Hi,
I have a wireless receiver using BQ51051B for charging a 300/200mAh Li Po battery and a wireless coil of 15.6uH (Ls') (measured with the help of LCR ammeter in a final arrangement). I am sharing the schematics we have used in our setup. The transmitter being used is BQ500410 EVM from TI. The final circuit can draw up to a maximum of 120mA while operation. The coil is getting detected as I can hear the buzzer of TX EVM beep every time I place the receiver coil on top. Even the LED glows on and off which is an indication of power transfer. The battery gets drained instead of charging. Please clarify the following for me and help me identify the mistake I am doing in this.
- We want wired and wireless charging in our setup. When there is no valid input to AD line, the wireless charger should be working right (capable of charging battery)?
- How can I find if the battery is charging or not?
- I tried the custom coil with BQ51050B EVM and it works without changing the tuning circuit, so can I rule out the possibility of mismatch in tuning from custom board? (I even tried replacing the capacitors in custom board, no luck. When I measure voltage at AC1, AC2 of RX, I can see 3.0 -3.3V, which I presume is more than enough to start working
- When I probe RECT line of RX at C33 in my schematic, I get voltages varying from 4.3 to 5.02V, but nothing higher than this? Can I increase the RECT voltage seen by the RX?
- As per battery specifications shared by our battery manufacturer, safe charging limit is 0.2C and when computing using equation 1, i am getting a charging current limit of 80mA for 3.83K. Is this value ok for charging current, as our initial assumption was charging current is not enough as the load keeps on draining something like 60mA constantly. To verify the same, we changed target board configuration and kept it in a low power mode consuming nearly around 6mA, still battery is draining at a slower rate
- How can I sniff the packets transferred between receiver and transmitter?
- When I probe using scope at AC1 line of TX EVM, I can see the digital ping at 175KHz, but at RX end, the voltage level is too small, but frequency remains somewhat same.
Please help me with this and do guide me with insights which can get this setup working.
