Gating circuit having current measuring and regulating elements and a temperature measuring transistor

US5841312A · kind A · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Anton Mindl · Hildesheim, DE
• Hartmut Michel
• Bernd Bireckoven · Tübingen, DE
• Manfred Uebele · Reutlingen, DE
• Ulrich Nelle · Mössingen, DE

Key dates

• Filing date: Jul 1, 1996
• Grant date: Nov 24, 1998
• Expiry date: Jul 1, 2016

Classification

• Technology area (CPC H): Electricity
• CPC primary: H03K2017/0806
• WIPO field: Basic communication processes
• WIPO sector: Electrical engineering

Abstract

The gating circuit has a power transistor (T1, T2, T3) and a current measuring resistor (R5) connected with the power transistor so that a voltage drop at the measuring resistor is a measure of a current flow in the power transistor. This voltage drop is used to trigger a current regulating transistor (T5) and a temperature measuring transistor (T9). Below a predetermined temperature, the current flow is limited solely by the current regulating transistor (T5). Above this predetermined temperature the collector current is further reduced via the temperature measuring transistor (T9) and a further transistor (T10) so as to protect the power transistor from thermal overload.