Schaltung zur Leistungsabgabe mit Stromerfassung

摘要

A power delivery circuit for supplying load current to a load includes a current switch connected on the high potential side of a load. In order to detect a current condition, such as an over-current condition in the load, a current sensing and detection circuit preferably cooperates with the current switch wherein such switch comprises a multicellular device with a plurality of terminals. Such terminals include a first main current terminal connected to a source of high potential, a second main current terminal connecting a majority of device cells to the load, a first auxiliary terminal connected at one end to a minority of device cells so as to provide a current generally proportional to the main device current, and a second auxiliary terminal connected at one end to a majority of device cells. The current detection circuit preferably comprises one branch connected between the first auxiliary terminal and ground and including, in serial circuit, a current-to-voltage converting resistor providing a voltage at one end approximately proportional to the main device current and a bias signal-controlled transimpedance device, and another branch connected between the second auxiliary terminal and ground and providing a bias signal for the transimpedance device in the first branch. In another embodiment, the first branch includes at least two transistors and a resistor serially connected between a current sense terminal of the MOSFET and a reference potential. The second branch also includes at least two serially connected transistors connected between a terminal of the MOSFET and the reference potential. The transistors are cross-connected between branches and provide an inverted current mirror and a current mirror. Fifth and sixth transistors may also be included as part of the current sensing circuit.