EDNE July 2012 - (Page 8)

pulse INNOVATIONS & INNOVATORS 1200V, direct drive, silicon carbide JFETs nfineon Technologies’ CoolSiC 1200V SiC JFET family will resolve, the company asserts, the reliability issues that have characterised some attempts to build efficient high-voltage switches in SiC (silicon carbide). They also offer fast switching and efficient use of substrate area, which will enable Infineon to control manufacturing costs. Infineon is aiming the parts, in the first instance, at the photo-voltaic (solar) inverter market segment as well as UPSs and industrial motor drives; these SiC JFETs have lower switching losses compared to IGBTs, which allow higher switching frequencies to be used without sacrificing overall system efficiency. This enables the use of much smaller passive components. Alternatively, a higher output power solution can be built within the same I inverter housing. As well as reduced switching losses compared to IGBTs, lower conduction losses will also be possible, especially at low and partial load factors. The JFET is inherently a normally-on switch; Infineon has addressed the issue of easeof-use with its Direct Drive Technology, yielding a part that operates normally-off. This assembles a cascode configuration with a separate low-voltage p-channel FET, and adds a control/driver IC. The result is a device that ensures safe system startup conditions as well as fast and controlled switching: the sequence is that the driver IC looks at the operating conditions at power-up and only if all parameters are within limits, turns on the protection FET which drives the JFET. The CoolSiC JFET has a monolithically integrated body diode www.infineon.com/coolsic that has a switching performance comparable to an external SiC Schottky barrier diode, Infineon adds. Switching losses also become temperature independent – there is no reverse recovery charge, and output characteristics are ohmic. The intial product specification shows a range of switches in TO-247 outlines, with RDS(on) values of 35-100 mΩ. Samples are promised by the time this report appears, with production volumes scheduled for 2013. Example pricing for the IJW120R100T1 (100 mΩ) will be €18.44 each (1000). Infineon has stated that the next development step will be to combine the SiC switch and low-voltage FET into the same package. —by Graham Prophet Infineon Technologies, User-programmable current transducers EM has updated its range of current transducers for powercontrol circuits with the HO series, that offers increased accuracy and user-programmabilty. They are open-loop Hall-effect devices that measure up to 25A DC, AC or pulsed; are digitally programmable for parameters including gain, response time, and voltage reference level; have user-selectable over-current detection, fault reporting and low-power mode; and come L LEM offers accuracy close to that of a closed-loop transducer in it open-loop, HO-series parts. pre-calibrated for three nominal current ranges. The HO series measure up to 8, 15 or 25 ARMS, with a response time of 2 to 6 μsec. Both of these parameters, and several others, are userprogrammable by a simple serial digital bit-sequence, generated by the system’s host microcontroller. Output is a scaled analogue voltage; in most systems this will be converted to a digital value by an analogue/digital converter (ADC) which requires a reference voltage. The designer can program the LEM HO-series transducer to output a reference of 0.5, 1.5, 1.65 or 2.5V on a dedicated pin. The transducers operate from a single supply voltage at 3.3 or 5V, occupy a PCB-mountable, small (12 mm wide x 23 mm long x 12 mm high), lightweight (5g) package which incorporates three separate primary conductors. A single magnetic core surrounds all three conductors, and you can change the response by connecting the three paths in series or parallel. Versions will be available for both through-hole and surface-mount assembly. —by Graham Prophet LEM, www.lem.com 8 EDN EUROPE | JULY 2012 www.edn-europe.com http://www.infineon.com/coolsic http://www.lem.com http://www.edn-europe.com

Table of Contents for the Digital Edition of EDNE July 2012

Cover
Contents
International Rectifer
Microchip
FTDI
Masthead
Comment
International Rectifer
Pulse
Analog Devices
Digi-Key
Analog Devices
Test & Measurement
Agilent Technologies
Baker's Best
Messe München
Understand and characterize envelope-tracking power amplifiers
Digi-Key
Cover Story
Coilcraft
Digi-Key
Signal Integrity
Altera
USB 3.0 : Bringing SuperSpeed connectivity to mobile devices
Digi-Key
Developing high-frequency integrated circuits for test and measurement
Design idea
Product Roundup
Tales from the cube

EDNE July 2012