电流源使线性稳压器提供更低的输出电压

　　电流源使线性稳压器提供更低的输出电压

　　传统上，由于体系结构对参考电压的依赖性，线性稳压器的输出电压仅限于参考电压。因此，由于旧一代架构采用1.2 V作为参考，这些稳压器的最小输出电压限制在1.2 V，系统板上的集成电路需要更低的电压来操作。因此，这些线性稳压器不能为需要小于1.2 V和更高电流的集成电路供电。

　　然而，一种新的线性稳压器结构克服了这种低输出电压限制。通过取代传统的电压参考电流源，新一代线性稳压器可以提供输出电压远低于1 V，事实上，它有能力去低至零伏特，根据制造商。此外，这种新的线性稳压器架构也可以配置为电流源。此外，不像旧一代线性稳压器，它可以并联，以提供更高的输出电流，如果需要的话。

　　Adjustable regulator

　　Linear Technology’s LT3081 and LT3082 incorporate the new architecture to deliver new levels of performance with adjustable output voltage that can be programmed down to 0 V at high current. While LT3081 is rated for 1.5 A output current capability， the LT3082 is a 200 mA low-dropout linear regulator.

　　As shown in Figure 1， a precision 50 μA reference current source connects to the non-inverting input of a power operational amplifier. The power operational amplifier provides a low-impedance buffered output to the voltage on the non-inverting input. A single resistor from the non-inverting input to ground sets the output voltage. If this resistor is set to 0 Ω， zero output voltage results. Therefore， any output voltage can be obtained between zero and the maximum defined by the input， which in the case of LT3081， is 40 V maximum. The Table lists many common output voltages that can be generated using the closest standard 1% resistor values for RSET.