如何提高降壓轉換器的輕負載效率與LDO

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　　設計一個DC / DC轉換器，只消耗微安培電流在無負載可以相比，以增加肌肉車與較輕的流體-你可能會得到它的工作，但它不會是容易的。在全負載電流的高效率在大多數(shù)現(xiàn)代DC / DC轉換器是司空見慣的，但是，實現(xiàn)高效率時，負載被禁用或斷開仍然是一個困難和/或昂貴的任務。

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　　許多汽車和工業(yè)應用需要高效率的12 V或24 V降壓電源轉換從主電源下降到負載點（電壓）在滿負荷電壓，但也需要非常低的電流消耗時，該設備是在空閑或關機狀態(tài)。為了實現(xiàn)這樣的低電流，您可以輕松地使用降壓轉換器（LDO）并聯(lián)降壓轉換器，以實現(xiàn)最小的電流從電池中汲取時，系統(tǒng)進入輕負載/空載狀態(tài)。

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　　Ultimately， the ideal situation to prolong battery life in the system would be to disable every possible device from the input supply. In some cases though， a sub-regulated voltage is still necessary for certain components within the system to allow communication with other system blocks during the shutdown state （i.e. a CAN bus transceiver in an automotive application）。 DC/DC converters that are not specifically designed for light-load efficiency can consume several milliamps with no load. Additionally， converters that do exhibit high light-load efficiency will utilize frequency-foldback schemes and discontinuous mode operation， resulting in noisy output voltages and excessive EMI emissions. An LDO is ideal for light load situations because they can be designed to consume very low currents while maintaining a low noise output voltage. The no-load current into the input （also called “ground current”） can be on the order of a few micro amps or lower. Combining the performance of both converter and LDO， therefore， has obvious benefits.

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　　A simple method of using both in parallel is possible if the designer has the ability to disable the DC/DC converter when the loads will be minimal， i.e. using the same enable/disable signal for the converter that is used for the load. An example of this can be seen in Figure 1.

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