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Analog Devices Inc./Maxim Integrated MAX6651EEE
- Part No.:
- MAX6651EEE
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Motor Drivers, Controllers
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
MAX6651EEE.pdf
- Description:
- IC MOTOR DRIVER 3V-5.5V 16QSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,229
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Product details
Overview
MAX6651EEE from Analog Devices is a 16-pin QSOP fan-speed controller IC that regulates and monitors single 5V/12V brushless fans via SMBus/I2C interface, supports up to four tachometer inputs for parallel fan monitoring, delivers 10mA GPIO sink capability, and operates across -40°C to +85°C for server thermal management.
For engineers reviewing the MAX6651EEE datasheet, MAX6651EEE pinout, MAX6651EEE application, or MAX6651EEE equivalent, this page provides verified pin functions, closed-loop tachometer synchronization logic, GPIO configuration modes (ALERT/FULL-ON/CLOCK), DAC-based feedback control range (0–5.5V), and real-world fan control timing constraints (254kHz ±10% internal oscillator).
Technical Context
The MAX6651EEE implements dual control loops: an analog feedback loop using an 8-bit DAC (0–5.5V output range) to drive external N-channel MOSFETs for linear fan voltage regulation, and a digital tachometer loop that forces measured tach frequency to match a programmable reference by adjusting DAC output in real time. It uses a 254kHz ±10% internal oscillator as clock source unless overridden by GPIO2 configured as external clock input.
Its SMBus/I2C interface supports write byte, read byte, and receive byte protocols with four selectable slave addresses (0x36, 0x3E, 0x90, 0x96), 400kHz max SCL frequency, and glitch-rejected tachometer inputs requiring ≥500μs pulse width. GPIO0–GPIO4 support open-drain operation with 100kΩ internal pullups and configurable roles including active-low ALERT, hardware FULL-ON override, and internal/external clock sync.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 3.0V to 5.5V - powers internal logic and GPIOs; supports direct connection to system 3.3V or 5V rails without LDO. |
| Operating Temperature | -40°C to +85°C - validated for industrial-grade server and telecom chassis environments. |
| Internal Oscillator | 254kHz ±10% - sets tachometer timing base; adjustable via external clock on GPIO2 (MAX6651 only). |
| Tachometer Inputs | Up to 4 (TACH0–TACH3) - each accepts open-collector tach signals; minimum pulse width 500μs. |
| GPIO Sink Current | 10mA per pin - sufficient to directly drive status LEDs or interface with 3.3V/5V logic without external buffers. |
| DAC Resolution | 8-bit monotonic - enables precise 0–5.5V feedback voltage control at FB pin for linear fan voltage regulation. |
| SMBus Speed | Up to 400kHz - compatible with standard I2C fast-mode timing; supports rapid register reads/writes for dynamic speed updates. |
Pinout & Package
MAX6651EEE is housed in a 16-pin QSOP package (5.3mm × 10.2mm, 0.635mm pitch), RoHS-compliant and lead(Pb)-free.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | TACH0 | Primary tachometer input - closes main control loop; threshold VFB+0.5V to VFB+1.5V (5V fan) or VFB+1.0V to VFB+3V (12V fan). |
| 2, 3, 16 | TACH2, TACH3, TACH1 | Additional tachometer inputs - monitor up to three extra fans; identical electrical specs to TACH0. |
| 4 | GND | Analog/digital ground reference - must be low-impedance connection to minimize noise coupling into FB and tach paths. |
| 5 | SDA | Open-drain SMBus/I2C data line - requires external 4.7kΩ pullup to VCC; supports bidirectional communication. |
| 6 | SCL | Open-drain SMBus/I2C clock input - synchronizes all register transfers; max 400kHz frequency. |
| 7, 12 | GPIO4, GPIO3 | General-purpose I/O - open-drain, 10mA sink, 100kΩ internal pullup; configurable as input/output or alarm indicator. |
| 8 | ADD | Slave address select - sets I2C address to 0x36, 0x3E, 0x90, or 0x96 via GND/VCC/no-connect/10kΩ pulldown. |
| 9 | GPIO1 | Hardware full-on override input - active-low signal forces fan to maximum speed independent of software control. |
| 10 | GPIO0 | Programmable alert output - active-low open-drain interrupt signal triggered by tach overflow, min/max output alarms. |
| 11 | GPIO2 | Clock I/O - configurable as internal 254kHz clock output or external clock input for multi-device synchronization. |
| 13 | OUT | Gate driver output - drives external N-MOSFET base/gate; sinks/source current to regulate fan voltage linearly. |
| 14 | VCC | Power supply input - supplies internal logic, DAC, and GPIOs; absolute max 6V, recommended 3.0–5.5V. |
| 15 | FB | Feedback input - connects to MOSFET source/fan low-side; DAC-controlled reference sets regulated fan voltage. |
Key Features
| Feature | Design Value |
|---|---|
| Closed-loop tachometer control | Forces measured tach frequency to match Fan-Speed Register value via real-time DAC adjustment - eliminates manual PID tuning. |
| Four tachometer monitoring channels | Enables synchronized speed control of up to four identical fans in parallel - critical for redundant cooling in RAID and server backplanes. |
| Configurable GPIO roles | GPIO0 = ALERT, GPIO1 = FULL-ON hardware override, GPIO2 = clock sync - reduces need for external logic or microcontroller intervention. |
| Four SMBus slave addresses | Allows up to four MAX6651EEE devices on same bus without address conflict - simplifies multi-zone thermal management in large systems. |
| 8-bit monotonic DAC | Provides 256-step linear feedback voltage control (0–5.5V) - ensures stable, ripple-free fan voltage regulation in open-loop mode. |
Applications
| RAID Storage Arrays | Servers & Workstations |
|---|---|
|
Use Scenario: Redundant cooling for dual-fan RAID enclosures with hot-swap capability and thermal fault reporting. IC Role / Device Role / Timing Role: Fan-speed regulator and tachometer monitor - maintains constant airflow while detecting stalled fans via tach overflow alarm. Use Value: Prevents thermal shutdown during disk rebuild by enforcing minimum fan speed via GPIO1 FULL-ON override when host firmware fails. |
Use Scenario: Multi-zone thermal management in 1U/2U rack servers with CPU, GPU, and power supply cooling zones. IC Role / Device Role / Timing Role: SMBus-addressable fan controller - coordinates speed across up to four fans using shared internal oscillator or GPIO2-synced clocks. Use Value: Reduces acoustic noise by dynamically scaling fan speed to CPU temperature via closed-loop tach feedback, not fixed PWM. |
| Desktop Computers | Telecommunications Equipment |
|
Use Scenario: Quiet thermal management in high-end desktop PCs with discrete GPU and multi-core CPU cooling. IC Role / Device Role / Timing Role: I2C-compatible fan controller - reads tach counts from GPU and CPU fans, adjusts voltage via OUT/FB loop to maintain target RPM. Use Value: Eliminates audible fan whine by avoiding PWM switching; uses linear regulation for smooth, silent speed transitions. |
Use Scenario: Fan control in carrier-grade routers and optical line terminals requiring long-term reliability and fault logging. IC Role / Device Role / Timing Role: Fault-tolerant thermal supervisor - triggers GPIO0 ALERT on tach stall or overtemperature, logs alarm status in SMBus registers. Use Value: Enables remote diagnostics via SMBus alarm registers - no host MCU required to detect fan failure in headless telecom gear. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fan-speed control applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6650EUB+ | 10-pin μMAX package; single tachometer input (TACH0 only); no GPIO2/GPIO3/GPIO4; identical DAC, SMBus, and oscillator specs. | Limited to single-fan systems; lacks multi-fan sync and extended GPIO functionality required for server/RAID use. | Select MAX6650EUB+ only for cost-sensitive, space-constrained designs needing basic closed-loop control of one fan. |
| LM66100DSGT | Single tach input; 6-pin WSON; no GPIOs; fixed 100kHz oscillator; no SMBus - uses analog voltage input for speed setpoint. | No digital interface or alarm reporting; cannot support multi-fan coordination or remote diagnostics. | Choose LM66100DSGT for simple analog-setpoint fan control where I2C bus resources are unavailable or firmware overhead must be minimized. |
Compared with MAX6650EUB+ and LM66100DSGT, the MAX6651EEE uniquely supports synchronized multi-fan control via GPIO2 clocking, four tach inputs for redundancy monitoring, and full SMBus alarm/status visibility - making it the only option for scalable, fault-aware thermal management in enterprise systems.
Availability
MAX6651EEE is available at Aetrix Electronics and suitable for RAID storage arrays, server thermal subsystems, and telecommunications equipment requiring stable component supply, long-lifecycle availability, and guaranteed RoHS compliance.
Supply support for MAX6651EEE includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices is a global semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control.
The MAX6651EEE belongs to Analog Devices' thermal management IC product line, designed specifically for intelligent, SMBus-addressable fan control in high-reliability computing and communications infrastructure.
FAQ
What is the primary function of the MAX6651EEE in a thermal management system?
The MAX6651EEE serves as a closed-loop fan-speed regulator that monitors tachometer signals from up to four 5V/12V brushless fans and dynamically adjusts their voltage via an external MOSFET to maintain a programmed RPM. Its core function is to replace fixed-speed or PWM-based cooling with precise, quiet, and fault-aware thermal control - a capability central to the MAX6651EEE's design for enterprise-grade reliability.
How does the MAX6651EEE handle fan failure detection?
The MAX6651EEE detects fan failure through tachometer overflow alarm: if no pulses are received during the programmed count time (0.25s to 2.0s), the TACH bit in the Alarm Status Register is set and GPIO0 asserts active-low ALERT. This mechanism is hardware-verified and independent of host firmware - ensuring fail-safe response even if the system microcontroller crashes. The MAX6651EEE's tach input threshold and 500μs minimum pulse width guarantee robust noise immunity during fault detection.
Can the MAX6651EEE synchronize multiple fan controllers without an external clock source?
Yes. The MAX6651EEE can synchronize multiple units using its GPIO2 pin configured as an internal clock output (254kHz ±10%), which other MAX6651EEE devices on the same board can accept as an external clock input. This eliminates need for external oscillators or timing ICs - a feature exclusive to the MAX6651EEE among its family and essential for coherent multi-zone cooling in dense server platforms.
What are the valid SMBus slave addresses for the MAX6651EEE and how are they selected?
The MAX6651EEE supports four SMBus slave addresses: 0x36, 0x3E, 0x90, and 0x96. These are selected by the logic state of the ADD pin: grounded (0x90), tied to VCC (0x96), left floating or pulled down with 100kΩ (0x36), or pulled down with 10kΩ (0x3E). This pin-strapping scheme allows up to four MAX6651EEE devices to coexist on a single SMBus without address collision - a key requirement for scalable thermal management in blade servers.
Does the MAX6651EEE require external components for basic operation?
Yes. The MAX6651EEE requires an external N-channel MOSFET (driven by OUT pin) and feedback resistor network (connected to FB pin) to form the fan voltage regulation loop. It also needs pullup resistors on SDA/SCL lines (typically 4.7kΩ) and a bypass capacitor on VCC (≥1μF). Unlike integrated fan drivers, the MAX6651EEE's external FET architecture enables selection of optimal RDS(ON) and voltage rating for 5V or 12V fans - a deliberate design choice reflected in its datasheet-recommended MOSFET selection guidelines.
MAX6651EEE Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Motor Type - Stepper:
- -
- Motor Type - AC, DC:
- Brushless DC (BLDC)
- Function:
- Controller - Speed
- Output Configuration:
- Pre-Driver - Low Side
- Interface:
- I2C
- Technology:
- -
- Step Resolution:
- -
- Applications:
- Fan Controller
- Current - Output:
- -
- Voltage - Supply:
- 3V ~ 5.5V
- Voltage - Load:
- -
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QSOP
MAX6651EEE FAQ
1.How can I place an order for MAX6651EEE through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6651EEE on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for MAX6651EEE reliable?
The price and inventory of MAX6651EEE are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6651EEE is usually 5 days.
3.What payment methods are accepted for MAX6651EEE?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6651EEE transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6651EEE?
MAX6651EEE orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6651EEE order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for MAX6651EEE?
For technical support, including MAX6651EEE datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6651EEE requirements.
6.How does Aetrix verify that MAX6651EEE is sourced from the original manufacturer or authorized distributors?
All MAX6651EEE products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MAX6651EEE meets industry standards.
7.What is the process for return or replacement of MAX6651EEE?
All MAX6651EEE units undergo pre-shipment inspection (PSI). If there is an issue with MAX6651EEE, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The MAX6651EEE part is unused and in its original packaging.
Return procedure for MAX6651EEE:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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