[Introduction]In many applications, it is important that the supply voltage is continuously available regardless of the circumstances. Ensuring this is sometimes not easy. A new concept could provide an optimized solution for designing extremely compact uninterruptible power supplies.
How can it be easier to obtain continuous, reliable power in power-critical applications?
In many applications, it is important that the supply voltage is continuously available regardless of the conditions. Ensuring this is sometimes not easy. A new concept could provide an optimized solution for designing extremely compact uninterruptible power supplies.
There are a variety of applications that require uninterruptible power supplies. An example is a RAID system for redundant data storage, which must be protected so that data is not lost in the event of a power failure at inconvenient times, such as during data backup activities. Systems with real-time clocks must also be powered continuously. This can come from batteries or other backup solutions. Other applications include telemetry applications in the automotive industry and drug delivery systems – such as controlled insulin pumps used in the healthcare industry.
Figure 1. Typical Application of Uninterruptible Power Supply
Figure 1 shows a typical industrial application of an UPS. Here it is for powering industrial sensors. The reliability of the system mainly depends on the power supply of the sensor. When system voltage is available, a linear charge regulator IC is used to charge the supercapacitor. If the system voltage drops, a boost regulator is used to boost the energy from the energy storage system to the desired supply voltage level. This system works well, but is difficult to implement because it requires many different energy converters. Furthermore, in many applications it must be ensured that no energy flows from the energy storage system back to the source (as shown in Figure 1). As shown in Figure 1, the supercapacitor should only power the sensor circuit and not any other electronics that might be connected to the 24 V line (shown on the left side of Figure 1). Energy storage systems are usually designed to power local loads rather than powering the entire system connected to the 24 V supply voltage. This requires diode D in Figure 1.
Figure 2. The Continua backup power concept integrating numerous system functions
Figure 2 shows a new concept supported by Analog Devices’ MAX38889. This is a highly integrated backup power solution called Continua™ for power rails up to 5 V, requiring only one IC and a few external passive components. The MAX38889 integrates a half-bridge that alternates between high-efficiency buck and boost modes.
Figure 3. Using ADI’s MAX38889 to implement a tiny Continua backup power solution
Figure 3 shows a complete working circuit. The logic switches and power switches are all integrated, so only a small external chip-level Inductor and a few backup capacitors are required in addition to the supercap.
The integrated high-side power switches are implemented using Analog Devices’ True Shutdown™ technology. Therefore, the system voltage can be separated from the capacitor voltage, and if the capacitor voltage is higher, no current will flow from the capacitor to the system.
While there are plenty of backup power solutions on the market for a wide range of voltages and currents, the MAX38889 Continua is a unique backup power solution with a compact design that can be easily added to a 5 V or 3.3 V supply line, requiring The development and implementation effort is very small. The solution also features a high conversion efficiency of up to 94% in charge and discharge mode, minimizing the size and cost of the energy storage system.
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