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TECH | FOCUS High-Capacitance Supercapacitors Suit to Broader Application Fields New product: DMF series 1000mF 14 × 30 × 3.7mm Part No. Conventional product: DMF series 470mF 14 × 21 × 3.2mm Rated ESR Nominal Operating voltage (@1kHz) capacitance temperature range DMF4B5R5G105M3DTA0 5.5V 40mΩ 1,000mF -40°C - 70°C DMF3Z5R5H474M3DTA0 5.5V 45mΩ 470mF -40°C - 70°C Photo: DMF Series EDLC products Typical Supercapacitor Usage The low-ESR and high-capacitance DMF Series is used as an auxiliary power supply for assistance during peak output or backup. It can also be used in various devices, for example, it can reduce the load of a battery or serve as a maintenance-free power supply in combination with a power generation element. It can contribute to reducing the size of a power supply, and to the implementation of higher functionality and energy saving. Output Auxiliary power supply for peak output (Fig. 1) When the DMF Series is used as an auxiliary power supply during peak output, it is highly possible to reduce the size of power supply units, add a higher output function, and improve the performance. A sample application includes as peak-output auxiliary power supply for light-emitting diodes (LEDs), compact DC motor devices, gas and water smart meters, and Remote Keyless Entry (RKE) system. EDLC Load converter Battery Time Power supply EDLC Fig. 1: EDLC as auxiliary power supply for peak output Auxiliary power supply for backup (Fig. 2) The DMF Series makes it possible to achieve a high-output backup function in a confined space by taking full advantage of its features such as long life, as well as lower ESR and size smaller than a battery. In particular, it can be used as a memory backup for solid-state drives (SSD) and programmable logical controllers (PLC), and last gasp of communication devices. Power shutdown Output M urata Manufacturing Co., Ltd. has started mass production of the DMF Series supercapacitors, also called as electrical double-layer capacitors (EDLCs), that feature low equivalent series resistance (ESR) and high capacitance (1,000mF) from Oct. 2014. A supercapacitor is an electricity storage device that has higher capacitance than conventional capacitors such as ceramic capacitors and electrolytic capacitors, has lower ESR than batteries, and has long life. Among various supercapacitors, Murata’s DMF Series has the industry's lowest ESR level and can discharge electricity with a large output of several tens of watts. When Murata’s DMF Series is used as an auxiliary power supply for assistance during peak output or backup, the size of batteries and power supply units can be made smaller, energy loss can be reduced, and a high output function can be achieved. Murata has added a highcapacitance supercapacitor of 1,000mF to the DMF Series lineup besides the conventional 470mF supercapacitor products. This new DMF Series product enables peak output assistance and backup for even longer hours, and therefore there is high expectation for its use in various devices. This article introduces some applications that take maximum advantage of DMF Series supercapacitors. Power supply Power shutdown Load EDLC PS EDLC Time Fig. 2: EDLC as auxilliary power supply for backup AEI May 2015 33 TECH | FOCUS Battery load reduction (Fig. 3) The low-ESR and high-capacitance features of the DMF Series can be used to improve device functions and stabilize operations by leveling large fluctuations of a power voltage line. For example, it can be used as a power supply for audio equipment, various communication devices, portable printers, and security and health-care devices. Voltage Battery+EDLC Load Battery Battery only EDLC Time Fig. 3: Battery load reduction Energy storage device (Fig. 4) The DMF Series can serve as a maintenance-free power supply by making the most of supercapacitor’s long-life feature in combination with various power generation elements. The DMF Series can also minimize energy loss caused by an unstable input and high output by taking advantage of its lowESR feature. For example, it can be used a power supply for a sensor network system and the Internet of Things (IoT) device using energy harvesting. Fig. 5: Application example of EDLC for SSD backup CH1: Input signal CH3: Load current (use of current probe) Sound source (stereo output) R+ DC power supply (Stabilized power supply or Battery) Output EDLC Speaker Audio signal Power supply line Unstable input Class D amplifier stereo specifications R- L+ L- Load Harvester EDLC Time Inserting EDLC Fig. 4: Energy storage device Supercapacitor Sample Applications and Effects For SSDs When used as backup for enterprise SSDs (SAS, SATA, and PCIe) (Fig. 5), the DMF Series contributes to space saving by reducing the required number of tantalum capacitors and aluminum electrolytic capacitors. The energy that can be stored in a Murata supercapacitor 470mF product is 100 times or higher than high-capacitance tantalum capacitors. For example, when discharging is performed from 5.5 to 2.0V at 10W, supercapacitor can supply backup power for approximately 1sec. For battery-operated audio devices (Fig. 6) Supercapacitors are employed to sta34 Sine wave 1kHz, 1.0Vp-p &+&ODVV'DPSOLÀHUVSHDNHURXWSXW AEI May 2015 Polymer capacitor 220 F Approx. 700mAp-p EDLC 350mF Approx. 250mAp-p Fig. 6: Application example of EDLC for audio amplifier bilize the power supply of high-end portable audio devices (sound quality improvement). As a result, they contribute to sound quality improvement by stabilizing the power supply line. For gas, water smart meters (Fig. 7) When the DMF Series is used as an auxiliary power supply for communications and valve opening and closing, it contributes to extending the 15-year life of a primary battery to 20 years. The DMF Series can utilize the energy stored in a battery efficiently because it has low ESR and low loss in a low temperature environment. For LEDs (Fig. 8) Supercapacitors used in LED flash of digital still cameras and digital video cameras and LED beacon of fire alarms contribute to improving functions by enabling LED light emission through the high current. Regarding the supercapacitor application for flash, when LEDs are used for camera flash, they can provide longer life and the size of the circuit for flash function can be reduced. Such an application also can provide unique functions, for example, making it possible to change the light emission time and brightness more flexibly and perform continuous shooting function. Enables discharge for approximately 1sec with a potential difference from 5.5 to 2.5V when a DMF Series 1,000mF product is discharged at 4A. <After 15 years, 35ºC, 3.6V> 2W Constant Power Discharge by temperaure Power supply Output assist by EDLC Power management Load 3.8 P/N: DMF4B5R5G105M3DTA0 3.6 3.6V DMF series Voltage(V) Battery (Li-SOCl2, etc.) Balancing resistor 3.4 Communication function Metering function Power management 3.2 3.0 2.8 -30 2.6 25 2.4 M 2.2 Motor function 2.0 0.0 0.5 1.0 1.5 2.0 Time(sec) Other functions (display, etc.) Fig. 7: Application example of EDLC for smart meters Vout ( - 8V) or Vout ( - 5.5V) Vin Constant Current Discharge(@25ºC) (Charge Voltage: 5.5V) Vedlc ( - 5.5V) Lithium-ion rechargeable battery, etc. LEDs Murata’s EDLC series or AS3630 TPS6130* SCF04 Series connection AS3630 Parallel connection TPS6130* SCF04 Capacitor Voltage(V) LED FLASH Driver 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 1A 2A 4A 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 Time (sec.) Fig. 8: Application example of EDLC for LED flash Conclusion This article has introduced some applications and application examples of low-ESR and high-capacitance supercapacitors that make the most of their ad- vantages. Murata continues to work on developing even smaller products with lower ESR so that the devices can have higher functionality, smaller size, and energy-saving features. About This Article: The author, Atsushi Kawashima, is from the Planning and Sales Promotion Section, High Performance Power Device Dept. of Murata Manufacturing Co., Ltd. AEI May 2015 35