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  • Analysis of working principles of monolithic integrated voltage regulator

    作者:网站管理员来源:本站原创日期:2014-10-30 16:10:21点击:1481

    Monolithic integrated voltage regulator, which comprises a constant current source circuit, the drive voltage reference constant current source, a comparison amplifier constant current source and a comparison amplifier load constant current source. The constant current source circuit can not be conducted, at startup but to these constant current source note people base current to be switched on, to ensure that the circuit can work normally. Commonly used a circuit is started using FET, the other is a diode or transistor type isolation start.

    启动电路的作用是在刚接通直流输入电压时,使调整管、放大电路和基准电源等建立起各自的工作电流,而当稳压电路正常工作时启动电路被断开,以免影响稳压电路的性能。

    Effect of starting circuit is connected in just the input DC voltage, which makes the adjustment tube, amplifying circuit and a reference power supply of their working current, and when the voltage stabilizing circuit when in normal work start circuit is disconnected, so as not to affect the performance of the regulator circuit.

    在串联型稳压电源中,流过调整管的电流基本上等于输出的负载电流,当负载电流较大时,要求调整管有足够大的基极电流。为了减少推动调整管的控制电流,可采用复合调整管。

    In the stabilized power supply, current flows through the adjusting tube basically equal to the load current output, when the load current is larger, request to adjust the tubes are large enough to base current. In order to reduce the force to adjust the control current tube, can adopt the compound adjustment tube.

    基准电压的稳定性将直接影响稳压电源输出电压的稳定性和精度,因为基准电压的漂移会被放大而成为输出电压的温度漂移,所以一个良好的基准电压电路不仅要求它所提供的电压不随输人电压和输出电流而变化,同时还要求它的温度特性好。因此,在集成电路设计中,除了将基准电压部分的元件置于远离功率管的地方外,还将各元件尽量靠近,使它们接近等温区。在电路选择上,具有零温度系数的基准电压是确保集成稳压器的高精度等特性的必要条件。

    The stability of the reference voltage will directly affect the stability and accuracy of voltage regulator output voltage of power supply, because the reference voltage drift will be magnified and become the temperature drift of the output voltage, so a good reference voltage circuit not only requires the voltage provided by it does not change with input voltage and output current, also requires the temperature characteristics of it good. Therefore, in the integrated circuit design, in addition to the reference voltage portion of the element is positioned away from the power tube place outside, still will be as close as possible to each element, make them close to the isothermal region. In selecting circuit, reference voltage with zero temperature coefficient is the necessary condition to ensure the high precision characteristics of the integrated voltage regulator.

    比较放大器的作用是把取样电压与基准电压加以比较,并将误差信号放大,送到调整管的基极,推动调整管工作。为了提高稳压电路性能,比较放大器应具有较高的增益和温度稳定性。为了减少输出电压温度漂移,在单片集成稳压器中常采用差分放大器,同时采用恒流源做动态负载来提高放大器的增益。采用恒流源动态负载的优点是,除了能在不必使用辅助电源的情况下获得比采用欧姆电阻高得多的电压增益外,还能充分发挥集成电路的长处;同时,用输入电压做放大器电源时,恒流源在输入与输出之间还能起隔离作用。

    A comparison amplifier is the role of the sampling voltage and the reference voltage are compared, and the error signal amplification, to adjust the tube base, promote the adjustment of pipe work. In order to improve the voltage stabilizing circuit performance, a comparison amplifier should have high gain and temperature stability. In order to reduce the temperature drift of output voltage, in monolithic integrated voltage regulator is widely used in the differential amplifier, at the same time, the use of constant current source dynamic load to increase the gain of the amplifier. Using constant current source has the advantages of dynamic load is, in addition to get in without the use of auxiliary power than in the case of the voltage gain by ohmic resistance is much higher, can give full play to the advantages of integrated circuits; at the same time, input voltage amplifier power supply, constant current source between the input and the output can also play a role of isolation.