The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 04, 1999
Filed:
Jun. 27, 1997
Satoshi Furuno, Nakasma, JP;
Rohm Co. Ltd., Kyoto, JP;
Abstract
A protection circuit for a pnp-type output transistor includes a pnp-type monitor transistor through which a current 1/n (where n>1) times as high as the output current of the output transistor passes. A first, second, and third resistor are connected between the output electrode of the output transistor and ground. An output terminal is connected to the collector of the output transistor. A fourth and fifth resistor are connected serially between the output current of the monitor transistor and ground. When the voltage at the node between the fourth and fifth resistors exceeds a predetermined level, the conduction biases for the output and monitor transistors are reduced. When the voltage at the node between the first and second resistors drops below the voltage at the output side of the monitor transistor, the conduction biases are further reduced in accordance with the voltage difference.