Source : Mouser Electronics
Perhaps a few of you readers have seen the new Marvel superhero movie: Ant-Man and the Wasp (2018). In it, Dr. Henry “Hank” Pym, played by Michael Douglas (1944–), discovered the power to shrink the size of just about anything you can imagine. The scene where he shrank his building and rolled it away like a travel suitcase was especially cool. While his ability to use size-changing technology creates a fun action movie, in the real world, this capability is also finding its way into the latest technological advancements in analog power design—minus the ability to open a tunnel to the quantum realm, of course.
The Internet of Things (IoT) has been called the Smart Revolution. This revolution is characterized by a sudden, radical, and complete technological change that revolves around the connection of sensors and machines. It is called a “revolution” because it generates a tremendous impact on how society manages its production, distribution, and consumption of goods and services.
Today’s proliferation of mobile devices in the form of smartphones and personal wearables allows for autonomous operation of wireless communications to transfer digitally encoded information via radio frequency (RF) wireless technology. Typically, the ideal in IoT is to minimize a sensing device’s power consumption in both its active and sleep states. Minimizing power consumption allows for long-term employment of batteries without requiring constant recharging, change, or disposal. Together with this is the desire for smaller packaging volumes. However, small packages limit the available coulometric capacity of a battery, measured in milliampere hours (mAh).
Commonly employed IoT design specifications often seek 10-year shelf and service lifetimes. To hit these targets, leading-edge power supply technology company ROHM Semiconductor has focused its research and development (R&D) resources on reducing integrated circuit (IC) power consumption. At the start of ROHM’s development efforts, the lowest baseline current consumption in the industry for power supply ICs was 360nA. Utilizing their analog expertise, ROHM Semiconductor was able to develop a new product line, the Nano Series, to achieve more compact parts that require less energy to operate.
A Two-Pronged Approach: Nano Pulse ControlTM
A method to make smaller analog power parts is to reduce the switching ON time along with the size of the inductor coil. ROHM went to work on developing ultra-high-speed control technologies that reduce switching ON time to less than 1/10 (at 9ns) of their conventional products (120ns). They named this ultra-high-speed control technology Nano Pulse ControlTM.
In addition to faster switching ON speeds for the analog power block, enabling stable control of the narrowest pulse widths as possible provides a monolithic power-supply solution for applications demanding large step-down ratios, such as in mild hybrid electric vehicles (HEV) where voltage conversion from 48VDC to 3.3VDC (14.5:1) is required.
ROHM Semiconductor’s BD9V10xMUF Buck Converters with Nano Pulse ControlTM are ideally suited for this role and can directly replace the current two-step, step-down buck converters, reducing space requirements while simplifying power supply system design. These 1-channel, 1A (max output), wide output voltage range (0.8VDC–5.5VDC), 1.9MHz–2.3MHz, synchronous buck converters with Nano Pulse ControlTM provide solutions for greater miniaturization and avoidance of AM radio interference in automotive subsystems. With a wide input voltage range (16VDC–60VDC) and very short minimum pulse widths, they can directly step down from 60VDC→2.5VDC (24:1) at 2MHz. Beyond HEVs, Nano Pulse ControlTM provides value in applications ranging from industrial robots to base station sub-power supplies (Figure 1).
Figure 1: Nano Pulse ControlTM is ideal for a wide variety of applications. (Source: ROHM Semiconductor)
Nano EnergyTM
There is a more direct approach than Nano Pulse ControlTM, however, which involves designing analog power products for stable operation utilizing ICs that consume very low currents. Low current consumption parts directly lead to more success among applications and devices that demand long-term operation on battery power. These parts are also suitable for use in extremely low-power environments, such as energy harvesting systems that generate small amounts of electricity from light, heat, and vibration. Applications that can benefit from this technology include smoke detectors, thermostats, portable devices, wearable devices, low Iq applications without a standby switcher, and energy harvesting devices.
Nano EnergyTM is a breakthrough technology developed by ROHM Semiconductor that decreases current consumption during ultra-light loads while minimizing the ensuing trade-off. It integrates bipolar junction transistor (BJT) as well as complementary metal-oxide semiconductor (CMOS) and double-diffused metal-oxide semiconductor (DMOS) transistor technologies into a unique 0.35µ BiCDMOS power process. The result is a quiescent current consumption of just 180nA, the lowest in the industry (Figure 2).
Figure 2: A broad range of applications can benefit from Nano Energy. (Source: ROHM Semiconductor)
Nano EnergyTM technology built into the BD70522GUL Ultra-Low Iq DC/DC Buck Converter delivers twice the amount of the battery drive time of conventional products in a no-load (i.e., standby) state. A seamless switching mode control (SSMC) function is built in that smoothly and automatically switches the load mode based on the load current, providing a higher than 90 percent power conversion efficiency. With Nano EnergyTM technology, high conversion efficiency occurs over the widest current range in the industry: 10µA–500mA, while consuming less than 1µA. It offers constant-on time (COT) control along with an ultra-low-power (ULP) mode to provide a superior transient response. Selection of the output voltage is enabled from among nine preset voltages using VSEL pins. When the input voltage gets close to the output voltage, the IC enters 100 percent ON mode, where switching operation stops.
Conclusion
The Smart Revolution requires cutting-edge analog power solutions. It would be great to have Dr. Pym’s power to easily shrink both physical size as well as electrical power consumption. Until then, however, ROHM Semiconductor offers its trademarked and proprietary Nano Series featuring a two-pronged approach—Nano Pulse ControlTM and Nano EnergyTM—that delivers only the most essential power. ROHM Semiconductor’s Nano Series provides industry-leading step-down ratios with ultra-low current consumption to satisfy even the most demanding applications. This will help make you, the engineering designer, a superhero.
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