Patent ID: 6771696
Filing Date: 2004-08-03
Classification: H04L

Abstract:
A combined modem and line-isolation system, comprising:a line-side line-isolation integrated circuit configured to be coupled to a phone line; a system-side line-isolation integrated circuit; digital signal processing (DSP) circuitry included within the system-side line-isolation integrated circuit, the DSP circuitry having a modem processor for modem data and a digital processor for system-side circuitry; a dc termination pin on the line-side line isolation integrated circuit, the line-side line-isolation integrated circuit configured to utilize the dc termination pin to provide proper dc termination characteristics to the phone line when the line-side line-isolation circuit is in an off-hook state; circuitry coupled to the dc termination pin and configured to cause a voltage at the dc termination pin to be proportional to a voltage on the phone line when the line-isolation integrated circuit is in an on-hook state; and circuitry within the line-side line-isolation integrated circuit coupled to the dc termination pin and configured to utilize the dc termination pin to monitor the voltage at the dc termination pin as a voltage representative of a voltage on the phone line when the line-side line-isolation integrated circuit is in an on-hook state, wherein the line-side line-isolation integrated circuit and the system-side line-isolation integrated circuit are capable of being coupled to an isolation barrier to communicate digital information with each other through the isolation barrier.