Marvell 88EM3278 12V Three-phase Fan Motor Driver PRODUCT OVERVIEW The Marvell® 88EM3278 drives the fan motor using external field-effect transistors (FETs). This device requires a minimum number of external components, and no Hall sensor is needed. Most functions are controlled by the registers, which can be OTP programmable. Alternatively, a microcontroller can communicate/control the 88EM3278 through I2C protocol. The motor driver block integrates the predrivers for the external power FETs and commutation logic. The commutation logic drives a three-phase brushless and sensorless DC motor in full bridge mode. The start-up includes an inductive sense routine followed by a six-step spin up and then hand-over to sine mode. In run mode, the sine drive method minimizes acoustic noise and improves efficiency. The 88EM3278 has an 8-bit ADC. It monitors the temperature information at the DCIN pin to adjust the fan speed accordingly. A PWM signal can also be fed directly into the DCIN pin to control the fan speed. The 88EM3278 includes 2.5V and 5V internal PMOS linear voltage regulators. Other blocks include a bandgap voltage generator, thermal detection and a state machine. V12 D2 D1 2 VPWR PGA12 PGB12 NGB12 PGC12 R2 SCLK 17 R17 SDATA VREG2P5 TACHO 15 DTEST2 14 QFN-24 6 DCIN 7 8 9 10 11 12 +5v R3 +5v R4 TACHO v12 R15 PA C5 PB PC OUTA12 OUTB12 NA 3O Motor OUTC12 R5 NB R6 R7 R8 R9 OUTA12 OUTB12 OUTC12 NC START 13 +5v OUTA12 CTAP12 NC_SEL OUTA12 VREG5 5 GND 4 16 R16 88EM3278 VSNS PWM R1 PWRGND 18 OUTB12 C1 19 OUTC12 +5v 20 VSNS C2 21 OUTB12 3 22 NGC12 V12 23 OUTC12 C3 1 24 NGA12 C4 R10 R12 + Sense Amp - R14 VSNS C6 R13 Fig 1.88EM3278 Block Diagram – 12V Three-phase Fan Motor Driver SPECIAL FEATURES BENEFITS •• 8-14V operation •• Sensorless architecture •• Under voltage detection •• High-efficiency sinusoidal drive •• Integrated pre-drivers for external 12V MOSFET •• Low acoustic noise and low torque ripple •• Sensorless three-phase fan motor control •• DSP-based accurate speed control •• I2C- and SMBus-compatible •• Low external bill of materials cost •• Auto spin-up and closed loop speed control •• Motor pole mismatch compensation to minimize jitter •• Optional open loop mode •• 5-bit torque adjustment for best torque ripple •• Three-phase BEMF detection •• Spin up power supply current control •• 2-bit BEMF hysteresis adjustment •• Inductive sensing for position detect •• 2.5V / 30mA internal regulator •• Speed fault detection •• 5.0V / 20mA internal regulator •• 8-bit ADC for temperature sensing Marvell 88EM3278 APPLICATIONS The Marvell 88EM3278 12V fan motor controller is highly efficient, highly reliable and perfect for low acoustic noise applications including: • Computer server cooling systems • Telecom server cooling systems • Network switch cooling systems • General system cooling • Game consoles, projectors, printers, refrigerators and more EVALUATION BOARD - 12V THREE-PHASE FAN MOTOR DRIVER Fig 2. 88EM3278 (QFN24 5x5mm) 4 Ampere External FET Front and Back Fig 3. 88EM3278 (QFN24 5x5mm) 8 Ampere External FET Front and Back MARVELL GREEN TECHNOLOGY The Marvell 88EM3278 fan controller is part of Marvell’s Green Technology series of products and green fan controllers. As the processing power of central processing units (CPUs) and graphic processing units (GPUs) in today’s servers, desktops and notebooks continues to increase, cooling them is becoming a key issue. A typical server requires one kilowatt of power for processing and an additional one kilowatt for its cooling fans – thereby doubling the power consumption. Marvell’s sensorless fan controllers eliminate external components, thus reducing space and bill of material (BOM) costs. Furthermore, Marvell’s fan controllers’ unique driving method enables efficient power transfer from electricity to motor, greatly improving energy efficiency in cooling fans. Marvell’s green fan controller series includes: • Two-phase Fan Controller – Marvell 88EM8603/88EM8618 • Notebook Fan Controller – Marvell 88EM2269 • Server Fan Controller – Marvell 88EM3278 THE MARVELL ADVANTAGE: Marvell chipsets come with complete reference designs which include board layout designs, software, manufacturing diagnostic tools, documentation, and other items to assist customers with product evaluation and production. Marvell’s worldwide field application engineers collaborate closely with end customers to develop and deliver new leading-edge products for quick time-to-market. Marvell utilizes world-leading semiconductor foundry and packaging services to reliably deliver high-volume and low-cost total solutions. ABOUT MARVELL: Marvell is a leader in storage, communications, and consumer silicon solutions. Marvell’s diverse product portfolio includes switching, transceiver, communications controller, processor, wireless, power management, and storage solutions that power the entire communications infrastructure, including enterprise, metro, home, storage, and digital entertainment solutions. For more information, visit our Web site at www.marvell.com. Marvell Semiconductor, Inc. 5488 Marvell Lane Santa Clara, CA 95054 Phone 408.222.2500 w ww.marvell.com Copyright © 2013. Marvell International Ltd. All rights reserved. Marvell and the Marvell logo are registered trademarks of Marvell. Avastar is a trademark of Marvell. All other trademarks are the property of their respective owners. Marvell_88EM3278-01 1/13