ISL6551IREC Datasheet, PDF (18/23 Pages) Intersil Corporation – ZVS Full Bridge PWM Controller

ISL6551IREC
SYNCHRONOUS FETs
S+
SCHOTTKY
S+
SYNN
SYNP
S–
S–
FIGURE 17B. CONVENTIONAL RECTIFIERS
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, 18B, 18C and 18D.
Main Transformers
P+
S+
P–
S–
FIGURE 18A. FULL BRIDGE AND CURRENT DOUBLER
P+
S+
V_OUTF
P–
S–
FIGURE 18B. CONVENTIONAL FULL BRIDGE
P1–
S+
V_INF OR
CURRENT_SEN_P
P2–
S–
FIGURE 18C. PUSH-PULL AND CURRENT DOUBLER
P1–
S+
V_INF OR
CURRENT_SEN_P
V_OUTF
P2–
S–
FIGURE 18D. CONVENTIONAL PUSH-PULL
FULL BRIDGE AND CURRENT DOUBLER
No center tap is required. The secondary winding carries half
of the load, i.e., only half of the load is reflected to the
primary.
CONVENTIONAL FULL BRIDGE
Center tap is required on the secondary side, and no center
tap is required on the primary side. The secondary winding
carries all the load. i.e., all the load is reflected to the primary.
PUSH-PULL AND CURRENT DOUBLER
Center tap is required on the primary side, and no center tap
is required on the secondary side. The secondary winding
carries half of the load, i.e., only half of the load is reflected
to the primary.
CONVENTIONAL PUSH-PULL
Both primary and secondary sides require center taps. The
secondary winding carries all the load, i.e., all the load is
reflected to the primary.
Supervisor Circuits
INTEGRATED SOLUTION
• Intersil ISL6550 Supervisor and Monitor (SAM).
• Over-temperature protection (discrete)
• Input UV lockout (discrete)
VOPOUT
VREF5
BDAC
VCC ₁
VOPP ₂
VOPM ₃
VOPOUT ₄
VREF5 ₅
GND ₆
BDAC ₇
OVUVTH ₈
DACHI ₉
DACLO ₁₀
20 ^UVDLY
19 ^OVUVSEN
18 ^PGOOD _PGOOD
17 ^START START
16 ^PEN
PEN
15 ^VID0
14 ^VID1
13 ^VID2
12 ^VID3
11 ^VID4
FIGURE 19. ISL6550
18
FN6762.0
September 2, 2008