However, the similarities stop at this point. From the single ended side there are two pins that aren’t in most RS-485 Transceivers. The F_SET pin is used to select the carrier frequency of the OOK modulation; a resistor to ground will set the value of the carrier frequency – the tables for the 8000 and 8010 are shown in Table 2-1 and Table 2-2 respectively.

For best data integrity have the data rate be at least 10 times lower than the carrier frequency. So, if a 125KHz carrier signal is used the data rate should be no faster than the 12.5 Kbps. Higher carrier frequencies also can enable smaller capacitors and inductors in other parts of the circuit reducing board space needed. Next is the MODE pin – this acts as one enable for the device – a low level means the device is in RX mode while a high signal signifies the device is in TX mode.

On the differential communication side, the differences come down to two items. The first is that polarity is now unimportant as the THVD8000/8010 when receiving data reads active pulse trains as 0’s and no active signals a logic 1 so a polarity flip between A and B will not interfere with communication. The second is that transition times and mode change delays are related to the carrier frequency chosen this along with the extra modulation and demodulation circuitry can cause this device to not reach as high of data rates, but with the benefit of transferring data over power lines.