ISL6551 Datasheet, PDF (21/26 Pages) Intersil Corporation – ZVS Full Bridge PWM Controller

ISL6551
Output Filter
S+
L_OUT
VOUT
C_OUT
S–
FIGURE 20A. CURRENT DOUBLER FILTER
Secondary Drivers
MIC4421BM
SYNC2
/LOWER1
IN OUT
SYNP
GND
MIC4421BM
SYNC1
/LOWER2
IN OUT
GND
SYNN
FIGURE 22A. INVERTING DRIVERS
V_OUTF
L_OUT
F_CLOCK
V_OUT
C_OUT
FIGURE 20B. CONVENTIONAL FILTER
Current Doubler Filter - Two inductors are needed, but they
can be integrated and coupled into one core. Each inductor
carries half of the load operating at the switching frequency.
Conventional Filter - One inductor is needed. The inductor
carries all the load operating at two times the switching
frequency.
Controller
VSS ₁
CT ₂
RD 3
R_RESDLY 4
R_RA ₅
ISENSE ₆
PKILIM ₇
BGREF ₈
R_LEB ₉
CS_COMP ₁₀
OUTPUT
REFERENCE ^CSS 11
(BDAC)
EANI 12
EAI
EAO
EAI 13
EAO 14
ICL6551
SOIC
28 VDD
27 VDDP1
26 VDDP2
25 ^PGND
24 ^UPPER1
23 UPPER2
22 ^LOWER1
INPUT
UV & OV
21 LOWER2
20 SYNC1
19 SYNC2
18 ^{ON / OFF}
17 ^DCOK
LED
16 LSTSD
15 ^SHARE
LSTSD
SHARE
BUS
FIGURE 21. ISL6551 CONTROLLER
ISL6551 Controller - It can be used as a full bridge or push-
pull PWM controller. The QFN package requires less space
than the SOIC package.
MIC4422BM
SYNC1 IN OUT SYNP
GND
MIC4422BM
SYNC2 IN OUT SYNN
GND
FIGURE 22B. NON-INVERTING DRIVERS
T_SYN
SYN1
SYN2
F_SW
IN OUT SYNP
GND
IN OUT SYNN
GND
SYN1
SYN2
IC
INVERTING
SYNC2/LOWER1
SYNC1/LOWER2
MIC4421BM
NON INVERTING
SYNC1
SYNC2
MIC4422BM
FIGURE 22C. PRIMARY CONTROL
Inverting Drivers - Inverting the SYNC signals or the
LOWER signals with external high current drivers to drive
the synchronous FETs.
Non-inverting Drivers - Cascading SYNC signals with non-
inverting high current drivers to drive the synchronous FETs.
There is a dead time between SYNC1 and SYNC2. For a
higher efficiency, schottky diodes are normally in parallel
with the synchronous FETs to reduce the conduction losses
during the dead time in high output current applications.
Primary Control - This requires a pulse transformer,
operating at the switching frequency, for isolation. There are
three options to drive the synchronous FETs, as described in
previous lines.
21
FN9066.4
July 8, 2005