JAJSVF7 October 2024 BQ51013C
PRODUCTION DATA
デバイスごとのパッケージ図は、PDF版データシートをご参照ください。
The WPC communication uses a modulation technique termed “back-scatter modulation” where the receiver coil is dynamically loaded in order to provide amplitude modulation of the transmitter's coil voltage and current. This scheme is possible due to the fundamental behavior between two loosely coupled inductors (here between the TX and RX coils). This type of modulation can be accomplished by switching in and out a resistor at the output of the rectifier, or by switching in and out a capacitor across the AC1/AC2 net. Figure 8-4 shows how to implement resistive modulation.
Figure 8-5 shows how to implement capacitive modulation.
The amplitude change in the TX coil voltage or current can be detected by the transmitter's decoder. The resulting signal observed by the TX is shown in Figure 8-6.
The WPC protocol uses a differential bi-phase encoding scheme to modulate the data bits onto the TX coil voltage/current. Each data bit is aligned at a full period of 0.5 ms (tCLK) or 2 kHz. An encoded ONE results in two transitions during the bit period and an encoded ZERO results in a single transition. See Figure 8-7 for an example of the differential bi-phase encoding.
The bits are sent LSB first and use an 11-bit asynchronous serial format for each portion of the packet. This includes one start bit, n-data bytes, a parity bit, and a single stop bit. The start bit is always ZERO and the parity bit is odd. The stop bit is always ONE. Figure 8-8 shows the details of the asynchronous serial format.
Each packet format is organized as shown in Figure 8-9.
Figure 7-20 shows an example waveform of the receiver sending a rectified power packet (header 0x04).