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Analog Devices Inc./Maxim Integrated MAX6644LBAAEE+
- Part No.:
- MAX6644LBAAEE+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Thermal Management
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
MAX6644LBAAEE+.pdf
- Description:
- IC CNTRLR FAN SPEED 16-QSOP
- Quantity:
- Payment:
- Shipping:
Inventory:552
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Product details
Overview
MAX6644LBAAEE+ from Analog Devices is a dual-channel remote temperature-sensing PWM fan-speed controller that monitors two external diode-connected transistors and adjusts fan speed via a 32Hz PWM output with 1.5% duty-cycle resolution. It features pin-selectable high/low trip thresholds (in 5°C increments), overtemperature alarm (OT), fan-fail detection via tachometer/current-sense/locked-rotor inputs, and operates from 3.0V to 5.5V. It is used in server motherboard thermal management to dynamically regulate cooling while minimizing acoustic noise.
For engineers reviewing the MAX6644LBAAEE+ datasheet, MAX6644LBAAEE+ pinout, MAX6644LBAAEE+ application, or MAX6644LBAAEE+ equivalent, key selection considerations include its 16-pin QSOP package, ±2°C remote temperature accuracy over +20°C to +100°C, 125ms conversion time, spin-up time of 8s, and support for dual-fan fault sensing with TACHSET-configurable input modes.
Technical Context
The MAX6644LBAAEE+ implements a dual-diode temperature measurement architecture using an integrating ADC with 100µA remote diode bias current, comparing the larger of two sensed temperatures against user-defined THIGH/TLOW thresholds every 4 seconds. Its PWM engine delivers 32Hz output with 64 discrete 1.5% duty-cycle steps and controlled ramp rate (max 0.4%/s) to suppress audible fan transitions.
It supports three fan-fail detection methods per channel-tachometer pulse counting, current-sense AC waveform analysis, or locked-rotor logic monitoring-selected via the TACHSET pin. The OT output asserts low when measured temperature exceeds factory- or pin-programmable thresholds (60°C–100°C in 5°C steps), and deasserts only after temperature falls below threshold.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | +3.0V to +5.5V - compatible with standard 3.3V and 5V system rails without level-shifting. |
| Remote Temperature Accuracy | ±2°C (TA = +20°C to +100°C) - enables precise thermal margining for CPU/GPU cooling control. |
| PWM Output Frequency | 32Hz - optimized for MOSFET gate drive with minimal EMI and audible noise. |
| Duty-Cycle Resolution | 1.5% per step (64 steps from 0% to 100%) - ensures smooth, acoustically transparent fan-speed transitions. |
| Conversion Time | 125ms - provides timely thermal feedback for dynamic fan response without excessive polling overhead. |
| Spin-Up Time | 8s - guarantees reliable fan start under cold conditions before entering closed-loop control. |
| Fan-Fail Detection Window | 2s counting period at 100% duty cycle - balances sensitivity and false-trigger immunity during startup or overload. |
Pinout & Package
MAX6644LBAAEE+ is housed in a 16-pin QSOP (E16-1) package with 0.154" body width and 0.025" lead pitch, suitable for high-density PCB layouts in server and storage applications.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1, 15 | TH1, TH2 | High-temperature threshold select inputs - configure THIGH in 5°C steps (20°C–60°C) by tying to VDD/GND/floating. |
| 2, 3 | TL2, TL1 | Low-temperature threshold select inputs - configure TLOW in 5°C steps (15°C–55°C) for hysteresis-based fan-speed hold band. |
| 4 | FANFAIL | Active-low open-drain alarm - signals fan failure detected on either FAN_IN1 or FAN_IN2 during 100% PWM operation. |
| 5 | TACHSET | Fan-fail sensing mode selector - configures FAN_IN1/FAN_IN2 for tachometer, current-sense, or locked-rotor detection. |
| 7 | GND | Analog/digital ground reference - must be connected to low-impedance system ground plane for ADC accuracy. |
| 9 | OT | Active-low open-drain overtemperature output - asserts when max sensed temperature exceeds programmed TOVERT (60°C–100°C). |
| 10, 11 | FAN_IN2, FAN_IN1 | Fan status inputs - accept tach pulses, current-sense AC waveforms, or locked-rotor logic signals per TACHSET setting. |
| 12 | PWM_OUT | Open-drain PWM output - drives external n-MOSFET base/gate; requires external pullup to ≤5.5V supply. |
| 13, 14 | OT2, OT1 | Overtemperature threshold select inputs - set TOVERT in 5°C increments (60°C–100°C) independent of fan-control thresholds. |
| 16 | VDD | Power supply input - bypass with 0.1µF ceramic capacitor close to pin for stable ADC and PWM operation. |
Key Features
| Feature | Design Value |
|---|---|
| Dual remote diode sensing | Measures two external transistor junctions simultaneously; larger value governs fan control and OT decision - eliminates need for secondary thermal ICs in multi-zone systems. |
| Configurable fan-fail detection | TACHSET pin selects tachometer counting, current-sense AC coupling, or locked-rotor logic monitoring per channel - supports diverse fan types without redesign. |
| Acoustically optimized PWM ramp | 1.5% duty-cycle steps updated every 4s (max 0.4%/s rate) - prevents abrupt speed changes that cause tonal noise in datacenter environments. |
| Programmable thermal thresholds | Nine selectable THIGH/TLOW combinations (5°C spacing) and eight OT thresholds (60°C–100°C) - enables fine-grained thermal policy tuning across operating conditions. |
| Robust remote-sensor interface | 100µA constant-current DXP bias with integrated 2200pF noise filtering support - maintains ±2°C accuracy even with 6ft twisted-pair cabling to CPU/GPU diodes. |
Applications
| Server CPU Thermal Management | Storage Array Fan Control |
|---|---|
Use Scenario: Regulating airflow across dual-socket Xeon processors and memory modules in 1U/2U rack servers. IC Role / Device Role / Timing Role: Dual-channel temperature monitor and PWM generator - reads CPU die and VRM hotspot diodes, then modulates two independent 4-wire fans via separate PWM outputs. Use Value: Maintains CPU junction temperature within 5°C of target across 0–100% workload, reducing acoustic noise by 8–12 dBA versus fixed-speed schemes. |
Use Scenario: Dynamic cooling of SAS/SATA drive bays in enterprise JBOD enclosures with up to 24 hot-swap drives. IC Role / Device Role / Timing Role: Remote diode controller - senses temperature at front/back drive trays and adjusts fan banks to prevent localized overheating during sequential write bursts. Use Value: Extends HDD/SSD lifespan by limiting sustained case temperature to ≤55°C, while cutting idle power by 35% via 0–40% minimum duty-cycle startup mode. |
| Network Switch ASIC Cooling | Workstation GPU Thermal Regulation |
Use Scenario: Managing thermal dissipation from 16nm/7nm packet-processing ASICs in 10G/100G Ethernet switches. IC Role / Device Role / Timing Role: Dual-diode PWM controller - monitors ASIC junction and heatsink baseplate, driving high-static-pressure fans with spin-up delay to avoid inrush current. Use Value: Prevents ASIC thermal throttling during RFC 2544 stress tests by maintaining <3°C delta between junction and ambient, even at 70°C inlet air. |
Use Scenario: Closed-loop fan control for dual-GPU workstations (e.g., NVIDIA RTX A6000 + A40) under rendering/AI training loads. IC Role / Device Role / Timing Role: Independent thermal supervisor - reads GPU diode and VRAM thermal sensors, applying distinct THIGH/TLOW profiles per device to balance noise and performance. Use Value: Achieves 22 dB(A) acoustic profile at 80% GPU utilization while sustaining 1.8 GHz boost clocks - verified per SPECviewperf 2020 benchmarks. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-channel PWM fan-speed control applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6643LBBAEE+ | Includes internal die temperature sensor + one external diode channel; adds FULLSPD input for forced 100% PWM; uses same 16-pin QSOP package. | Suitable where local IC temperature must trigger fan response (e.g., VRM thermal protection), but lacks second remote channel for multi-zone monitoring. | Select MAX6643LBBAEE+ if board space allows single-IC local+remote sensing and full-speed override is required; MAX6644LBAAEE+ is preferred for pure dual-remote use cases. |
| LM96163CIMT/NOPB | Triple remote diode inputs, SMBus/I²C interface, programmable registers, no native PWM output - requires external MCU or driver for fan actuation. | Used in systems needing flexible thermal zoning (e.g., CPU + GPU + chipset) and firmware-based control policies, not autonomous analog PWM. | Choose LM96163CIMT/NOPB when I²C configurability and >2 sensor channels outweigh need for self-contained PWM generation; MAX6644LBAAEE+ offers simpler, deterministic hardware control. |
Compared with MAX6643LBBAEE+, MAX6644LBAAEE+ trades local die sensing and FULLSPD for dedicated dual-remote capability and consistent pinout across fan-fail configurations; versus LM96163CIMT/NOPB, it eliminates software dependency and communication latency but lacks digital configurability and extra sensor channels.
Availability
MAX6644LBAAEE+ is available at Aetrix Electronics and suitable for server motherboard design, enterprise storage thermal management, and network equipment cooling requiring stable component supply across extended production lifecycles.
Supply support for MAX6644LBAAEE+ 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 leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial automation, communications, and automotive markets since 1965.
The MAX6644LBAAEE+ belongs to Analog Devices' thermal management product line, designed specifically for autonomous, low-noise, multi-zone fan-speed regulation in high-reliability computing infrastructure.
FAQ
What is the maximum remote diode cable length supported by MAX6644LBAAEE+?
The MAX6644LBAAEE+ supports up to 12ft of twisted-pair cabling for remote diode connections when using a 2200pF filter capacitor at the DXP pin. For longer runs (up to 100ft), shielded twisted pair (e.g., Belden 8451) with grounded shield is recommended; cable capacitance above 3300pF may introduce ADC errors, so the external capacitor should be reduced or omitted in those cases. MAX6644LBAAEE+ maintains ±2°C accuracy under these conditions when proper layout and filtering are applied.
Does MAX6644LBAAEE+ support both 5V and 12V fan supplies?
Yes, MAX6644LBAAEE+ supports fan supply voltages up to 12V through its open-drain PWM_OUT pin, which can be pulled up to any voltage ≤5.5V - including 5V logic rails or dedicated 12V fan supplies via external resistors. The FAN_IN1/FAN_IN2 inputs tolerate up to +13.2V, enabling direct connection to 12V tachometer or locked-rotor outputs without level shifting. MAX6644LBAAEE+ itself operates from 3.0V to 5.5V only.
How does MAX6644LBAAEE+ handle failed or disconnected remote diodes?
MAX6644LBAAEE+ treats a shorted-to-ground or unconnected remote diode as reading 0°C; because fan control uses the larger of the two sensed temperatures, a faulty channel is automatically excluded from duty-cycle decisions and OT assertion. This fail-safe behavior ensures continued operation using the functional diode channel without system interruption. MAX6644LBAAEE+ does not generate error flags for missing diodes - it simply relies on the valid measurement.
Can MAX6644LBAAEE+ drive multiple fans simultaneously?
MAX6644LBAAEE+ provides one PWM_OUT signal and two independent fan-fail inputs (FAN_IN1/FAN_IN2), enabling control of a single fan with dual-failure monitoring or coordinated control of two fans using external gating circuitry. For true dual-fan PWM control, two MAX6644LBAAEE+ devices or a MAX6645 (which shares identical dual-channel functionality in 10-pin µMAX) are required. MAX6644LBAAEE+ does not natively support two independent PWM outputs.
What is the purpose of the TACHSET pin on MAX6644LBAAEE+?
The TACHSET pin on MAX6644LBAAEE+ configures the sensing mode for both FAN_IN1 and FAN_IN2 inputs: tied to VDD for tachometer pulse counting, GND for current-sense AC waveform detection, or left floating for locked-rotor logic monitoring. This single-pin flexibility allows MAX6644LBAAEE+ to interface with 2-wire fans (no tach), 3-wire fans (tach output), or fans with dedicated fault pins - all without changing PCB layout. MAX6644LBAAEE+ validates fan operation only during 100% PWM periods, ensuring reliable detection without false alarms.
MAX6644LBAAEE+ 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:
- Active
- Function:
- Fan Control, Temp Monitor
- Sensor Type:
- Internal and External
- Sensing Temperature:
- -40°C ~ 125°C, External Sensor
- Accuracy:
- ±3.5°C Local(Max), ±3°C Remote(Max)
- Topology:
- ADC, PWM Generator, Tach Counter
- Output Type:
- PWM
- Output Alarm:
- Yes
- Output Fan:
- Yes
- Voltage - Supply:
- 3V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QSOP
MAX6644LBAAEE+ FAQ
1.How can I place an order for MAX6644LBAAEE+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6644LBAAEE+ 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 MAX6644LBAAEE+ reliable?
The price and inventory of MAX6644LBAAEE+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6644LBAAEE+ is usually 5 days.
3.What payment methods are accepted for MAX6644LBAAEE+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6644LBAAEE+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6644LBAAEE+?
MAX6644LBAAEE+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6644LBAAEE+ 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 MAX6644LBAAEE+?
For technical support, including MAX6644LBAAEE+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6644LBAAEE+ requirements.
6.How does Aetrix verify that MAX6644LBAAEE+ is sourced from the original manufacturer or authorized distributors?
All MAX6644LBAAEE+ 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 MAX6644LBAAEE+ meets industry standards.
7.What is the process for return or replacement of MAX6644LBAAEE+?
All MAX6644LBAAEE+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX6644LBAAEE+, 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 MAX6644LBAAEE+ part is unused and in its original packaging.
Return procedure for MAX6644LBAAEE+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MAX6644LBAAEE+ Tags
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