Title:
OUERHEAT PREVENTIVE TRIGGER CIRCUIT HAVING NARROW THRESHOLD FLUCTUATION RANGE
Document Type and Number:
Japanese Patent JPH02248113
Kind Code:
A
Abstract:
PURPOSE: To limit a range of fluctuation in a set intervention threshold by switching on a transistor(TR) when currents flowing to two base-emitter connections are equal to each other after a preset threshold temperature is reached. CONSTITUTION: A current 11 is substantially proportional to a VBE/R1 with a high temperature dependency, and a current 13 is proportional to a ΔVBE/R2 with a comparatively small temperature dependency, where R1 and R2 are resistance of two resistors whose value is set preliminarily as a function of other parameters to set a desired intervene threshold temperature and ΔVBE is a difference between base-emitter voltages of TRs 3, 4 to form an emitter degenerating current mirror. When currents flowing through two branches of current mirrors are equal to each other, a TR Q7 is conductive as a result of reaching the desired intervention threshold temperature. Then all integrated circuits over-heated in the usual intervention mode of an overheat prevention circuit are switched off.
Inventors:
BURUUNO MURAARI
ROBERUTO SORAARI
MATSUSHIMO NISETSUTO
ROBERUTO SORAARI
MATSUSHIMO NISETSUTO
Application Number:
JP4230790A
Publication Date:
October 03, 1990
Filing Date:
February 22, 1990
Export Citation:
Assignee:
SGS THOMSON MICROELECTRONICS
International Classes:
H02H5/04; H03K17/14; H03K17/08; (IPC1-7): H03K17/08; H03K17/14
Attorney, Agent or Firm:
Hiroyuki Mori
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