• State Resolved
  • Locked Locked
  • Replies 20 replies
  • Subscribers 64 subscribers
  • Views 3415 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ51013B

Kavindu Dharmasiri
Prodigy 150 points
Other Parts Discussed in Thread: BQ51013B, BQ24040

Hello,

I'm hoping to use BQ51013B for my university project with regard to wireless power transmission.I have already designed the circuit according to the data provided in data sheet.I don't have a expert knowledge on electronics so i need a little help with verifying the circuit design. The design is attached with this question.

Thank you

  • 0
    TI__Genius 14890 points
    Kavindu,

    Make sure the capacitors that touch the AC1 or AC2 pins have a minimum voltage rating of 25V.
    The capacitors on RECT should be 16V minimum. It is difficult to see the values of those capacitors. Use the EVM as a guide for values.
    OUT should be 10V minimum.
    If you are not using CHG for an indication (LED or GPIO to a CPU) it can be left floating.
    Check out the Foreign Object Discussion in the datasheet for more details on R5 and R6. If you are building a single unit, start with leaving R5 open. If FOD calibration is needed, then R5 is generally better than R7.

    Regards,
    Dick
  • 0 in reply to Dick Stacey
    Prodigy 150 points

    Dear Dick,

    Thank you for the useful information and sorry for the late reply.I have done some certain changes of the circuit according to your guide lines.Resonance capacitors are yet to be calculated.The new revised schematic is attached.

    0743.WPT-Rx_2.pdf

    I have,

    Connected a LED to the CHG pin through a resistor

    Made Ros(R5) to 20k

    Made R6 to 66

    Made R7 to 196

    Disabled TS-CTRL

    Left AD-EN float

    Also should i have to keep R6 and R7 exactly at 66 and 196 ohms.How the removal of R5 affect the function of the circuit.What is difference between direct grounding and grounding though a large resistor.

    Thank you

  • 0 in reply to Kavindu Dharmasiri
    TI__Genius 14890 points

    Kavindu,

    R6 + R7 set the maximum current.  314/(66+196) = 1.2A.  That indicates the normal current would be no more than 1A.  The extra 20% allows for unexpected surges to keep the system still operational.  To change the current R6 is the best choice.  R7 is used for the Foreign object detection (FOD) calibration, along with R5.  

    Go to ti.com/wirelesspower for an introduction to FOD.  It's also a good spot to learn more about wireless power.

    As an overview, R7 and R5 are used in an algorithm by the receiver to calibrate for "friendly metals" in the system (something metallic in the RX system that's needed - screws, cameras, etc).  It's not a linear approximation, but R5 sets the slope of the compensation curve and R7 sets the offset.  If you need more information on that, look at the Tools & software tab on the bq51013B web folder.  The FOD calibration tool has a very nice user guide with all the details needed.

    Can you be more specific on your question about direct grounding versus through a large resistor?  Which pin?

    Regards,

    Dick

  • 0 in reply to Dick Stacey
    Prodigy 150 points
    Dick,

    I was talking about the TS-CTRL pin it is grounded using a large resister

    Thank you
  • 0 in reply to Kavindu Dharmasiri
    TI__Genius 14890 points
    Kavindu,

    The TS-CTRL pin has dual functions. The key one for the resistance is the Temperature Sense. The TS function expects a Negative Temerpature Coefficient thermistor to ground. The nominal 25C value of that should be 10k. Using a 10k resistor to ground effectively tells the device that the temperature is 25C and all is good. That is how the TS is disabled.

    The CTRL function would be to pull the pin high or low (overpowering the thermistor) and take appropriate actions.

    Regards,

    Dick
  • 0 in reply to Dick Stacey
    Prodigy 150 points

    Dear Dick.

    I did the hardware implementation for the above design. But the result is negative my transmitter is recognising the receiver circuit. I checked the transmitter with Qi enabled mobile phone and it works well (I'm using a Samsung EP-PA510 charger).The schematic and PCB layout are attached with this question. Please provide me a suitable trouble shooting procedure.

    Thank you.

    Regards

    Kavindu

    1715.WPT-Rx.pdf

  • 0 in reply to Kavindu Dharmasiri
    TI__Genius 14890 points

    Kavindu,

    What can you tell me about the coil you are using on the receiver side?  What are its dimensions?  What is its inductance?  What sort of shielding does it have?

    Get some oscilloscope plots of the RECT pin.  This is an indication of the coupling you're getting between the TX and the RX.

    Regards,

    Dick

  • 0 in reply to Dick Stacey
    Prodigy 150 points
    Dick,
    I'm using vishay IWAS-4832FF-50 48mm × 32 mm and Ls = 10.72uf Ls'= 14.93uf i'm not using extra sheilding. How can i get a idea from the signal coming from the rect pin.
  • 0 in reply to Kavindu Dharmasiri
    TI__Genius 14890 points
    Kavindu,

    RECT is the rectified AC1/AC2 voltage. Once RECT achieves a certain level, it will power on the bq51013B. If that level is not achieved, the system will not power on. Look at figure 17 in the bq51013B datasheet. The dark blue line shows VRECT at power up. If RECT is notincreasing as shown, there is an issue with the coupling and the plot can indicate where to look.

    Regards,

    Dick
  • 0 in reply to Dick Stacey
    Prodigy 150 points
    Dick,
    I have a little question , what are the reasons for low voltage at Rect pin
    regards
    Kavindu
  • 0 in reply to Kavindu Dharmasiri
    Prodigy 150 points
    Dear Dick,

    The situation of my issue was changed.My receiver circuit worked about 1minute.First the LED of power out put lit correctly also the LED's of the charger circuit.But after few seconds all the LED's started to flicker then i removed the circuit from the transmitter.Next time i placed it on transmitter again and there was no respond of the receiver circuit. I'm really confused about the reason for this issue.Please guide me with this scenario.

    Thank you
    Regards
    Kavindu
  • 0 in reply to Kavindu Dharmasiri
    TI__Genius 14890 points

    Kavindu,

    We have used the coil you reference without issue.

    The RECT pin low voltage would be due to poor coupling between the RX and TX.

    For debugging, look at the RECT voltage again.  Check soldering of components.  Verify that the capacitors you used for each pin have a high enough voltage rating.  As noted in an earlier post, the capacitors touching AC1 or AC2 must have at least a 25V rating.

    What is the charge current setting?  Do you know if you were getting the correct charge voltage and current?

    Have you looked at the bqTESLA FAQ?  It is in the top section of the Wireless Power Forum section.

    Regards,

    Dick

  • 0 in reply to Dick Stacey
    Prodigy 150 points

    Dear Dick,

    Thank you for the tips.I'll check on the RECT pin with a oscilas scope and soldering.I have already used correct voltage ratings for the capacitors(50V). The charging current setting for the charging circuit is 150mA. I checked the voltage by applying voltage by DC voltage source only for the charging circuit and i got 4.198V stil i did't check the current. The circuit is tested without applying a load.The transmitter indicate the charge complete state after placing the Rx coil on the receiver.

    Thank you

    Regards

    Kavindu

  • 0 in reply to Kavindu Dharmasiri
    TI__Genius 14890 points
    Is it possible that the battery was fully changed and terminated the charge routine?
  • 0 in reply to Dick Stacey
    Prodigy 150 points

    Dear Dick,

    Sorry for the late reply i was working on my issue. Luckily thanks to your guidelines i was able to find the problem, it was bad soldering of the BQ51013B IC. Output of the Rx is About 4.9V and Output of the Charger circuit is 3.9V . For battery charger i'm using BQ24040. Also i attached the the outputs of RECT and OUT pins. Top one is the OUT waveform and bottom one is the RECT waveform. Please guide me.

    Thank you

    Kavindu

    2541.TIF

  • 0 in reply to Kavindu Dharmasiri
    TI__Genius 14890 points

    Kavindu,

    The plots of OUT and RECT look good.  The pulses on the RECT pin are an indication of the communication.  The DC level of RECT is about 7V which gives some insight into the power transfer level.  Figures 4 and 5 in the bq51013B datasheet show the RECT voltage as the load varies.

    What issues are you having now?  If the output of the charger is 3.9V, that seems like the battery is being charged.  What current level is seen?

    Regards,

    Dick

  • 0 in reply to Dick Stacey
    Prodigy 150 points
    Dick,

    The output voltage of the battery charger with out connecting the battery is 3.9V. I guess it should be 4.2V. What is the reason for this voltage drip.

    Thank you
    Kavindu
  • 0 in reply to Kavindu Dharmasiri
    TI__Genius 14890 points
    Kavindu,

    Check out the Battery Detect Routine section in the bq24040 datasheet.

    Regards,

    Dick
  • 0 in reply to Dick Stacey
    Prodigy 150 points

    Dick,

    Thank you for the guide lines. now i'm working on that.Recently i found that no load start up of my design is not matching with the no load start up given in the data sheet.In my design Vout is not established after stabilization of Vrect it is varying with the Vrect even at the start up.Start waveform is attached with this post

    Thank you

    Regards

    Kavindu

  • 0 in reply to Kavindu Dharmasiri
    TI__Genius 14890 points

    Kavindu,

    Something does not make sense on your plot.  The OUT voltage should not occur until after the RECT voltage goes through its power up and through thresholds. You have too much coupling between OUT and RECT it seems.

    Figure 17 in the bq51013B shows how the RECT powers up before OUT is turned on. In this case, the load is a resistor so as OUT turns on, both the voltage and current ramp.  The thresholds for RECT are shown in the section 7.5 under VRECT-Th1 throgh VRECT-Th4.

    Regards,

    Dick