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Analog Devices Inc./Maxim Integrated MAX6645BAFAUB+T
- Part No.:
- MAX6645BAFAUB+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Thermal Management
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
MAX6645BAFAUB+T.pdf
- Description:
- IC CNTRLR FAN SPEED 10-UMAX
- Quantity:
- Payment:
- Shipping:
Inventory:2,989
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Product details
Overview
The MAX6645BAFAUB+T from Analog Devices is a factory-programmed, dual-channel remote temperature monitoring IC with automatic PWM fan-speed control, 32Hz PWM output frequency, ±2°C remote temperature accuracy (20°C–100°C), and 10-pin μMAX® package. It measures two external diode-connected transistors for server thermal management and drives external MOSFETs to modulate fan power supply voltage.
For engineers reviewing the MAX6645BAFAUB+T datasheet, MAX6645BAFAUB+T pinout, MAX6645BAFAUB+T application, or MAX6645BAFAUB+T equivalent, key selection criteria include factory-set trip thresholds, dual-diode sensing capability, open-drain FANFAIL/OT outputs, tachometer/current-sense/locked-rotor fan-fail detection modes, and compatibility with 3.0V–5.5V supply rails in high-density compute platforms.
Technical Context
The MAX6645BAFAUB+T implements an integrating ADC architecture optimized for pn-junction temperature sensing, with dedicated DXP1/DXP2 inputs sourcing 80–120µA for remote diode biasing. It performs temperature comparisons once per second for overtemperature (OT) and once every 4 seconds for fan-control thresholds (THIGH/TLOW), using the larger of two measured temperatures to drive PWM duty-cycle adjustments in 1.5% increments.
Its PWM_OUT operates at a fixed 32Hz frequency with controlled rate-of-change (max 0.4%/s), while FANFAIL detection activates only during 100% duty-cycle periods (spin-up or sustained high-temp operation), counting tachometer pulses or monitoring current-sense waveforms across configurable FAN_IN1/FAN_IN2 inputs based on TACHSET logic state.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| PWM Frequency | 32Hz - Fixed low-frequency output compatible with standard DC fans and avoids audible resonance in cooling systems. |
| Remote Temp Accuracy | ±2°C (20°C–100°C) - Enables precise thermal throttling in servers without calibration overhead. |
| Supply Voltage Range | 3.0V to 5.5V - Supports direct connection to common logic rails without LDO regulation. |
| Operating Current | 0.5mA typical - Minimizes system-level power budget impact in always-on thermal monitoring. |
| Digital Output Drive | FANFAIL/OT: open-drain, 6mA sink - Allows flexible pull-up to 5.5V rail independent of VDD for interfacing with higher-voltage alarm logic. |
| Temperature Update Rate | 1Hz measurement rate - Provides responsive thermal feedback while avoiding excessive noise sensitivity. |
| Startup Delay | 0.5s - Prevents inrush current surges during power-on by delaying initial fan activation. |
Pinout & Package
Package: 10-pin μMAX® (U10-2), 3mm × 3mm, 0.5mm pitch, exposed pad for thermal enhancement.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | FANFAIL | Active-low open-drain fan-failure alarm; asserts only during 100% PWM duty cycle when fan speed falls below 480rpm (2-pulse/rev). |
| 2 | TACHSET | Configures FAN_IN1/FAN_IN2 sensing mode: VDD = tachometer, GND = current sense, floating = locked rotor. |
| 3 | DXP2 | Current source + A/D positive input for second remote diode; requires 2200pF capacitor to GND for noise filtering. |
| 4 | GND | Analog/digital ground reference; connects to exposed thermal pad for improved heat dissipation. |
| 5 | DXP1 | Current source + A/D positive input for first remote diode; identical function and filtering requirement as DXP2. |
| 6 | VDD | 3.0V–5.5V power supply input; bypassed with 0.1µF capacitor to GND near pin for stable ADC operation. |
| 7 | PWM_OUT | Open-drain PWM output driving external n-channel MOSFET gate; requires external pull-up to ≤5.5V. |
| 8 | FAN_IN2 | Fan failure sense input; supports tachometer pulses, current-sense AC waveform, or locked-rotor logic signal. |
| 9 | FAN_IN1 | Identical dual-channel fan failure sense input; enables independent monitoring of two cooling fans. |
| 10 | OT | Active-low open-drain overtemperature alarm; asserts when either remote diode exceeds factory-set TOVERT threshold. |
Key Features
| Feature | Design Value |
|---|---|
| Dual remote diode sensing | Simultaneously monitors two external transistors (e.g., CPU/GPU diodes) to determine worst-case thermal condition for fan control. |
| Factory-programmed thresholds | Eliminates external resistor networks or configuration pins-THIGH/TLOW/TOVERT are permanently set at wafer level for consistent BOM and layout. |
| Multi-mode fan-fail detection | Supports tachometer pulse counting, current-sense waveform analysis, and locked-rotor logic via TACHSET-selectable FAN_IN inputs. |
| Controlled PWM ramp rate | Limits duty-cycle change to ≤1.5% per 4s interval, minimizing acoustic noise during fan speed transitions in quiet environments. |
| Spin-up time enforcement | Applies 100% PWM duty cycle for 8s at startup to ensure reliable fan motor engagement before transitioning to temperature-based control. |
Applications
| Server Rack Thermal Management | Storage Array Fan Control |
|---|---|
Use Scenario: Real-time monitoring of CPU and GPU die temperatures in 1U/2U rack-mount servers with dual-fan redundancy. IC Role / Device Role / Timing Role: Dual-channel temperature sensor and PWM controller that selects maximum temperature between two diodes to drive fan speed, with OT triggering system shutdown if either exceeds 95°C. Use Value: Eliminates need for microcontroller-based thermal loops, reduces firmware complexity, and ensures deterministic fan response within 4s of temperature crossing THIGH. |
Use Scenario: Active cooling control for multi-bay NAS enclosures with hot-swap SATA drives generating localized heat gradients. IC Role / Device Role / Timing Role: Measures temperature at front and rear drive bays via discrete transistors, adjusts dual-fan speeds independently using FAN_IN1/FAN_IN2 fault detection. Use Value: Maintains <±2°C thermal uniformity across drive array while detecting stalled fans before RAID degradation occurs. |
| Workstation GPU Cooling | Network Switch Chassis Thermal Regulation |
Use Scenario: Compact thermal management for high-TDP workstation GPUs where PCB space limits use of discrete controllers. IC Role / Device Role / Timing Role: Interfaces directly with GPU's on-die thermal diode and secondary board-level transistor to generate 32Hz PWM for blower-style fan. Use Value: Achieves 0.5s startup delay and 8s spin-up to prevent GPU VRM voltage droop during cold boot, with ±2°C accuracy enabling tighter thermal margins. |
Use Scenario: Fan-speed optimization in Layer 3 enterprise switches with multiple ASICs generating variable thermal loads under traffic bursts. IC Role / Device Role / Timing Role: Monitors temperature at switch fabric and packet processor locations, uses FANFAIL to isolate failed fans in N+1 redundant cooling modules. Use Value: Reduces acoustic noise by 12dB(A) versus fixed-speed fans while maintaining ASIC junction temperature <95°C under full line-rate traffic. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar automatic PWM fan-speed control applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6644LBAAEE | 16-pin QSOP; pin-selectable THIGH/TLOW/TOVERT via TH1/TH2/TL1/TL2/OT1/OT2 inputs; supports same 32Hz PWM and dual-diode sensing. | Requires external resistor network or GPIO configuration for trip points; better suited for prototyping or multi-configurable SKUs. | Select MAX6644LBAAEE when field-upgradable thermal thresholds or mixed-batch production are required. |
| LM96000CIMTX/NOPB | 32-pin TSSOP; integrates SMBus interface, 12-bit ADC, and programmable registers; remote accuracy ±1.5°C; no built-in PWM generator (requires external MCU). | Enables dynamic threshold updates and telemetry reporting via I²C; used where centralized thermal management firmware exists. | Select LM96000CIMTX/NOPB when system-level thermal policy coordination across multiple zones is needed. |
Compared with MAX6644LBAAEE, the MAX6645BAFAUB+T trades pin configurability for smaller footprint and guaranteed consistency; compared with LM96000CIMTX/NOPB, it delivers autonomous closed-loop fan control without software intervention but lacks digital communication or fine-grained register access.
Availability
The MAX6645BAFAUB+T is available at Aetrix Electronics and suitable for server thermal management, storage array cooling, workstation GPU regulation, and network switch chassis applications requiring stable component supply and long-term industrial lifecycle support.
Supply support for MAX6645BAFAUB+T 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, headquartered in Wilmington, MA, with design centers worldwide.
The MAX6645BAFAUB+T belongs to the MAX664x family of autonomous fan-speed controllers, designed specifically for thermally constrained computing platforms where deterministic, low-noise, hardware-based thermal regulation is critical.
FAQ
What is the operating temperature range of the MAX6645BAFAUB+T?
The MAX6645BAFAUB+T operates across -40°C to +125°C ambient temperature, with junction temperature rated to +150°C. This range supports deployment in high-heat environments such as server racks and industrial network switches where airflow may be restricted and ambient temperatures exceed 70°C.
Does the MAX6645BAFAUB+T require external components for basic operation?
Yes, the MAX6645BAFAUB+T requires a 0.1µF bypass capacitor on VDD, 2200pF capacitors from DXP1 and DXP2 to GND for noise filtering, and external pull-up resistors on PWM_OUT and OT/FANFAIL outputs. No external resistors are needed for trip thresholds since they are factory-programmed.
How does the MAX6645BAFAUB+T detect fan failure?
The MAX6645BAFAUB+T detects fan failure during 100% PWM duty-cycle periods by counting tachometer pulses on FAN_IN1/FAN_IN2 (≥32 pulses in 2s = 480rpm), analyzing current-sense resistor waveforms, or monitoring locked-rotor logic signals-all selectable via the TACHSET pin configuration.
Can the MAX6645BAFAUB+T monitor internal die temperature?
No, the MAX6645BAFAUB+T is configured exclusively for dual external diode sensing (DXP1/DXP2). Unlike the MAX6643, it does not include an internal temperature sensor; its thermal feedback relies entirely on externally connected transistors or IC diodes.
What is the PWM output frequency and why is it fixed at 32Hz?
The MAX6645BAFAUB+T generates a fixed 32Hz PWM output to match the mechanical response time of standard DC cooling fans while avoiding audible whine. This frequency balances efficient transistor switching with minimal acoustic noise and eliminates need for external timing components.
MAX6645BAFAUB+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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:
- 10-uMAX/uSOP
MAX6645BAFAUB+T FAQ
1.How can I place an order for MAX6645BAFAUB+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6645BAFAUB+T 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 MAX6645BAFAUB+T reliable?
The price and inventory of MAX6645BAFAUB+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6645BAFAUB+T is usually 5 days.
3.What payment methods are accepted for MAX6645BAFAUB+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6645BAFAUB+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6645BAFAUB+T?
MAX6645BAFAUB+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6645BAFAUB+T 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 MAX6645BAFAUB+T?
For technical support, including MAX6645BAFAUB+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6645BAFAUB+T requirements.
6.How does Aetrix verify that MAX6645BAFAUB+T is sourced from the original manufacturer or authorized distributors?
All MAX6645BAFAUB+T 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 MAX6645BAFAUB+T meets industry standards.
7.What is the process for return or replacement of MAX6645BAFAUB+T?
All MAX6645BAFAUB+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX6645BAFAUB+T, 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 MAX6645BAFAUB+T part is unused and in its original packaging.
Return procedure for MAX6645BAFAUB+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MAX6645BAFAUB+T Tags
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