電流源使線性穩(wěn)壓器提供更低的輸出電壓

　　傳統(tǒng)上，由于體系結(jié)構(gòu)對(duì)參考電壓的依賴性，線性穩(wěn)壓器的輸出電壓僅限于參考電壓。因此，由于舊一代架構(gòu)采用1.2 V作為參考，這些穩(wěn)壓器的最小輸出電壓限制在1.2 V，系統(tǒng)板上的集成電路需要更低的電壓來操作。因此，這些線性穩(wěn)壓器不能為需要小于1.2 V和更高電流的集成電路供電。

　　然而，一種新的線性穩(wěn)壓器結(jié)構(gòu)克服了這種低輸出電壓限制。通過取代傳統(tǒng)的電壓參考電流源，新一代線性穩(wěn)壓器可以提供輸出電壓遠(yuǎn)低于1 V，事實(shí)上，它有能力去低至零伏特，根據(jù)制造商。此外，這種新的線性穩(wěn)壓器架構(gòu)也可以配置為電流源。此外，不像舊一代線性穩(wěn)壓器，它可以并聯(lián)，以提供更高的輸出電流，如果需要的話。

　　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.