Abstract: A regenerative current detection circuit includes a first power MOS transistor that is configured as a current mirror to a second power MOS transistor connected to drive a motor winding, a first feedback amplifier that compares a first regenerative current that flows in the first power MOS transistor with a second regenerative current that flows in the second power MOS transistor and outputs a comparison result, the first regenerative current being obtained by multiplying the second regenerative current by a current mirror ratio, and a current detection circuit that outputs a detection current based on the comparison result.

Abstract: A regenerative current detection circuit includes a first power MOS transistor that is configured as a current mirror to a second power MOS transistor connected to drive a motor winding, a first feedback amplifier that compares a first regenerative current that flows in the first power MOS transistor with a second regenerative current that flows in the second power MOS transistor and outputs a comparison result, the first regenerative current being obtained by multiplying the second regenerative current by a current mirror ratio, and a current detection circuit that outputs a detection current based on the comparison result.

Abstract: A withstand voltage of the LED driver circuit is set to be lower than an LED power supply voltage of the power supply and be higher than a first voltage value obtained by subtracting a voltage drop across whole of the LEDs connected in series caused by the second constant current from the LED power supply voltage. When raising a luminous intensity of the LEDs, in response to the control signal, the control circuit controls the switch circuit to bring about conduction between the LED drive terminal and the first switch terminal to let the first constant current flow through the LEDs. When lowering the luminous intensity of the LEDs, in response to the control signal, the control circuit controls the switch circuit to bring about conduction between the LED drive terminal and the second switch terminal to let the second constant current flow through the LEDs.

Abstract: A withstand voltage of the LED driver circuit is set to be lower than an LED power supply voltage of the power supply and be higher than a first voltage value obtained by subtracting a voltage drop across whole of the LEDs connected in series caused by the second constant current from the LED power supply voltage. When raising a luminous intensity of the LEDs, in response to the control signal, the control circuit controls the switch circuit to bring about conduction between the LED drive terminal and the first switch terminal to let the first constant current flow through the LEDs. When lowering the luminous intensity of the LEDs, in response to the control signal, the control circuit controls the switch circuit to bring about conduction between the LED drive terminal and the second switch terminal to let the second constant current flow through the LEDs.

Abstract: A constant current circuit delivering a constant current to a load connected between first and second output terminals comprises, a reference current generator configured to generate a reference current, a current mirror circuit configured to amplify the reference current, an output transistor configured to deliver the constant current based on an output of the current mirror circuit, a signal source configured to deliver a pulse control signal, an auxiliary switching circuit having a switch terminal configured to deliver a switch signal in response to the pulse control signal, and a discharge terminal configured to deliver a discharge signal to the current mirror circuit when the switch signal is stopped; and a switch circuit configured to turn off the output transistor with receiving the switch signal.

Abstract: A constant current circuit delivering a constant current to a load connected between first and second output terminals comprises, a reference current generator configured to generate a reference current, a current mirror circuit configured to amplify the reference current, an output transistor configured to deliver the constant current based on an output of the current mirror circuit, a signal source configured to deliver a pulse control signal, an auxiliary switching circuit having a switch terminal configured to deliver a switch signal in response to the pulse control signal, and a discharge terminal configured to deliver a discharge signal to the current mirror circuit when the switch signal is stopped; and a switch circuit configured to turn off the output transistor with receiving the switch signal.

Abstract: In a source-type constant current driver circuit for driving an LED, a current of 1/&bgr; times a reference current is generated from a base current of a transistor Q2 for generating the reference current by means of the current mirror circuit composed of a transistor pair Q1a, Q1b. Further, the current generated by the current mirror circuit is amplified by a factor of n by means of a current mirror circuit composed of a transistor Q3 and one of transistors Q5a to Q5h. Then the amplified current is supplied to a base current of a transistor Q8. Thus, a base current of the transistor Q8 in a final stage is controlled.