| 摘要 |
An infrared-emitting diode (IRED) is supplied with a current from a constant current source. This technique significantly reduces the power loss that occurs in a battery-powered remote control device, for example, as the battery voltage varies from a fully-charged level to a level at which the battery must be recharged. Because a certain level of current is required to operated the IRED, in this situation the circuit must be fabricated such that the required current is supplied when the battery needs charging. When the battery is operating at a higher level, power is wasted exponentially as excess current is supplied through the IRED. Supplying the IRED with a constant current source greatly reduces the power loss. The constant current source can take a wide variety of forms from a relatively simple MOSFET operating in saturation to more complex arrangement containing, for example, current mirrors, additional current sources, pass transistor logic, and digital-to-analog converters. The constant current source can also be fabricated with bipolar transistors and biCMOS technology <IMAGE> |
