ISL6551_15 Datasheet, PDF (20/27 Pages) Intersil Corporation – ZVS Full Bridge PWM Controller

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VOPOUT
ISL6551
EAO
EAI
VOPOUT
V_REF = 5V
IL207
TL431
EAO
EAI
FIGURE 20A. SECONDARY CONTROL
FIGURE 20. FEEDBACK
FIGURE 20B. PRIMARY CONTROL
Secondary Control- In secondary side control systems, only a
few resistors and capacitors are required to complete the
feedback loop.
Primary Control- This feedback loop configuration for primary
side control systems requires an optocoupler for isolation. The
bandwidth is limited by the optocoupler.
Rectifiers
SYNCHRONOUS FETs
S+
SCHOTTKY
S+
SYNP
SYNN
S–
S–
FIGURE 21A. CURRENT DOUBLER RECTIFIERS
SYNCHRONOUS FETs
S+
SCHOTTKY
S+
SYNN
S–
SYNP
S–
FIGURE 21B. CONVENTIONAL RECTIFIERS
S+
S–
FIGURE 21C. SELF-DRIVEN RECTIFIERS
FIGURE 21. RECTIFIER
Current Doubler Rectifiers:
• Synchronous FETs are used for low output voltage, high
output current and/or high efficiency applications.
• Schottky diodes are used for lower current applications. Pins
S+ and S- are connected to the output filter and the main
transformer with current doubler configurations.
Conventional Rectifiers:
• Synchronous FETs are used for low output voltage, high
output current and/or high efficiency applications.
• Schottky diodes are used for lower current applications. Pins
S+ and S- are connected to the main transformer with
conventional configurations.
Self-driven Rectifiers- For low output voltage applications, both
FETs can be driven by the voltage across the secondary
winding. This can work with all kinds of main transformer
configurations as shown in Figures 22A through 22D.
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FN9066.6
April 30, 2015