Conferences and Forums
Recaps of Recent Capacitor Developments
In July, Linear Technology Corp. introduced the LTC3226, an inductorless supercapacitor charger with backup PowerPath™ controller for Li-ion or other low-voltage system rails in applications that require short term backup power. The device employs a low-noise dual mode (1x/2x) charge-pump architecture with constant input current to charge two supercapacitors in series from a 2.5 to 5.5V input supply to a programmable capacitor charge voltage between 2.5 and 5.3V. Charge current is resistor-programmable up to 150mA. The device’s automatic cell balancing and voltage clamping features maintain equal voltages on both cells without requiring balancing resistors. This protects each supercapacitor from overvoltage damage that could otherwise be caused by mismatches in cell capacitance or leakage, while minimizing current drain on the capacitors.
The LTC3226 has two modes of operation: normal and backup. Operating mode is determined by a programmable power fail (PFI) comparator. In normal mode (PFI high), power flows from VIN to VOUT through a low loss external FET ideal diode, and the charge pump stays on to top off the supercapacitor stack. In backup mode (PFI low), the charge pump is turned off and the internal LDO is turned on to supply the VOUT load current from the stored supercapacitor charge while the external ideal diode prevents reverse current flow into VIN. Up to 2A of backup current may be provided from the supercapacitor through the internal LDO.
The LTC3226 operates with a very low 55µA quiescent current when the output voltage is in regulation. The basic charging circuit requires few external components and takes up little space; the IC is offered in a tiny 3 x 3mm QFN package. The device’s high 900kHz operating frequency reduces the size of external components. Internal current limit and thermal shutdown circuitry allow the device to survive a continuous short-circuit from the PROG, VOUT or CPO pins to ground. Other features include CAP PGOOD and VIN PFO (power fail) outputs as well as a VOUT RST output for system housekeeping.
In August, Ioxus, Inc. a manufacturer of ultracapacitor technology for transportation, alternative energy, medical, industrial and consumer product markets, announced the addition of WPG Americas to its North American distribution channel. WPG Americas serves industries such as semiconductors and passive, electro-mechanical and display products, significantly broadening Ioxus’ potential customer base in the region. By providing technical and marketing support to carefully selected channel partners, Ioxus can deliver components more quickly to more customers in more markets globally.
In October, Illinois Capacitor announced that its MHBS Series of metalized polypropylene film capacitors now includes an expanded range of capacitance values from 0.68 to 150µF and 10 different termination styles, including 2, 4 or 6 radial leads and various lug-type terminations. Voltage ratings up to 460ac and 1275WVDC are available.
ESR characteristics are described as excellent, varying from 7.1 to 22.5mΩ, depending on values. Operating temperature ranges from -40 to +100°C, providing extended life in high-performance applications. For highly reliability applications, the estimated life expectancy with rated voltage applied is 60,000 hrs. with Vac, or >200,000 hrs. at +70°C with WVDC applied. Very compact size, with high capacitance density provides, greater design options and PCB layout flexibility.
Later that month, Taiyo Yuden Co., Ltd. introduced the Polyacene Capacitors (Supercap) PAS2126FR2R5504, measuring 26 x 20mm with a maximum height of 0.9mm. At 0.9mm thin, the Polyacene Capacitor realizes a high capacitance of 0.5F. This product is well suited for pulse current discharge of LED flash, which enables clear photographic images at low light conditions, used in mobile phones, smartphones, digital still cameras and digital camcorders, where demand centers on more compact and thinner devices.
In addition, the Polyacene Capacitor can be used for pulse current discharge required by portable printers and scanners as well as SSD’s uninterruptible power supply applications.