ISL6551_06 Datasheet, PDF (19/26 Pages) Intersil Corporation – ZVS Full Bridge PWM Controller

ISL6551
Feedback
VOPOUT
EAO
EAI
FIGURE 16A. SECONDARY CONTROL
VOPOUT
VREF = 5V
IL207
Rectifiers
SYNCHRONOUS FETs
S+
SCHOTTKY
S+
SYNP
SYNN
S–
S–
FIGURE 17A. CURRENT DOUBLER RECTIFIERS
SYNCHRONOUS FETs
S+
SCHOTTKY
S+
SYNN
SYNP
TL431
EAO
EAI
S–
S–
FIGURE 17B. CONVENTIONAL RECTIFIERS
FIGURE 16B. 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.
S+
S–
FIGURE 17C. SELF-DRIVEN RECTIFIERS
Current Doubler Rectifiers -
1. Synchronous FETs are used for low output voltage, high
output current and/or high efficiency applications.
2. 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 -
1. Synchronous FETs are used for low output voltage, high
output current and/or high efficiency applications.
2. 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 18A-D.
19
FN9066.5
January 3, 2006