Patent Number: 6,396,315

Title: Voltage clamp for a failsafe buffer

Abstract: A voltage clamp for a failsafe buffer used in connection with an electronic device. The voltage clamp clamps a voltage present at the output terminal of the buffer only when the electronic device is powered-on, and present a high impedance when the electronic device is not powered-on. Thus, when an electronic device such as a printer, for example, is connected to a network and the device is in a powered-on state, the voltage at the output terminal of the buffer is clamped to approximately the value of the electronic device power source. When the electronic device is powered-off, a voltage present at the output of the buffer will not clamped by the voltage clamp. Instead, the buffer will present a high impedance to the network and to other electronic devices connected thereto. Consequently, when an electronic device having a failsafe buffer constructed in accordance with the present invention enters an inoperable state due to device failure, power loss, etc., yet remains physically connected to the network and to other electronic devices, the inoperable device will not affect operation of other devices connected to the network.

Inventors: Morris; Bernard Lee (Emmaus, PA)

Assignee: Agere Systems Guardian Corp.

International Classification: H03K 19/003 (20060101); H03B 001/00 (); H03K 003/00 ()

Expiration Date: 05/28/2019