is a big drop from around 5V to 0V and then rise again.

    What should I interpret as retry interval?

    2. What is meant by "Immediate" duration in table 2?

    3. Some retry duration are overlapping in table 2. e.g. EPT-02 and EPT-06 (both infinite). how to distinguish between these faults?

    Looking forward to your help.
    Thanks
  • 0 in reply to Muhammad Akram Karimi
    TI__Guru 65806 points
    What is meant by "Immediate" duration in table 2?----The TX will shutdown and restart in about 40mS, so Immediate will be about 40mS.
    Some retry duration are overlapping in table 2. e.g. EPT-02 and EPT-06 (both infinite). how to distinguish between these faults?---An infinite will not restart, the TX will turn off and not restart until input power is reset.