| 摘要 |
PROBLEM TO BE SOLVED: To eliminate a spike-shaped voltage to prevent the malfunction of an operational amplifier. SOLUTION: First and second resistors R1 and R2 are connected in series between one end of a shunt resistor SH of a current detection circuit CD and the reversal input terminal of an operational amplifier A, third and fourth resistors R3 and R4 are connected in series between the other of the shunt resistor SH and the non-inverted input terminal of the operational amplifier A, first and second diodes D1 and D2 are connected in series between a positive power supply and the ground, the connection point of the diodes D1 and D2 is connected to the connection point of the first and second resistors R1 and R2, third and fourth diodes D3 and D4 are connected in series between the positive power supply and the ground, and the connection point of the diodes D3 and D4 is connected to that of the third arid fourth resistors R3 and R4. At this time, the resistance value of the first resistor R1 is set so that a voltage being less than the operating voltage is applied to the first and second diodes D1 and D2, and at the same time is set to a smaller value than that of the second resistor R2. The resistance value of the third and fourth resistors R3 and R4 is also set similarly. |
