IR3551 Datasheet, PDF (1/22 Pages) International Rectifier – The IR3551 integrated PowIRstage® is a synchronous buck gate driver co-packed with a control MOSFET and a synchronous MOSFET with integrated Schottky diode.

50A Integrated PowIRstage® _IR3551
FEATURES
 Peak efficiency up to 94.5% at 1.2V
 Integrated driver, control MOSFET, synchronous
MOSFET and Schottky diode
 Input voltage (VIN) operating range up to 15V
 Output voltage range from 0.25V up to 3.3V
 Output current capability of 50A DC
 Operation up to 1.0MHz
 Integrated current sense amplifier
 VCC under voltage lockout
 Thermal flag
 Body-Braking® load transient support
 Diode-emulation high efficiency mode
 Compatible with 3.3V PWM logic and VCC tolerant
 Compliant with Intel DrMOS V4.0
 PCB footprint compatible with IR3550 and IR3553
 Efficient dual sided cooling
 Small 5mm x 6mm x 0.9mm PQFN package
 Lead free RoHS compliant package
APPLICATIONS
 Voltage Regulators for CPUs, GPUs, and DDR
memory arrays
 High current, low profile DC-DC converters
BASIC APPLICATION
VCC
4.5V to 7V
PHSFLT#
PWM
BBRK#
REFIN
IOUT
IR3551
VCC
VIN
BOOST
PHSFLT#
PWM
BBRK#
REFIN
IOUT
LGND
SW
CSIN+
CSIN-
PGND
VIN
4.5V to 15V
VOUT
Figure 1: IR3551 Basic Application Circuit
DESCRIPTION
The IR3551 integrated PowIRstage® is a synchronous buck
gate driver co-packed with a control MOSFET and a
synchronous MOSFET with integrated Schottky diode. It is
optimized internally for PCB layout, heat transfer and
driver/MOSFET timing. Custom designed gate driver and
MOSFET combination enables higher efficiency at lower
output voltages required by cutting edge CPU, GPU and
DDR memory designs.
Up to 1.0MHz switching frequency enables high
performance transient response, allowing miniaturization
of output inductors, as well as input and output capacitors
while maintaining industry leading efficiency. The IR3551’s
superior efficiency enables smallest size and lower solution
cost. The IR3551 PCB footprint is compatible with the
IR3550 (60A) and the IR3553 (40A).
Integrated current sense amplifier achieves superior
current sense accuracy and signal to noise ratio vs. best-in-
class controller based Inductor DCR sense methods.
The IR3551 incorporates the Body-Braking® feature which
enables reduction of output capacitors. Synchronous diode
emulation mode in the IR3551 removes the zero-current
detection burden from the PWM controller and increases
system light-load efficiency.
The IR3551 is optimized specifically for CPU core power
delivery in server applications. The ability to meet the
stringent requirements of the server market also makes
the IR3551 ideally suited to powering GPU and DDR
memory designs and other high current applications.
95
20
93
18
91
16
89
14
87
12
85
10
83
8
81
6
79
4
77
2
75
0
0
5 10 15 20 25 30 35 40 45 50
Output Current (A)
Figure 2: Typical IR3551 Efficiency & Power Loss (See Note 2 on Page 8)
1 September 10, 2012 | FINAL DATASHEET