SSC P485 PL Transceiver IC

July 1998

7

Revision 5

24000828

ADVANCE INFORMATION

SSC P485 Power Line Interface

Analog data is transferred between the communication medium and the SSC P485 over the Signal In (SI) and

Signal Out (SO) pins (refer to Figure 5). When transmitting, SSC “chirps” from the SSC P485 SO pin are filtered

by the output filter to remove harmonic energy (distortion) from the transmit signal and then amplified by the SSC

P111 Power Line Media Interface IC. The SSC P111 is a high-efficiency amplifier and tri-state switch specifically

designed for use in power line network systems. The amplifier is powered down and its output set to a high

impedance condition when the SSC P485 TS* signal is logic low, isolating the amplifier from the receive circuitry

and reducing node power consumption during receive operation. When the SSC P485 TS* signal is logic high,

the communication signal is routed to the communication medium through the coupling circuit (capacitor or

transformer). When receiving, the communication signal passes through the coupling circuit and is filtered by the

bandpass input filter. The resulting signal is then applied to the SSC P485 SI pin for processing. Refer to the

application reference shown in Figure 14.

Host micro with

internal UART

ILD

RXD

TXD

P485

IC

P111

IC

SO

TS*

SI

ILD

DI

RO

Single

Wire

input

filter

output

filter

medium

coupler

Figure 5. SSC P485 Medium Coupling

SSC P485 Message Format

The P485 requires the following message formatting:

Start bits

1, logic low

Data bits

8 or 9 (default 8)

Stop bits

1, logic high

Character gap

0-4 bit times

Message gap

12 bit times minimum

Message length

1 character minimum