Minimizing quiescent current (IQ) is a mandatory requirement today to reduce power consumption and manage battery life, especially in low-power applications. This critical factor is particularly relevant for battery-powered devices, such as IoT sensor nodes. These systems spend most of their working time (99% or more) in standby or sleep mode, and IQ is often the limiting factor in extending battery life. Well-designed and optimized ultra-low IQ power management devices can extend battery life by years, enabling more functionality, longer life, and lower overall system cost.
I Q, also known as no-load quiescent current, represents the most important issue to overcome for always-on, low-power systems. However, standby IQ has long been an issue, as IQ reduction comes with trade-offs in transient noise performance, die package area, and output power range. This is why IQ reduction is considered a challenging task requiring careful re-examination of silicon technology and circuit technology. Optimizing IQ requires solving a series of competing design problems: while reducing IQ by orders of magnitude, designers must meet all important performance requirements in terms of transient response, noise, and accuracy.
Ultra Low-IQ Devices
Recent advances in electronic design and technology have lowered the IQ of most relevant power management building blocks, such as DC/DC converters, power switches, low-dropout regulators, and supervisors, making these devices widely available in critical equipment, Examples include industrial instrumentation applications, automotive sensors, and wearables. To achieve ultra-low IQ in power supplies, Texas Instruments (TI) has been investing in innovative time-saving and cost-effective solutions for decades.
“Our approach to helping engineers address low-IQ challenges in power supply designs is three-fold,” Cecelia Smith, vice president and general manager of TI’s boost and multichannel DC/DC, said in a news release. “First, we achieve low power and always-on through innovations in process technology optimized for ultra-low leakage through a very innovative control IP topology. Next, through innovative fast wake-up comparators and zero-IQ feedback control, We can achieve fast dynamic response times without compromising low power consumption. Finally, for the most space-constrained applications, we do all of this within a reduced form factor.”
TI recently launched three new industry low IQ products targeting industrial, automotive and any low IQ applications. The first product is the TPS61094, a bidirectional buck/boost converter. According to TI, it achieves a quiescent current as low as 60 nA and integrates supercapacitor charging, giving engineers the ability to support backup power applications such as smart meters (see Figure 1). Considering the high level of integration of the device, the size of the entire solution is very small.
With a low IQ of 60nA, the TPS61094 will help engineers extend battery life by up to 20 percent, according to TI. For example, a design engineer could use the converter to run a smart meter powered by a single battery for 10 years or more. In addition, this provides a very large savings in reducing operating costs, as the service does not have to travel to the field as often to replace batteries. In addition to low IQ, the TPS61094 achieves a very high efficiency of 96%. The TPS61094 can also support higher output currents in boost operation, enabling support for different radio standards such as NB-IoT, Bluetooth and newer wireless protocols.
“By integrating the buck charger and boost converter into a single IC with a bidirectional topology sharing an inductor and an input/output capacitor, component count can be reduced by up to 50%, freeing up board space and enabling compact design,” said Smith.
The second new low I Q product is the LMR43620, a 36V, 2A synchronous buck converter with industry best size and I Q for a very broad range of low power, wide input voltage industrial and automotive applications. The device is the industry’s first wide-V IN buck converter featuring less than 3µAI Q at 150˚CT J max.
“If I had to say one thing about this device, keeping the no-load operating current below 3 mA at 150˚C junction temperature is a major achievement for our team, so we are very proud of this device ,” said Troy Coleman, vice president and general manager of TI’s Power Switches, Interfaces and Lighting.
The LMR43620 is housed in a 2 × 2mm low electromagnetic interference (EMI) HotRod package, the smallest package in this class of buck converters. The package features wettable flanks and internal compensation for automotive designs, such as touch-sensitive infotainment systems (see Figure 2). Despite its very small size, it can still operate in very high ambient temperature environments with stable thermal performance.
The LMR43620 is pin-compatible with the LMR43610 (36 V, 1 A), LMR36506 (65 V, 600 mA), and LMR36503 (65 V, 300 mA), helping customers simplify the design of a variety of applications. All devices are available in industrial and automotive qualified versions.
In addition to the HotRod package, the LMR43620 supports several additional features for low EMI performance, including spread spectrum, pin selectability, forced PWM mode and frequency synchronization. Due to its ultra-low I Q, the device can achieve over 85% efficiency at 1 mA.
The third new product from TI is the Ideal Diode Controller family. Today, the amount of electronics (LED lighting, infotainment clusters, USB hubs, and always-on features like remote entry) entering cars is increasing dramatically. All of these new electronics require a protection system that is small enough, efficient, and fast enough.
“Our new LM74720 family of ideal diode controllers enables designers to achieve the lowest power consumption, fastest turn-on and turn-off times for reverse battery protection, and smallest solution size without impacting the desired system level protection for automotive applications,” Coleman said.