PFC Controller Integrates Functionality to Simplify Design
Sep 8, 2010 1:57 PM
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To meet ENERGY STAR regulations and reduce bill of material (BOM) cost, designers aim for stable performance with fewer components in their overall product design. This need for efficient devices is making Power Factor Correction (PFC) increasingly relevant to designers. Fairchild Semiconductor addresses this need with the FAN7930, an active PFC controller for boost PFC applications that operate in critical conduction mode (CRM). This device is ideal for LCD and PDP TV applications, as well as for applications using less than 200W where PFC is mandated, including Class C lighting equipment greater than 25W, and Class D PC, TV and monitors greater than 75W.
The FAN7930 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.
The FAN7930 also includes a maximum switching frequency limitation and stable operating at the abnormal condition such as high noise and current. The AC Absent Detection function increases system reliability during the fast AC On-Off Test or in the event of a short electric power failure.
Additionally, the device provides soft-start and overshoot-less functions, reducing voltage and current stress at start-up while eliminating audible noise from unwanted over-voltage protection (OVP) triggering.
Price: US$.1.00 in 1,000 quantity pieces.Availability: samples available now. Delivery: ARO 36 weeks.
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