• State Resolved
  • Locked Locked
  • Replies 7 replies
  • Answers 2 answers
  • Subscribers 64 subscribers
  • Views 1200 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.

BQ51003: Immediate help required confirming the design

Srujana Patel
Prodigy 250 points
Part Number: BQ51003
Other Parts Discussed in Thread: BQ24040,

Hello,

As you can see in the attached image, I used a capacitance of 10uF and 4.7uF at RECT and 2.2uF at OUT. I considered these values following the schematics document that is given in project design files in TI website.  I expect an output of 400mA at the Receiver end. But, the values that mentioned in the specifications document are completely different. I want to confirm if I can expect an output of 400mA at this receiver end using the above-mentioned values for RECT and OUT capacitors. Please check the values given in the attached image.

Also, the RECT and OUT bypass capacitors are at a distance as displayed in the second image. Would this anyway affect my output? Here, C12, C13 are my RECT capacitors and C15 is the OUT bypass capacitor.

Thank you in advance.

Best Regards,

Srujana Patel.

  • 0
    Prodigy 250 points
    Hello,

    I am sorry to bother but the above-mentioned issue is a bit critical and I expect a response sooner from any Applications Engineer. The design is ready for production. So, your comments would be very important.
    Thank you in advance.

    Best Regards,
    Srujana Patel.
  • 0 in reply to Srujana Patel
    TI__Guru 71166 points
    An output capacitor of 2.2uF is OK, the Rect cap of 10uF and 4.7uF are OK.
    Rect will have the higher noise and closer postion of the filter cap will help, if the 4.7uF cap could be closer that would help also.
  • 0 in reply to Bill Johns
    Prodigy 250 points

    Thank you so much for the response. Could you please check and let me know if all the other details are fine as well? Here, I expect a current output 400 mA at the out pin of BQ51003 and an output of 265mA at out pin of BQ24040.  

    Please find the attached schematic for a clear picture of values used. 

  • 0 in reply to Srujana Patel
    Prodigy 250 points

    Hello,

    Could you please check the above design for the above-mentioned requirements of output. I would like to confirm the model as it is sent for production in volume.

    Thank you in advance.

    Best Regards,

    Srujana Patel.

  • 0 in reply to Srujana Patel
    TI__Guru 71166 points

    Hello

    Review of schematic:

    1.) Cs tuning capacitors, C7, C9 and C8 -- total value of 38nF will require a coil with Ls' of about 68uH to meet tuning requirement

    2.) If tuning value is 38nF may need to reduce COMM 1 / 2 cap from 22nF to about 10nF

    3.) Current limit set by R4, R9 R3 -- total 662 ohms for about 400mA (OK).

    4.) FOD resistor R2, R4, R9 -- set during FOD calibration, OK for now.

    5.) C-Rect and C-Out OK

    6.) ISET--- fast charge current 265mA

    7.) Preterm---termination 20% of 265mA, about 50mA

    8.) ISET2--Gnd current limit set to ISET value.

    9.) TS--Looks ok

    Couple of things to check on -- What is the voltage rating of CS, C9, C8 and C7.  Also BOOT, COMM and CLAMP caps?

  • 0 in reply to Bill Johns
    Prodigy 250 points
    Hello,

    Thank you for the response.
    Yes, I have a coil of that measures Ls' of 66 uH capacitance and hence I calculated and achieved Cs value to be 38 nF.
    So, as per your suggestion I shall reduce the capacitance values of COMM1 and COMM2 to 10nF.
    The selected CLAMP,COMM and BOOT capaitors i.e., C1,C2,C3,C4,C5 and C6 have a voltage rating of 25V. This voltage rating is selected as per the datasheet of BQ51003. Is this okay?
    The selected resonant tank capacitors i.e., C7, C8, C9, C10 and C11 have a voltage rating of 50V. Is this fine?

    Waiting for a quick response.

    Thanks & Regards,
    Srujana Patel.
  • 0 in reply to Srujana Patel
    TI__Guru 71166 points
    This looks OK.