ISL6551_15 Datasheet, PDF (18/27 Pages) Intersil Corporation – ZVS Full Bridge PWM Controller

ISL6551
Figure 16 shows the block diagram of a power supply system
employing the ISL6551 full bridge controller. The ISL6551 not
only is a full bridge PWM controller but also can be used as a
push-pull PWM controller. Users can design a power supply by
selecting appropriate blocks in the “System Blocks Chart” based
on the power system requirements. Figures 17A, 18A, 19A, 20A,
21A, 22A, 23, 24A, 25, 26A and 28A have been used in the
200W telecom power supply reference design, which can be
found in the application note AN1002. To meet the specifications
of the power supply, minor modifications of each block are
required. To take full advantage of the integrated features of the
ISL6551, “secondary side control” is recommended.
V_IN
INPUT
FILTER
PRIMARY
FETs
CURRENT
SENSE
PRIMARY FET
DRIVERS
BIASES
MAIN
TRANSFORMER
ISL6551
CONTROLLER
SUPERVISOR
CIRCUITS
PRIMARY BIAS
SECONDARY BIAS
RECTIFIERS
SECONDARY
DRIVERS
FEEDBACK
OUTPUT
FILTER
V_OUT
FIGURE 16. BLOCK DIAGRAM OF A POWER SUPPLY SYSTEM USING ISL6551 CONTROLLER
System Blocks Chart
V_IN
V_INF
V_IN
L_IN
C_IN
V_INF
C_IN
FIGURE 17A. GENERAL
FIGURE 17B. EMI
FIGURE 17. INPUT FILTERS
General- Input capacitors are required to absorb the power
switch (FET) pulsating currents.
EMI- For good EMI performance, the ripple current that is
reflected back to the input line can be reduced by an input
L-C filter, which filters the differential-mode noises and
operates at two times the switching frequency, i.e., the clock
frequency (Fclock). In some cases, an additional
common-mode choke might be required to filter the common-
mode noises.
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FN9066.6
April 30, 2015