Ultra low quiescent current power supply chip provides longer battery life
Time:2022-10-16
Views:1715
One of the most critical challenges in today‘s electronic design is to reduce energy consumption. Power management is an important design consideration for many devices, especially those that rely on battery operation. As a result, most systems use various power management operating modes.
Functions such as standby, sleep, power saving, hibernation, and shutdown are critical for designers to reduce power consumption and extend battery life. In each mode, the current in the sleep phase can easily change from a few mA to nA.
The emergence of wearable devices makes this task difficult, in part because of the need to use small batteries to ensure small factors. The trend to use smaller batteries to accommodate smaller, lighter and more powerful electronic devices has led to some compromises. The Internet of Things (IoT) and all connected devices increase this demand, requiring reliable operating modes over a long period of time and under various operating conditions. Battery powered systems require careful zoning, compact space utilization, and efficient use of available power.
The high efficiency of these devices is first shown in the necessary standby phase for a long time. In these cases, the energy consumption is defined by a quiescent current (IQ) different from the turn off current. It is the working state of the circuit when no load is controlled. Quiescent current is usually confused with quenching current, which is the current absorbed when the equipment is turned off, but the battery is still connected to the system.
Why ultra-low quiescent current?
Although the active current consumption is an important factor to extend the battery life, the service time of the battery itself also depends on other operating modes, especially the standby mode. The absorbed current (Iq) in the standby phase must allow the device to wake up at any time to execute requests from the microcontroller.
Iq is the main index of standby power consumption of electronic systems and an important design parameter of modern low-power DC/DC converters used in power management circuits. Iq can evaluate different factors, such as power consumption of small load.
Power management usually consists of voltage regulators, such as switching regulators that increase or decrease voltage or regulators with low dropout (LDO). Some involve more architectures, and may even involve chargers. Reducing I q will improve efficiency, so it will prolong battery life by consuming less battery power.
Power supply design
The power management circuit includes multiple DC/DC solutions for powering sub components of devices such as sensors and microcontrollers (MCU). Low power MCU will affect the energy efficiency of the whole system. MCU has different shapes, sizes and architectures, but for connected IoT devices, 32-bit ARM microcontroller is a good choice. These MCUs are well supported by many manufacturers and are relatively easy to develop powerful and portable software.
Manufacturing processes that produce electronic components also affect energy efficiency. For example, advanced CMOS technology helps ensure correct battery use while reducing consumption. Designers need to balance capacity and size through efficient power management technology. Improving the energy efficiency of the system is a common method to extend the battery life.
The power management part involves the use of voltage monitors to ensure that the entire power system works properly. If the voltage is interrupted, the monitoring solution must signal an error so that the rest of the system can shut down correctly. The fast start delay allows voltage faults to be detected before the rest of the system starts, providing maximum safety in hazardous conditions. Texas Instruments (TI) TPS3840 Nanopower high input voltage monitor with manual reset and programmable reset time delay provides this high-precision solution.
With the growth of mobile device product portfolio year by year, lithium-ion batteries need to be specially careful through special charging cycles to maximize battery life. The battery charging of wearable devices is challenging because the battery must be small in size and large in capacity.
TI also offers BQ25619, a new switch integrated battery charger (IC) that supports 20 mA termination current. It increases battery capacity by 7% and reduces battery leakage to 6% in transport mode. The device is designed for more efficient medical and personal electronic applications, such as hearing aids.
DC/DC solutions
Selecting the appropriate power management device for the application is associated with the architecture of the DC/DC solution. Factors that should be considered when selecting a DC/DC solution include quiescent current (the lower the value always represents the ideal choice) and efficiency (the higher the percentage, the longer the battery life). Ideally, the efficiency is>90% at the µ A level. Another parameter is the input voltage range that allows operation even when the battery is almost "dead".
Power management integrated circuit (PMIC) includes more than ten LDOs. LDOs are also integrated into microprocessors, graphics processing units (GPUs), and many other systems on a chip (SoC). The two major types of regulators are linear regulators (LDO) and switching regulators.
Because switching power supply has advantages in power density and overall efficiency, switching power supply will certainly be used in large quantities. However, compared with switching regulators, LDO is used because of its low output voltage noise, small size and low cost. There is usually a trade-off between achieving very low Iq and meeting other key parameters at the same time, such as excellent dynamic performance, low output noise, and high power noise rejection.
TI introduced an ultra-low power consumption, low dropout (LDO) linear regulator TPS7A02, which claims that the lowest Iq in the industry is less than 25 nA, which is one tenth of the competitive ultra small devices. The new controller enables engineers to at least double the battery life, and claims to have first-class transient response, which can speed up wake-up, improve application response time and dynamic performance.
In addition, small size allows designers to reduce the size of the final product, making it the best choice for all wearable applications.
TPS7A02 can reduce the size of the solution by 70%, enabling engineers to add more functions to their designs in space constrained applications, or reduce system costs by using smaller circuit boards.
TPS7A02 is used for low-power applications such as grid infrastructure, building automation, and medical devices (Figure 2). By using this device in the design of wireless visual doorbells and security cameras, engineers can achieve a battery life of 24 months or more (up to four times the industry standard).
"As consumers want to reduce the frequency of charging or replacing batteries, there is an increasing demand for electronic products that can extend battery life, be more efficient, and be smaller. Low quiescent current plays a key role in helping engineers meet all these challenges," said Mike Beckman, vice president of Texas Instruments (TI). "That‘s why TI continues to focus on developing and providing innovative low Iq DC/DC converters, LDOs, battery management systems and other power components to help engineers solve industrial and personal electronics challenges around small, low-power, long-life designs."
TI also provides TPS62840, which is an ultra-low power switching regulator with a working IQ of 60 nA. The wide input voltage (V IN) range of 1.8 V to 6.5 V supports various battery chemical compositions and configurations. It can be used in many battery powered, always on industrial and personal electronic applications, including narrowband Internet of Things, grid infrastructure devices, and wearables.
Both ICs operate at very low quiescent current, providing a simple solution that helps improve the battery life of any battery powered device. A significant reduction in quiescent current can cause applications to run for seconds, minutes, hours, or even days.
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