Silicon Laboratories Inc.
POWER TRANSISTOR DETECTION WITH SELF-PROTECTION

Abstract:

A method for establishing a powered link over a transmission line includes enabling a current source to provide a constant, predetermined current to a terminal. The method includes sensing a voltage on the terminal to generate a sensed voltage level. The method includes comparing the sensed voltage level on the terminal to a predetermined voltage level. The method includes disabling the current source in response to the sensed voltage level equaling or exceeding the predetermined voltage level. The method may include, while the current source is enabled, a power transistor coupled to the terminal is disabled and only conducts current in a subthreshold region of transistor operation.