Minimizing quiescent current (I_Q) is a key factor to reduce power consumption and manage battery life. An Internet-of-Things (IoT) sensor node is one of the best examples of why it’s important to minimize I_Q to extend battery life. For example, in the low-power IoT application shown in Figure 1, the SimpleLink™ MCU controls a door lock via Bluetooth®, a Wi-Fi® connection or both.

Because these types of systems spend the majority (>99%) of the time in standby mode, as shown in Figure 2, the I_Q in standby or sleep mode tends to be the limiting factor for battery life. Careful optimization of low-I_Q power-management blocks makes it possible to extend battery life from two years to more than five years.

Standby I_Q has long been a concern, but historically solutions were limited to a narrow set of low-power systems. Recent breakthroughs reduced the I_Q in power-management building blocks like DC/DC converters, power switches, low-dropout regulators (LDOs) and supervisors, widening the use of these blocks to end equipment such as industrial meter applications, automotive sensors and personal wearables.

Figure 1 Smart e-lock block diagram.

Figure 2 Current consumption vs. time in a smart e-lock.

Figure 3 5-V LDO I_Q over time.

As Figure 3 illustrates, the I_Q in 5-V LDOs has approximately reduced 90% every three years over the past 10 years. Both circuit improvements and optimized process technologies have enabled the reduction of solution area and improved transient-noise performance, while simultaneously reducing I_Q.