bq51013B Schematic and PCB layout

Eduardo,

Can you send the schematic and PCB layout in PDF form?

I have a few comments about the schematic.  

The resonant capacitors (C9, C10 and C11) will need to be tuned based on the system you create and the specific coil you choose.  See the datasheet section "Series and Parallel Resonant Capacitor Selection" for more details.  In this section, the value of "C1" corresponds to your C9, C10 and C11.  The "C2" would be your C7 and C8.

The values for R5 and R6 depend on your choice of the NTC (R7).

What is your intended nominal current (and maximum current)?

For the layout (which I have not been able to view), I would also suggest having the ability to use 2 (or maybe 3) resistors in place of your R1 (FOD) and R4 (ROS).

Regards,

Dick

Hi Dick, 

Here is the PCB layout. I could probably also export it to gerber files if the format is an issue. 

My plan with this is, at first, to just shrink the EVM down and get it working with a custom PCB. Something like a first approach to designing a receiver and getting it to work. Afterwards I would then start making changes and adapting it to my very specific needs. I also plan to do the same with the bq51050B. For now, I would like to be able to get up to 1A max current out of it. 

Resonant Capacitors: I'm aware that these have to be tuned. The problem is that the LCR meters capable of measuring at 100kHz seem to be a little bit to expensive for a hobbyist like me. Would measuring at 10kHz be an acceptable (good-enough / hobby level) solution ? Nevertheless, in order to avoid the tuning I plan to use the same coil and caps as in the EVM. This should work,right? 

You were right about the NTC resistor values, I had them wrong.

What exactly do you meen with having various resistors in place of R1 and R4?  

Oh, and one other question about the EVM-764: What's the effect of changing the pull-up from Vz (Rect) to Out? How does it affect the modules behavior? 

Thank you for your time!

Eduardo,

Using the same coil as the EVM should be a good start with the resonant capacitors.  They key to the 100kHz tuning is not simply to measure the inductance, but to set the resonant frequency at 100kHz.  This allows the system to operate in it's optimum range.  The goal is to keep the device operating in a frequency range that allows for decreasing power at higher frequencies and increasing power at lower frequencies.  If the system frequency range has the resonant frequency in its intended operating range then changing frequency might not get the expected change in power delivery.  All that said, using the EVM values as you stated should keep you in a reasonable range.

The FOD calibration is a very involved process.  For your system, it might be best to just use the values in the EVM (as you've shown in your schematic).  My note meant that if you did calibration and needed a non-standard resistor value for R1, you might need two standard resistor values in series.  Similar for R4.  

I expect your question on the pull-up is related to EN1/EN2 for pull-up.  D2 on the pull-up is there to protect the EN pins from the higher voltages possible on RECT.  RECT is available before OUT (hundreds of milliseconds). If you use OUT for the pull-up you can save a D2, but then EN (if pulled high) is not high until OUT goes high.

It will take me a bit to review the layout.

Regards,

Dick

Ok, thanks on the feedback. I will be adding one or two 0-Ohm resistors in series with R1 and R4, just in case.