onsemi MC33364DR2G

The MC33364 series represents a variable--frequency current--mode critical--conduction solution with integrated high voltage startup and protection circuitry to implement an off--line flyback converter for modern consumer electronic power supplies. Different frequency clamp options offer different customized needs. This device series includes an integrated 700 V Very High--Voltage (VHV) start--up circuit. Thus, it is possible to design an application with universal input voltage from 85 Vac to 265 Vac without any additional startup circuits or components. The critical conduction feature offers some advantages. First, the MOSFET turns on at zero current and the diode turns off at zero current. The zero current reduces these turn--on and turn--off switching losses. It also reduces the Electro--Magnetic Interface (EMI) of the SMPS and a less expensive rectifier can be used. Second, by preventing the SMPS from entering the discontinuous conduction mode (DCM), the peak MOSFET drain current is limited to only twice the average input current. It needs a smaller and less expensive MOSFET. Third, by preventing the SMPS from entering the Continuous Conduction Mode (CCM), the flyback topology transfer function stays first--order and its feedback compensation network is considerably simplified. It also maximizes the power transfer by the flyback transformer to its 1/2 LI² limits.

• Lossless Off--Line Startup
• Leading Edge Blanking for Noise Immunity
• Watchdog Timer to Initiate Switching Operating Temperature Range -25°C to +125°C
• Shutdown Capability
• Over Temperature Protection
• Optional/Adjustable Frequency Clamp to Limit EMI
• This is a Pb--Free and Halide--Free Device