BQ51003: How to tune resonant capcitors value.

Prodigy 90 points
xiaoyan Yun

Part Number: BQ51003

Hello. 

I found a equation on bq510003 datasheet on page 27.  if use fs=10KHz, fd=1MHz, and Ls value is fixed. therefore C1, C2 will be worked out. 

But I use EVM parameter Ls=10uH to work out C1,  get C1= 3900000F. it doesn't match EVM C1=68nF + 68nF +47nF = 183nF. 

Could you please check it and give me a explaination. thank you!

Any side, I didn't find the equation on TX chip datasheet (bq50002A). how to work out TX resonant capcitors?  

Prodigy 90 points
xiaoyan Yun
  • Mastermind 21415 points
    Bill Johns
    Hello
    On data sheet page 27 equation 6 shows fs = 100kHz and fd = 1MHz. I do not see fs=10kHz.

    For C1 calculation the Ls' value should be used. This is measured with the coil mounted on a TX coil simulator , Fig 34.
    Ls' will be higher than free space inductance Ls used for calculation for C2 (Cd).

    For BQ51003 the Ls' value measured 13.5uH, this will calculate a value for C1 187nF, in the ckt C1/C2/C3 is 68nF/68nF/47nF = 183nF.

    The TX side is set by WPC standard for A11 TX. The L value is set at 6.3uH and resonant caps are set at 400nF.

    Best Regards,

    Bill Johns,  Applications Engineer

    Texas Instruments Inc

    Dallas, Texas

    Note:  If this answer solves your question please click the "Verify Answer"  button.

All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with respect to these materials. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.

Content on this site may contain or be subject to specific guidelines or limitations on use. All postings and use of the content on this site are subject to the Terms of Use of the site; third parties using this content agree to abide by any limitations or guidelines and to comply with the Terms of Use of this site. TI, its suppliers and providers of content reserve the right to make corrections, deletions, modifications, enhancements, improvements and other changes to the content and materials, its products, programs and services at any time or to move or discontinue any content, products, programs, or services without notice.

TI Worldwide | Contact Us | my.TI Login | Site Map | Corporate Citizenship | mobile m.ti.com (Mobile Version)

TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs and
embedded processors, along with software, tools and the industry’s largest sales/support staff.

© Copyright 1995-2017 Texas Instruments Incorporated. All rights reserved.
Trademarks | Privacy Policy | Terms of Use