50A Integrated PowIRstage IR3551 FEATURES DESCRIPTION The IR3551 integrated PowIRstage is a synchronous buck Peak efficiency up to 94.5% at 1.2V gate driver co-packed with a control MOSFET and a Integrated driver, control MOSFET, synchronous synchronous MOSFET with integrated Schottky diode. It is MOSFET and Schottky diode optimized internally for PCB layout, heat transfer and Input voltage (VIN) operating range up to 15V driver/MOSFET timing. Custom designed gate driver and MOSFET combination enables higher efficiency at lower Output voltage range from 0.25V to Vcc-2.5V, or to output voltages required by cutting edge CPU, GPU and 5.5V if internal current sense amplifier is not used DDR memory designs. Output current capability of 50A DC Up to 1.0MHz switching frequency enables high Operation up to 1.0MHz performance transient response, allowing miniaturization Integrated current sense amplifier of output inductors, as well as input and output capacitors VCC under voltage lockout while maintaining industry leading efficiency. The IR3551s superior efficiency enables smallest size and lower solution Thermal flag cost. The IR3551 PCB footprint is compatible with the Body-Braking load transient support IR3550 (60A) and the IR3553 (40A). Diode-emulation high efficiency mode Integrated current sense amplifier achieves superior Compatible with 3.3V PWM logic and VCC tolerant current sense accuracy and signal to noise ratio vs. best-in- Compliant with Intel DrMOS V4.0 class controller based Inductor DCR sense methods. PCB footprint compatible with IR3550 and IR3553 The IR3551 incorporates the Body-Braking feature which Efficient dual sided cooling enables reduction of output capacitors. Synchronous diode emulation mode in the IR3551 removes the zero-current Small 5mm x 6mm x 0.9mm PQFN package detection burden from the PWM controller and increases Lead free RoHS compliant package system light-load efficiency. The IR3551 is optimized specifically for CPU core power APPLICATIONS delivery in server applications. The ability to meet the stringent requirements of the server market also makes Voltage Regulators for CPUs, GPUs, and DDR memory arrays the IR3551 ideally suited to powering GPU and DDR memory designs and other high current applications. High current, low profile DC-DC converters 95 20 BASIC APPLICATION 93 18 91 16 IR3551 89 14 VIN VCC VCC VIN 4.5V to 15V 4.5V to 7V 87 12 BOOST 85 10 VOUT 83 8 PHSFLT PHSFLT SW 81 6 PWM PWM 79 4 BBRK BBRK 77 2 REFIN REFIN CSIN+ IOUT IOUT CSIN- 75 0 0 5 10 15 20 25 30 35 40 45 50 LGND PGND Output Current (A) Figure 2: Typical IR3551 Efficiency & Power Loss (See Note 2 on Page 8) Figure 1: IR3551 Basic Application Circuit 1 July 16, 2013 DATASHEET V3.2 Efficiency (%) Power Loss (W)50A Integrated PowIRstage IR3551 PINOUT DIAGRAM ORDERING INFORMATION Package Tape & Reel Qty Part Number PQFN, 28 Lead 3000 IR3551MTRPBF 5mm x 6mm Package Qty Part Number PQFN, 28 Lead 100 IR3551MPBF 5mm x 6mm Figure 3: IR3551 Pin Diagram, Top View TYPICAL APPLICATION DIAGRAM VIN VCC C3 C1 4.5V to 7V C2 4.5V to 15V 3 1uF 16-19 0.22uF 10uF x 2 R1 VCC VIN IR3551 10k 21 PHSFLT PHSFLT 20 C5 BOOST L1 22 PWM 0.22uF PWM 150nH C6 C7 Gate 22uF 470uF 23 BBRK SW BBRK Drivers VOUT C9 6-13 and 22nF Optional for Current 24 LGND diode emulation Sense R2 C4 setup 2.49k 0.22uF 25 Amplifier REFIN REFIN 14, 15 PGND C8 26 IOUT PGND 1nF 4 IOUT TGND CSIN- CSIN+ 27 1 2 No Connect Figure 4: Application Circuit with Current Sense Amplifier 2 July 16, 2013 DATASHEET V3.2