Patent ID: 7983012
Filing Date: 2011-07-19
Classification: H04L,H05B

Abstract:
1. A communication circuit for a load control device, the load control device operable to be coupled to a communication link having two conductors, the load control device operable to transmit a digital message by alternating the communication link between an idle state in which a link voltage is developed across the conductors on the communication link and an active state in which the conductors of the communication link are substantially the same electrical potential, the communication circuit comprising: a receiving circuit coupled between the conductors of the communication link, the receiving circuit operable to conduct an idle current when the communication link is in the idle state; and a transmitting circuit coupled between the conductors of the communication link, the transmitting circuit comprising: wherein, when the communication link is in the idle state, the current source does not generate the source current; and wherein, when the controllably conductive device is electrically coupling the conductors of the communication link together, the output of the optocoupler is operable to conduct a first portion of the source current and the voltage clamp is operable to conduct a second portion of the source current, such that the phototransistor of the optocoupler is maintained in an active region of operation.