Title:
ELECTRONIC CIRCUIT, ELECTRONIC INSTRUMENT AND INTEGRATED CIRCUIT
Document Type and Number:
Japanese Patent JP2017219395
Kind Code:
A
Abstract:
PROBLEM TO BE SOLVED: To highly accurately implement diagnosis of sensors, using an output signal of an electrically heated wire type air flow rate sensor.SOLUTION: An air flow rate sensor 1 includes a heated wire measurement unit 2 and an electronic circuit 3. The heated wire measurement unit 2 includes a first circuit C1 and a second circuit C2 that are connected in parallel with each other with regard to a transistor Q1 to be connected to a voltage source. Each of the first circuit C1 and the second circuit C2 includes two resistance elements to be series connected. An electrically heated wire HW is included in the first circuit. The electronic circuit 3 comprises: an amplification unit that implements feedback control of supply power to the electrically heated wire HW in an equilibrium state where a voltage Va at an intermediate point of the first circuit C1 coincides with a voltage Vb at an intermediate point of the second circuit C2; a computation unit 20 that computes an output signal indicative of an air flow rate, using the voltage Va; and a voltage fixation unit 30 that, in responce to reception of a self diagnosis request from an outside, fixes the voltage Vb to a reference voltage VREF higher than the maximum value of the voltage Va.SELECTED DRAWING: Figure 1
Inventors:
MISHIMA KAZUMA
Application Number:
JP2016113321A
Publication Date:
December 14, 2017
Filing Date:
June 07, 2016
Export Citation:
Assignee:
ROHM CO LTD
International Classes:
G01F1/696; G01F1/69
Attorney, Agent or Firm:
Fukami patent office
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