Issue link: https://resources.mouser.com/i/1442772
designers use to assess the available ICs. Traditional device priorities such as linearity, bandwidth, power dissipation, voltage offset, and bias current are still critical, but they have been joined by what was once a less-critical specification: Quiescent current. What is quiescent current (usually designated as IQ), and why is it increasingly important? In simplest terms, quiescent current is the current that the component still draws with no load. In recent years, quiescent current has come to the forefront as the need to minimize current (and thus power) use has become a major issue. First, there's the environmental aspects, often driven by regulatory mandates, although in actual terms the milliamps used by most of these components is truly insignificant in the bigger "green" picture. However, IoT systems often consist of self-powered modules that are not connected to an AC power line, but instead must operate using limited sources such as those from energy harvesting or a small battery, and that's where slashing quiescent current makes a big difference. This is especially the case as many IoT devices have very low operational duty cycles and are in sleep or idle mode a large percentage of the time. It's therefore wasteful of the limited energy resources to have components in active states when they are actually needed only for intermittent short bursts of data collection and connectivity. Low Quiescent Current: For IoT and Cars, Too How are today's ultralow quiescent current levels achieved? It's done via a combination of factors: Advanced process technicalities, innovative and clever IC topologies, and lower DC-rail supply voltages. Some op-amps and comparators also include a separate shutdown pin that the system processor controls and that forces the IC into an even lower quiescent current state rather than just relying on the inherent quiescent current level of an unloaded device. At the same time, these devices do not compromise on the other critical performance factors cited earlier. Ironically, it's not just IoT applications that are increasingly concerned about quiescent-current drain: Automotive applications are as well (Figure 2 and Figure 3). This seems incongruous compared to IoT applications, as the auto has a substantial battery typically rated at 100A-hr or more and is recharged when the car is running. But today's cars are loaded with electronic subsystems for the power train, for infotainment, and for safety/security under the advanced driver assistance systems (ADAS) designation. Figure 2: The automobile of today, and even more so of tomorrow, is a heavily sensored platform with unique requirements for low quiescent current despite the battery's capacity. (Source: Texas Instruments) Figure 3: Power train, ADAS, and infotainment subsystems all have signal-conditioning circuitry to extract useful information from the wide array of diverse sensors embedded in the vehicle. (Source: Texas Instruments) 12 TLV3691 0.9V to 6.5V Small Size Comparators • Wide Supply: 0.9V to 6.5V ±0.45V to ±3.25V • MicroPackages: DFN-6 (1mm × 1mm), 5-Pin SC70 • Input Common-Mode Range Extends 100mV Beyond Both Rails Learn more