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International Rectifier Introduces Application-Specific Diodes for More Efficient Power Factor Correction
EL SEGUNDO, Calif. July 2003 - International Rectifier, IR® (NYSE: IRF), today introduces the ETX- and ETL-Series high efficiency diodes for active power factor correction (PFC) in switch mode power supply (SMPS) applications. Power factor correction circuits smooth out the pulsating AC mains current, allowing the maximum amount of power to be drawn from AC lines, and is used in a wide range of AC-operated electronic products, from large computer system servers and telecommunications systems to small notebook computer power adaptors, video games and other home entertainment devices. Power factor correction is legislated under IEC-6100-3-2 standards.
The new PFC-specific diodes enable lower system losses (less heat), and lower stress in switching components in power supplies, shrinking circuits and creating higher current density for space-restricted, high performance applications.
"IR's new ETX- and ETL-Series diode characteristics are fine tuned for maximum efficiency in the specific PFC applications. These new diodes are excellent complementary products for IR's K-Series HEXFET® power MOSFETs and WARP2™ IGBTs for PFC applications, creating a 'one stop source' for efficient PFC applications," said Stephen Oliver, Director, International Rectifier AC-to-DC Marketing.
Technical Highlights
The ETX-Series diodes have very low reverse recovery charge for continuous current mode (CCM) PFC, while the ETL-Series diodes have very low forward voltage drop for discontinuous current mode (DCM) PFC applications.
The CCM scheme is used in power supplies rated at 200W or higher, for high-end desktop PCs, system servers, telecommunications systems and large home appliances. In these high power applications, the reverse recovery of the PFC diodes can cause additional losses in the PFC circuit. In order to minimize overall system losses, the diodes used in CCM circuits must have very short reverse recovery time, which is also an indirect measure of reverse recovery charge. The IR ETX-Series diodes have low reverse recovery energy and a very short reverse recovery time of 15ns (8ETX06).
DCM PFC schemes are more common in power supplies in the 70W to 200W range. DCM power supplies are used in TV sets, computer monitors and similar electronic products. Since the current falls to zero during every switching cycle, these applications call for very low forward voltage drop to attain maximum efficiency. Compared to current industry-standard diodes for DCM PFC applications, the forward voltage drop is reduced by 50% in ETL diodes. The ETL diodes have the lowest forward voltage drop in the industry, at 0.81V at maximum junction temperature (8ETL06).
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