© 2015 Fairchild Semiconductor Corporation
3
FEBFAN7688SJXA_CP14U306
• Rev. 1.1
This user guide supports the 306 W evaluation board for the 80Plus Platinum solution
based on a Continuous Conduction Mode (CCM) PFC and LLC convertor using the
FAN6982 with the FAN7688. It should be used in conjunction with the FAN7688
datasheet as well as Fairchild’s application notes and technical support team. Please visit
Fairchild’s website at
1.
Introduction
The LLC converter in this Evaluation Board (EVB) is controlled by the FAN7688; it’s a
16-pin controller and locates in secondary side. The FAN7688 includes PFM and PWM
controls to optimization efficiency for all loading, its combine advantage SR control
improves efficiency. It employs a current mode control technique based on charge
control; this provides a better control-to-output and line-to-output transfer function of the
power stage, simplifying the feedback loop design while allowing true input power limit
capability. The PFC is controlled by the FAN6982, based on Continuous Conduction
Mode (CCM), which employs leading edge modulation for average current control and
has a number of advanced features for better performance and reliability.
1.1.
Features
LLC
:
Secondary Side PFM Controller with Synchronous Rectifier Control
Charge Current Control for better Transient Response and Simplified Feedback Loop
Design
Adaptive Synchronous Rectification Control with Dual Edge Tracking
Closed Loop Soft-Start
Green Functions to Improve Light Load Efficiency
-
Symmetric PWM Control at Light Load to Limit the Switching Frequency while
Reducing Switching Losses
-
Disabling SR During Light Load Operation
Complete Protection Functions with Auto-Restart
PFC
:
Continuous Conduction Mode and Average-Current-Mode Control
Power-On Sequence Control
Brownout Protection
Fulfills Class-D Requirements of IEC 61000-3-2
Universal AC Input Voltage
Efficiency Optimization by External Output Voltage Adjustable Circuit
