Patent ID: 8044652
Filing Date: 2011-10-25
Classification: G05F

Abstract:
1. A constant current control circuit coupled with a first external load and a second external load, the constant current control circuit comprising; a power supply terminal that a power supply voltage is applied to; a first semiconductor switching element that is connected with the power supply terminal and controls a first constant current, the first constant current flowing toward the first external load based on the power supply voltage; a second semiconductor switching element that is connected with the power supply terminal and controls a second constant current, the second constant current flowing toward the second external load based on the power supply voltage; a first output terminal that is connected with the first external load; a second output terminal that is connected with the second external load; a first shunt resistor that is connected between the first external load and the first semiconductor switching element, and detects the first constant current; a second shunt resistor that is connected between the second external load and the second semiconductor switching element, and detects the second constant current; a step up circuit that steps up the power supply voltage by a predetermined voltage; a first drive circuit that is driven based on the stepped up power supply voltage, and controls the first semiconductor switching element based on the first constant current detected by the first shunt resistor; a second drive, circuit that is driven based on the stepped up power supply voltage, and controls the second semiconductor switching element based on the second constant current detected by the second shunt resistor; a first pad that is connected with the first semiconductor switching element; and a second pad that is connected with the second semiconductor switching element, wherein: the first semiconductor switching element and the second semiconductor switching element are arranged in a same chip and located adjacent to each other in the chip; the first and second pads are located between the first semiconductor switching element and the second semiconductor switching element; the first and second pads are electrically connected with the power supply terminal, which is a single terminal common to the first and second pads; and the first and second shunt resistors are located outward of a region containing the first and second semiconductor switching elements.