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BQ51050B: Schematic review for Compact wireless receiver made from BQ51050B and TPS63051 Buck-Boost 3.3V regulator

Muhammad Akram Karimi
Prodigy 245 points
Part Number: BQ51050B
Other Parts Discussed in Thread: TPS63051, , BQ50002A, BQ500511A

Dear All,

I am working on this building a simple and compact wireless receiver using BQ51050Band trying to get the regulated 3.3V using TPS63051. I have also built a PCB but I am not getting any output on BAT (pin4) of BQ51050Q and neither on Vout (pin4) of TPS63051.
Here is the schematic of BQ51050B

Charging current has been set to 500mA and 10% termination current.

BAT voltage is being regulated using TPS63051 as shown in schematic below:

I am using 732-6211-ND coil (7.5uH) from digikey as a receiver coil.

On the transmitter side, I am using standard BQ50002EVM-607 from TI and I did not do any changes on Tx side; just supplied it with 5.0V supply and testing with the receiver (schematic shown above).Please note that I have not connected any battery on BAT terminal? Does it make any difference? Also if the L' is not properly calculated; the values of C1 and C2 might be wrong; so how big a difference should it make on the performance.

Any suggestions how to proceed with the debugging?

I will be really obliged if someone takes his time to review and let me know why the Rx circuit is not working.

Thanks

  • 0
    TI__Guru 65706 points
    Schematic looks OK
    Recommend testing with a battery or battery emulator.
    Send scope capture of the Voltage at RECT (Pin 18)

    "Please note that I have not connected any battery on BAT terminal?"---This will cause start up problem for the bq51050B, needs to see a battery to start and continue to operate.

    "Also if the L' is not properly calculated; the values of C1 and C2 might be wrong; so how big a difference should it make on the performance."---The value needs to be close. Value on the Coil data sheet is free space (L) with nothing around it, when placed on the TX coil (L') value will change and tuning will change. See measurement and tuning procedure in the data sheet. "Series and Parallel Resonant Capacitors Section".
    The Cd (C13 and C14) are only used with a moving coil TX not bq50002A TX.

    "Any suggestions how to proceed with the debugging?"----Take a look at the FAQ section, one presentation is on TX troubles shooting and it has start up waveforms for the RX.
  • 0 in reply to Bill Johns
    Prodigy 245 points

    Dear Bill,

    Thanks for your response. I will put a 3.7V Li-Ion battery (with charge current limit of 1.0A) on BAT terminal and will put a small load of around 50-100mA let's say when testing next time. I will send you the scope captures as well.

    Can you please tell me what do you mean by moving coil Tx ? Don't I need C13 and C14 with BQ50002A TX?

    Should I remove it or it does not make any difference?

    Can you also send me the link of the troubleshooting presentation which has waveform which I should expect on my RX 51050B chip?

    Thanks

  • 0 in reply to Muhammad Akram Karimi
    TI__Guru 65706 points

    Link to Wireless Power E2E FAQ is below also see FAQ tab in the forum screen on right side.

    e2e.ti.com/.../wireless_power_faq

  • 0 in reply to Bill Johns
    TI__Guru 65706 points

    Wireless Power RX coil tuning
    All new receivers will require verification or tuning of the Cs (resonant capacitors) and Cd (detection capacitors).
    See receiver data sheets "Series and Parallel Resonant Capacitor" for tuning instructions.
    A couple of notes on this:
    1.) The RX coil L is affected by the final design case. The metal around and behind it such as battery will change the L.
    2.) Tuning does not need to be done on each unit, typical production runs see little change and are consistent over the build.
    3.) For Qi certification this tuning must be done.
    4.) The Cd capacitors are use for moving coil type transmitters in the WPC standard, see QE-TM101. For non-Qi certified units the Cd value is less important.

  • 0 in reply to Bill Johns
    Prodigy 245 points

    Dear Bill,
    Thanks for your reply.
    Here is the update:

    1. I have tested the PCB made using the schematic shown above
    2. I heard a beep sound from BQ50002EVM-607 and then D6 (yellow) LED started flashing for few seconds (around 5-10 seconds). During this period of time LED on my RX is also on
    3. After that D6 stopped and D5 (red) on EVM turned on permanently. LED on Rx also turned off.
    4. One thing which I noticed is that Both the BQ51050B and TPS63051 ICs turned extremely hot. My charge current is 500mA. Is it because of this high charge current?
    5. Voltage of the battery (3.7V Li Ion) instead of increasing; decreased by few mV. Something is wrong.

    Can you please suggest what the problem might be?
    Thanks

  • 0 in reply to Muhammad Akram Karimi
    Prodigy 245 points

    Following the previous update:

    I have got the scope captures (Please note that I have decreased the I-BULK to 300mA only and the Li-ion battery is empty when I started charging):

    1. Vrect and Vbat

    Vrect temporarily drops after an interval of few seconds and then drops for good as the D5(RED) error led lights up.

    Vbat does not rise up to a decent voltage level

    2. Here is the capture of V_RECT and V_TS/CTRL

    V_RECT and V_TS/CNTRL drops as D5 (RED) LED lights up which I think confirms the TS_GND error.

    I have used 10k resistor to GND on this pin.

    Can you please suggest what the problem might be.

    Thanks

  • 0 in reply to Muhammad Akram Karimi
    TI__Guru 65706 points

    Info on the bq50002A EVM LED indications.

    •D1- Green – Input 5V applied to unit

    •Behavior of LED D6, D5 and D4 determined by LED_MODE resistor.
    •LED_MODE – R25 24.9k ohms for Mode 1 (LED Control Option 1), see table 1 bq500511A Data Sheet.
    •D6- Green Power Transfer (LED_A) Pin 11
    –Power Transfer—Slow Blink at 1.25Hz rate
    –Charger Complete—On
    –DPL—Slow Blink at 1.25Hz rate. DPL is a reduced power mode due to low input voltage. See data sheet for more info.
    •D5- Red Fault (LED_B) Pin 12
    –Fault —On
    –FOD Warning—Fast Blink at 5Hz rate
    •FOD Warning is a 10 sec indication that FOD Loss exceeds fault threshold, fault will be set after 10 sec.
    –DPL—Slow Blink at 1.25Hz rate. DPL is a reduced power mode due to low input voltage. See data sheet for more info.
    •D4- Orange (LED_C) Pin 14
    –Not used in Mode 1
  • 0 in reply to Bill Johns
    TI__Guru 65706 points
    It is possible you are tripping FOD fault.
    Couple of things to try:
    1.) Disable FOD -- on the TX pull FOD_THR pin to 3V, short across R23
    2.) Increase RX Reported Power--(RX side) determined by resistor from FOD pin to ground. Increase value of resistor R2.
    3.) Increase TX FOD Threshold--(TX side) increase voltage at FOD_THR, see bq500511A data sheet "Foreign Object Detection (FOD)" section.

    When the unit is working FOD on the RX will need to be set.
  • 0 in reply to Bill Johns
    Prodigy 245 points

    Dear Bill,

    I have tried all of your suggestions:

    1. Disabled FOD on Tx side by shorting R23 using 0ohm resistor.

    2. I increased Rfod from 140 to 300 to 430 to 1000 ohm.

    But the tripping problem persists.

    Also in one of your posts you had mentioned that if FOD error is about to occur; RED LED flashed on/off but in my case it turns on once and remains on when the power transfer is cut.

    Please help me in debugging the problem. I really need to get it working.

    Thanks

  • 0 in reply to Muhammad Akram Karimi
    TI__Guru 65706 points
    I have replied to your other post. In addition to the info requested in that post.
    Can you provide layout files and photo of tests set up.
  • 0 in reply to Bill Johns
    Prodigy 245 points
    I have sent you the layout files in the message and on the other post as well.
    I will also send you the test setup picture as well.

    Thanks