Fairchild Semiconductor (NYSE: F) has introduced the FAN7930, an active PFC controller product, to meet demand for boost PFC applications in Critical Conduction Mode (CRM). The device is suitable for LCD and PDPTV applications, as well as below 200W to force the use of PFC applications, including more than 25W Class C lighting equipment, as well as more than 75W Class D PCs, TVs and monitors.
The FAN7930 uses voltage mode PWM to obtain the MOSFET turn-off signal by comparing the voltage of the internal ramp signal with the output voltage of the error amplifier. Since the voltage mode CRMPFC controller does not require rectified AC line voltage information, the input voltage sense network required by the current mode CRMPFC controller can be omitted, thereby saving power.
The FAN7930 is available in an 8-pin SOP package with a PFC-ready pin to trigger the next power stage. Using the LLC conversion stage application as an example, a trigger operation occurs when the PFC output voltage reaches the proper level of hysteresis. Also in the next power stage, the PFC ready pin can eliminate an external circuit for PFC undervoltage lockout (UVLO) while reducing power consumption.
The FAN7930 also has a maximum switching frequency limit function that can operate stably under abnormal conditions such as high noise and high current. The AC loss detection function can improve the reliability of the system during the AC quick-switching test or in the case of a short-time power failure.
In addition, the new device provides soft-start and overshoot-less features that reduce voltage and current stress during startup and removes audible noise from overvoltage protection (OVP) triggering.
The FAN7930 uses voltage mode PWM to obtain the MOSFET turn-off signal by comparing the voltage of the internal ramp signal with the output voltage of the error amplifier. Since the voltage mode CRMPFC controller does not require rectified AC line voltage information, the input voltage sense network required by the current mode CRMPFC controller can be omitted, thereby saving power.
The FAN7930 is available in an 8-pin SOP package with a PFC-ready pin to trigger the next power stage. Using the LLC conversion stage application as an example, a trigger operation occurs when the PFC output voltage reaches the proper level of hysteresis. Also in the next power stage, the PFC ready pin can eliminate an external circuit for PFC undervoltage lockout (UVLO) while reducing power consumption.
The FAN7930 also has a maximum switching frequency limit function that can operate stably under abnormal conditions such as high noise and high current. The AC loss detection function can improve the reliability of the system during the AC quick-switching test or in the case of a short-time power failure.
In addition, the new device provides soft-start and overshoot-less features that reduce voltage and current stress during startup and removes audible noise from overvoltage protection (OVP) triggering.
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