04021701 is referenced by 47 patents and cites 9 patents.

The disclosed protection circuit which is suitable for providing protection of transistors included in integrated circuits such as regulators and power amplifiers, includes thermal shutdown, safe area and current control circuits. The current control portion includes a sense transistor connected substantially in parallel with the transistor to be protected. In monolithic integrated circuit applications, the sense transistor has an emitter area that is a predetermined ratio of the emitter area of the protected transistor. A "sense resistor" is connected to the sense transistor and develops a control signal which is proportional to the instantaneous current being conducted by the protected transistor. A threshold circuit is coupled between the sense resistor and the drive circuit for the protected transistor and responds to the magnitude of the control signal crossing a predetermined threshold to remove or reduce the drive to the protected transistor.

Title
Transistor protection circuit
Application Number
5/638879
Publication Number
4021701
Application Date
December 8, 1975
Publication Date
May 3, 1977
Inventor
Robert Bruce Davies
Tempe
AZ, US
Agent
Maurice J Jones Jr
Assignee
Motorola
IL, US
IPC
H02H 7/20
View Original Source