Power Integrations (San Jose, CA) announced the availability of the Qspeed family of advanced diodes. Qspeed diodes use a unique silicon-based process to combine an extremely low reverse recovery charge (QRR) with a very soft recovery waveform. Together, these features help designers optimize the efficiency and EMI performance of their power conversion circuits.
Qspeed diodes are ideal for continuous conduction mode (CCM) boost power factor correction (PFC) circuits, and as output diodes for hard-switching applications. In PFC circuits, Qspeed diodes can provide an overall switching performance that is comparable to silicon-carbide (SiC) diodes at much lower cost. When a silicon PN diode is reverse biased and turns off, the current rapidly falls to zero and then briefly flows backwards through the diode as the PN junction switches from conduction to blocking mode of operation.
The product of time and negative current (i.e., the area under a plot of instantaneous current vs. time during commutation) is defined as reverse recovery charge, or QRR. The QRR flows to ground through other devices in the system and the energy is wasted as heat, reducing efficiency and possibly raising the temperature of costly associated components, such as MOSFETs. Qspeed diodes have the lowest QRR of any low-cost, silicon-based diode. They supplant ultrafast silicon diodes in PFC and rectifier applications targeting increased efficiency or temperature reduction, and they replace silicon-carbide diodes in applications with aggressive cost goals.