Device for electrical and/or electronic telephone circuits, designed to limit the power dissipated within them

摘要

A protection device, for a telephone (or other load) 27 in series with an external protection transistor 2, includes a sensor 6 for detecting common-mode current into the load. The output of the sensor 6 is connected to affect a current source/sink combination, and imbalance in this source/sink combination produces a voltage shift which is indirectly connected to control the protection transistor.