如何提高降压转换器的轻负载效率与LDO

如何提高降压转换器的轻负载效率与LDO

 

　　设计一个DC / DC转换器，只消耗微安培电流在无负载可以相比，以增加肌肉车与较轻的流体-你可能会得到它的工作，但它不会是容易的。在全负载电流的高效率在大多数现代DC / DC转换器是司空见惯的，但是，实现高效率时，负载被禁用或断开仍然是一个困难和/或昂贵的任务。

 

　　许多汽车和工业应用需要高效率的12 V或24 V降压电源转换从主电源下降到负载点（电压）在满负荷电压，但也需要非常低的电流消耗时，该设备是在空闲或关机状态。为了实现这样的低电流，您可以轻松地使用降压转换器（LDO）并联降压转换器，以实现最小的电流从电池中汲取时，系统进入轻负载/空载状态。

 

　　

 

　　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.

 

　　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.