FAN7688: Advanced Secondary Side LLC Resonant Converter Controller with Synchronous Rectifier Control

Datasheet: Advanced Secondary Side LLC Resonant Converter Controller with Synchronous Rectifier Control
Rev. 3 (961kB)
Product Overview
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The FAN7688 is an advanced Pulse Frequency Modulated (PFM) controller for LLC resonant converters with Synchronous Rectification (SR) that offers best in class efficiency for isolated DC/DC converters. It employs a current mode control technique based on a charge control, where the triangular waveform from the oscillator is combined with the integrated switch current information to determine the switching frequency. This provides a better control-to-output transfer function of the power stage simplifying the feedback loop design while allowing true input power limit capability. Closed-loop soft-start prevents saturation of the error amplifier and allows monotonic rising of the output voltage regardless of load condition. A dual edge tracking adaptive dead time control minimizes the body diode conduction time thus maximizing efficiency.
Features
 
  • Secondary Side PFM Controller for LLC Resonant Converter with Synchronous Rectifier Control
  • Charge Current Control for Better Transient Response and Easy Feedback Loop Design
  • Adaptive Synchronous Rectification Control with Dual Edge Tracking
  • Closed Loop Soft-Start for Monotonic Rising Output
  • Wide Operating Frequency (39 kHz ~ 690 kHz)
  • Green Functions to Improve Light-Load Efficiency - Symmetric PWM Control at Light-Load to Limit the Switching Frequency while Reducing Switching Losses - Disabling SR at Light-Load Condition
  • Protection Functions with Auto-Restart - Over-Current Protection (OCP) - Output Short Protection (OSP) - NON Zero-Voltage Switching Prevention (NZS) by Compensation Cutback (Frequency Shift) - Power Limit by Compensation Cutback (Frequency Shift) - Overload Protection (OLP) with Programmable Shutdown Delay Time - Over-Temperature Protection (OTP)
  • Programmable Dead Times for Primary Side Switches and Secondary Side Synchronous Rectifiers
  • VDD Under-Voltage Lockout (UVLO)
  • Wide Operating Temperature Range -40°C to +125°C
Applications
  • Desktop PC
  • Fully Configured Entry Level PC Server
  • Game Console
  • LED TV
  • PC Server
  • PDP TV
  • LCD TV
Evaluation/Development Tool Information
Product Status Compliance Short Description Action
FEBFAN7688-I00250A-GEVB
Pb-free
LLC Resonant, 250 W, 400 V to 12.5 V Converter, Evaluation Board
FEBFAN7688SJXA-CP14U306-GEVB
Pb-free
306 W/12 V PC Application with 12 VSB Module Evaluation Board
Availability & Samples
Specifications
Interactive Block Diagram
Product
Status
Compliance
Description
Package
MSL
Container
Budgetary Price/Unit
Type
Case Outline
Type
Temperature
Type
Qty.
FAN7688SJX Active
Pb-free
Halide free
FAN7688 SOP-16 565BF 1 260 Tape and Reel 2000 $0.821
Market Leadtime (weeks) : Contact Factory

Product
Description
Pricing ($/Unit)
Compliance
Status
Topology
Control Mode
fsw Typ (kHz)
Stand-by Mode
UVLO (V)
Short Circuit Protection
Latch
Soft Start
VCC Max (V)
Drive Cap. (mA)
Package Type
FAN7688SJX  
 $0.821 
Pb
H
 Active   
Half-Bridge
Current Mode
Up to 690
Yes
8.5
Yes
No
Yes
20
100 / 100
SOP-16
Case Outlines
565BF   
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