PFC Controller Integrates Ready Pin
Thu, 07/01/2010 - 1:17pm
Fairchild Semiconductor announced its FAN7930 active PFC controller for boost PFC applications that operate in critical conduction mode (CRM). This device is appropriate for LCD and PDP TV applications, as well as for applications using less than 200 W where PFC is mandated, including Class C lighting equipment greater than 25 W, and Class D PC, TV and monitors greater than 75 W. The IC uses a voltage-mode PWM which compares an internal ramp signal to the error amplifier output, resulting in a MOSFET turn-off signal. Because the voltage-mode CRM PFC controller does not need rectified AC line voltage information, it saves the power loss of an input voltage sensing network necessary for a current-mode CRM PFC controller. Packaged in an 8-pin SOP, the FAN7930 includes a PFC-ready pin which can be used to trigger the next power stages, as an example in the LLC conversion stage, when PFC output voltage reaches the proper level with hysteresis. Also in the next power stage, the PFC-ready pin eliminates the need for an external circuit for PFC under-voltage lockout (UVLO) while reducing power loss.