BQ500110 coil_pwm problems

Hello Vladimir and thank you very much for your informative response.

Now that i know the BQ500110 seems to be switching the coil correctly, I have moved onto debugging the reviever side/communication channels.

When I first place my reciever on the transmit coil (there is about 5mm spacer between the coils) I get zero volts at the output of the receiver. when probing the V-RECT pin the voltage is varying about 500mV to 1V during the transmitter analog pings and rises to around 8 - 10V during the digital pings.

I probe the COMM1 and COMM2 pins on the 51013 receiver and they show a digital signal with 'spaces' as zero volts and 'marks' as a 175 kHz AC voltage (10 Vp-p). when I look at the COMM pins on the receiver I see some pre-amble followed by a header byte, then the message then the checksum as expected.This is shown in the following screen shot where the yellow trace is the COMM1 pin and the purple trace is the VRECT pin.

Probing the COMM1 and COMM2 pins on the 500110 shows about a 100 mVp-p with a DC offset of around 3.25 volts. Obviously my demodulation circuit is not working correctly. I have based this demodulaiton circuit off the BQ500110-EVM, what kind of signal should I expect to see at the COMM pins of the 500110 using this circuit?

One other thing I notice is that if I move the coils a tiny bit closer together (using a slightly thinner spacer) the status LED on the BQ500110 tranmitter starts blinking at a 200ms rate indicating a fault. After this the transmitter stops driving the TX coil until I reset the BQ500110.

If the communication demodulation circuit is not working correctly then why am I getting fault conditions on the transmitter only when I place the receiver on the transmitting coil? (almost seems as if the transmitter is getting a fault communication from the receiver). I've got PMOD disabled and the fault light doesn't blink if i place just an unconnected receiver coil on the TX coil.

Is there a way to determine the type of fault that is occurring (PLD, SYS, DEV or NVM)?

Is there any detailed information on the faults that are indicated by the BQ500110 LED status indicators (what exactly are the PLD, SYS, DEV and NVM faults)?

Sorry about the length of this question, once again any help would be greatly appreciated.

Just a follow up on the last post I made:

I fixed the errors I had with my demodulator circuit and the receiver is now communicating with the transmitter. The 500110 is no longer indicating faults when i place the receiver coil closer than about 5mm to the transmit coil.

The last problem with my BQ500110 circuit is that when I power it up, it doesn't initialize properly and an external reset must be performed to get the BQ500110 to enter standby mode. Is there any particular conditions that must be met while the IC is doing its initial POR/initialization (such as holding the external reset pin low until the initialization is complete)?

Cheers