ISL6551IREC Datasheet, PDF (20/23 Pages) Intersil Corporation – ZVS Full Bridge PWM Controller

ISL6551IREC
SYN1
SYN2
IC
INVERTING
SYNC2/LOWER1
SYNC1/LOWER2
MIC4421BM
NON INVERTING
SYNC1
SYNC2
MIC4422BM
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.
Q3_G
LOWER1
LOWER2
Q3_S
Q4_S
Primary FET Drivers
PUSH-PULL DRIVERS
Push-Pull Medium Current Drivers
Upper drivers are not used. No external drivers are required.
Secondary control. Operate at the switching frequency.
Push-Pull High Current Drivers
Upper drivers are not used. External high current drivers are
required and less power is dissipated in the ISL6551IREC
controller. Secondary control. Operate at the switching
frequency.
Push-Pull Primary Control
Upper drivers are not used. Both lower drivers can directly
drive the power switches. External drivers are required in
high gate capacitance applications.
LOWER1
LOWER2
HIP2100IB
HI HO ^Q3_G
LI HS
VSS LO
Q3_S
Q4_G
Q4_S
Q4_G
FIGURE 23A. PUSH-PULL MEDIUM CURRENT DRIVERS
FIGURE 23B. PUSH-PULL HIGH CURRENT DRIVERS
LOWER1
LOWER2
HIP2100IB
HI ^HO
LI ^HS
VSS LO
Q3_G
Q3_S
Q4_G
PGND
Q4_S
FIGURE 23C. PUSH-PULL PRIMARY CONTROL
20
FN6762.0
September 2, 2008