5000 µF capacitor can be embedded in a smartcard

November 18, 2015 // By Graham Prophet
An electric double-layer capacitor from TDK presents 5 mF capacitance in a package with a maximum thickness of 0.45 mm, enabling it to be used as the power source for small e-paper displays and advanced biometric authentication systems

EDLC041720-050-2F-13 is an ultra-thin, high-energy capacitor electric double-layer capacitor with a footprint of 27 x 17 mm that can be mounted inside a smart card or other thin device. When fully charged, it provides around 50 mJ of energy to power a load. In smart cards, its fast-charging characteristics make it compatible with radio-frequency energy harvesting circuits. Tests based on NFC energy-harvesting circuits in use today show that its 5 mF capacitance can be charged in less than 1 sec by the field emitted by a standard NFC reader.

When embedded in a contactless ticketing card for users of a metro transit system, for instance, the EDLC041720-050-2F-13 is fully charged in the time it takes the user to present the card to the entry gate’s card reader. The energy stored on the card on entry to the transit system is sufficient to refresh the card’s e-paper display, enabling the card to show, for instance, an updated read-out of the user’s remaining credit.

The device’s 5 mF capacitance also provides sufficient energy to power advanced biometric forms of authentication, as used for example in contactless access control cards. While RF energy harvesting is suitable for many smart and contactless payment card applications, the capacitor may also be charged by other forms of harvested energy, such as that generated by TDK film solar cells.

Despite being only about one fifth as thick as TDK’s previous generation of EDLCs, the EDLC041720-050-2F-13 is resistant to damage by twisting and bending, and offers a long operating lifetime. It can reliably be used in smart cards that must conform to the ISO 10373-1 5.8 international standards for dynamic bending stress, and ISO 10373-1 5.9 for dynamic torsion stress. It is rated for operation over a temperature range of -20C to 60C. It also has high resistance to electro-static discharges and pressure. The EDLC041720-050-2F-13 contains no rare or heavy metals, is non-flammable, and poses no risk of