Digital access arrangement circuitry and method having current ramping control of the hookswitch
First Claim
1. A method of controlling the current change in phone line side circuitry, comprising:
- providing a signal indicative of a desired change of a hookswitch from an off-hook state to an on-hook state; and
adjusting downward the current drawn from a phone line in response to the signal prior to changing the hookswitch from the off-hook state to the on-hook state.
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Accused Products
Abstract
A digital direct access arrangement (DAA) circuitry may be used to terminate the telephone connections at the user'"'"'s end to provide a communication path for signals to and from the phone lines. Briefly described, a means for providing a proper hookswitch transition for a variety of international phone standards is provided. The invention may also be utilized with means for transmitting and receiving a signal across a capacitive isolation barrier. More particularly, a DAA circuitry may be utilized which satisfies many or all hookswitch transition standards without the use of additional discrete devices. The hookswitch transition standards may be satisfied by ramping down the current flowing through the hookswitch prior to transitioning the hookswitch state. In this manner the hookswitch current change as a function of time (di/dt) may be decreased. Thus, the current through the hookswitch may be actively controlled prior to switching the hookswitch from an off-hook condition to an on-hook condition. By controlling the current drawn from the phone lines through the hookswitch, the maximum voltage seen at the phone company exchange may be decreased.
46 Citations
7 Claims
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1. A method of controlling the current change in phone line side circuitry, comprising:
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providing a signal indicative of a desired change of a hookswitch from an off-hook state to an on-hook state; and adjusting downward the current drawn from a phone line in response to the signal prior to changing the hookswitch from the off-hook state to the on-hook state. - View Dependent Claims (2, 3, 4)
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5. An integrated circuit compatible with a plurality of phone line standards having hookswitch transition requirements, the integrated circuit comprising:
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a node carrying a hookswitch signal; and at least one current control circuit coupled to the node to receive the hookswitch signal, the current control circuit coupled to at least one output of the integrated circuit, the current control circuit operating prior to the completion of a hookswitch transition to enable a decrease in a current level drawn from the phone line. - View Dependent Claims (6, 7)
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Specification