| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain the amount of drive current that flows through a heater 10 in a fuel injection system without using a current detection resistor. <P>SOLUTION: A heater control circuit for controlling the heater 10 includes: an nMOS transistor 20 located between a power source Vdd and the heater 10; a microcomputer 30 for controlling the nMOS transistor 20 such that current flows between the power source Vdd and the ground through the heater 10 and the nMOS transistor 20; and a nonvolatile memory 40 for storing a value of ON-resistance of the nMOS transistor 20 when the current is allowed to flow through the heater 10 and the nMOS transistor 20 by the microcomputer 30. The microcomputer 30 obtains a voltage difference (V<SB POS="POST">A</SB>-V<SB POS="POST">B</SB>) between a point A 21 and a point B 22, and computes the current which flows between a drain and source of the nMOS transistor 20 as drive current that flows through the heater 10 by using the obtained voltage difference (V<SB POS="POST">A</SB>-V<SB POS="POST">B</SB>) and the ON-resistance stored in the nonvolatile memory 40. <P>COPYRIGHT: (C)2013,JPO&INPIT |
