An extremely important challenge facing Electronic application designers today is to minimize the energy consumption of electronic systems. To achieve this goal, most systems utilize different low-power modes to help reduce overall power consumption. When using different operating modes, the system power supply current varies greatly. The lower one is only a few microamperes (μA) or less than 1 microampere in sleep mode, and the higher one is tens of milliamps (mA) or even hundreds of milliamps in full power mode. Milliampere. Low-dropout linear regulator (usually referred to as LDO) is a common building block of any power system, and the choice of linear regulator has an important impact on the overall energy consumption of the system. Not only that, system design often requires LDOs not only to have ultra-low quiescent current characteristics, but also to provide good dynamic performance to ensure a stable and noise-free voltage input, suitable for sensitive circuit applications. These requirements are often mutually exclusive, posing real challenges for IC designers. Therefore, there are few LDOs on the market that meet both requirements.
This article will discuss the need to provide low I when choosing LDOQA compromise between good dynamic performance and some current techniques that can achieve an acceptable balance.
Choose LDOFactors to be considered
When selecting linear regulators for low-power applications, engineers mainly search for ultra-low I that meet their input voltage and output current specificationsQ(The definition of this article is the quiescent current IQ<15 μa) ldo. when according to iQSpecifications can provide some good initial information related to the current consumption of the LDO, but IQTwo LDOs that are the same or similar may differ greatly in dynamic performance. If we think back IQIs defined as the ground current consumption under no load conditions, then IQIt becomes an actual parameter. In actual cases, it may be more appropriate to view the ground current consumption under very light load conditions (a few microamps to hundreds of microamps). It should be noted that after evaluating various LDO products of different manufacturers, it is not difficult to find the I in the data sheetQThe specifications are only for perfect no-load conditions, rather than realistic output loads of 10 to 100μA. In some cases, knowing the ground current characteristics related to input voltage or temperature is also meaningful. Some voltage stabilizers on the market obviously increase the ground current when the input voltage drops, and the LDO enters its voltage drop zone. This can be an important factor when choosing an LDO for battery-powered equipment. Other unexpected current consumption may have a responsible impact on the product, greatly reducing battery life. If the application is idle or dormant most of the time and consumes only a small amount of current, this unexpected impact is particularly serious. Designers should always read I of the data sheetQSpecifications, and if possible, before deciding to choose a particular LDO, review the relevant IQWith ILOADComparison chart.
Ultra low IQ LDODynamic performance parameters