| 摘要 |
<P>PROBLEM TO BE SOLVED: To precisely detect a current in both on and off command periods without interposing a transistor for current detection in series with a load. <P>SOLUTION: In an on command period, a sense transistor 23 detects a load current. In an off command period, a controller 25 uses detected current values at two or more time points acquired in the on command period to calculate time constant information about a linear solenoid 2 under a known supply voltage VB, and computes a load current in the off command period based on the time constant information, the current in the on command period detected before the transition to the off command period, and the supply voltage VB. A comparator 24 compares an output voltage Vout with a reference voltage Vref in the off command period, and the controller 25 detects an open failure of a freewheel diode 6 according to the comparison result. <P>COPYRIGHT: (C)2012,JPO&INPIT |
