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Analog Devices Inc./Maxim Integrated MAX6643LBFAEE+T
- Part No.:
- MAX6643LBFAEE+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Thermal Management
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
MAX6643LBFAEE+T.pdf
- Description:
- IC CTLR PWM FAN-SPEED 16QSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,967
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Product details
Overview
MAX6643LBFAEE+T from Analog Devices is a 16-pin QSOP automatic PWM fan-speed controller that monitors local die temperature and one external diode-connected transistor, adjusts fan speed in 1.5% duty-cycle steps at 32Hz, and features FULLSPD input, FANFAIL alarm, and OT overtemperature output for server and networking thermal management.
For engineers reviewing the MAX6643LBFAEE+T datasheet, MAX6643LBFAEE+T pinout, MAX6643LBFAEE+T application, or MAX6643LBFAEE+T equivalent, this page delivers verified functional identity, confirmed 16-pin QSOP package mapping, validated 9 selectable trip points (5°C increments), real-world fan-fail detection modes, and two manufacturer-confirmed alternative options for thermal control systems requiring acoustic-noise-sensitive cooling.
Technical Context
The MAX6643LBFAEE+T implements dual-sensor thermal feedback with internal ADC measuring local junction temperature and remote diode voltage using a switched-current source; it compares the larger of the two temperatures against user-configurable THIGH/TLOW thresholds every 4 seconds to drive PWM_OUT with 64 discrete duty-cycle steps (0–100%).
Its fan-control logic enforces a 1.5% maximum duty-cycle change per 4s interval and includes spin-up time (8s) and startup delay (0.5s); the FULLSPD input forces immediate 100% PWM duty cycle, while FANFAIL asserts low only during 100%-duty-cycle periods after detecting <32 tach pulses in 2s or sustained locked-rotor signal.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | +3.0V to +5.5V - supports direct interface with 3.3V or 5V system rails without level-shifting. |
| PWM Output Frequency | 32Hz ±0.5Hz - acoustically optimized frequency minimizing audible fan whine during speed transitions. |
| Temperature Accuracy | ±2°C (local, TA = +10°C to +70°C); ±2°C (remote, TRJ = +20°C to +100°C) - enables reliable thermal margining in servers and storage enclosures. |
| Duty-Cycle Resolution | 64 steps (1.5% per step) - provides fine-grained fan speed control to balance cooling performance and acoustic noise. |
| Fan-Fail Detection Threshold | <32 tach pulses/2s (equivalent to ~480rpm for 2-pulse/rev fan) - ensures robust failure detection without false alarms during transient load changes. |
| Operating Current | 0.5mA typical (no load, 50% duty cycle) - minimizes power impact on low-power thermal management subsystems. |
| Overtemperature Response | OT asserts low when measured temperature exceeds factory- or pin-selectable threshold (60°C–100°C in 5°C steps) - provides fail-safe shutdown signaling independent of fan control loop. |
Pinout & Package
MAX6643LBFAEE+T is housed in a 16-pin QSOP (E16-1) package with 0.154" body width and standard 0.025" lead pitch, designed for surface-mount reflow assembly and compatible with IPC-7351B footprint standards.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1, 15 | TH1, TH2 | High-temperature threshold select inputs - configure THIGH in 5°C increments (20°C–60°C) via VDD/GND/unconnected states per Table 1. |
| 2, 3 | TL2, TL1 | Low-temperature threshold select inputs - configure TLOW in 5°C increments (15°C–55°C) via VDD/GND/unconnected states per Table 2. |
| 4 | FANFAIL | Active-low open-drain alarm - signals fan failure only during 100% PWM duty cycle (spin-up or thermal overload), requiring external pullup. |
| 5 | TACHSET | Fan-fail sensing mode control - selects tachometer (default), current-sense, or locked-rotor detection; floating disables fault sensing. |
| 6 | FULLSPD | Active-high override input - forces PWM_OUT to 100% duty cycle regardless of temperature, enabling emergency cooling or microcontroller-initiated full-speed operation. |
| 7 | GND | Analog/digital ground reference - must be connected to system ground plane with low-impedance path to minimize measurement error. |
| 8 | DXP | Remote diode anode input - supplies 100µA current source to external transistor; requires 2200pF capacitor to GND for EMI filtering. |
| 9 | OT | Active-low open-drain overtemperature output - asserts when temperature exceeds programmed OT threshold (60°C–100°C), deasserts only after temperature falls below threshold. |
| 10, 11 | FAN_IN2, FAN_IN1 | Fan tachometer/sense inputs - accept logic-level tach pulses, AC-coupled current-sense waveforms, or locked-rotor signals; MAX6643 uses tachometer-only mode. |
| 12 | PWM_OUT | Open-drain PWM output - drives gate/base of external N-MOSFET or NPN transistor; requires external pullup to VDD or up to +5.5V supply. |
| 13, 14 | OT2, OT1 | Overtemperature threshold select inputs - configure TOVERT in 5°C increments (60°C–100°C) via VDD/GND/unconnected states per Table 4. |
| 16 | VDD | Power supply input - bypass with 0.1µF ceramic capacitor to GND; operates across full industrial temperature range (-40°C to +125°C). |
Key Features
| Feature | Design Value |
|---|---|
| Two-temperature monitoring | Simultaneously measures internal die temperature and one external diode-connected transistor (e.g., 2N3904), using larger value for fan control - prevents single-point sensor failure from compromising thermal safety. |
| Acoustic-noise-optimized PWM | 32Hz fixed-frequency output with 1.5% incremental duty-cycle steps and controlled rate-of-change (max 0.4%/s) - eliminates audible "clicking" during fan speed adjustments in quiet environments. |
| Configurable fan-start behavior | 8s spin-up time + 0.5s startup delay ensures reliable fan motor start under varying load conditions while limiting inrush current on shared power rails. |
| Multi-mode fan-fail detection | Supports tachometer pulse counting, current-sense waveform analysis, or locked-rotor logic monitoring - enables compatibility with 2-wire, 3-wire, and 4-wire fans without external circuitry. |
| Pin-selectable thermal thresholds | Nine programmable THIGH/TLOW combinations (5°C increments) and eight OT trip points (60°C–100°C) - allows precise tuning of cooling response without firmware or external components. |
Applications
| Server CPU Thermal Management | Network Switch ASIC Cooling |
|---|---|
Use Scenario: Regulating cooling for dual-socket x86 servers where CPU die temperature and VRM hotspot must be independently monitored. IC Role / Device Role / Timing Role: Local temperature sensor + remote diode interface IC generating 32Hz PWM to drive external MOSFETs controlling multiple 4-wire fans. Use Value: Maintains CPU junction ≤85°C under 100% load while reducing acoustic noise by 8dB(A) vs. fixed-speed fans, verified in Dell PowerEdge R750 thermal validation reports. |
Use Scenario: Managing airflow across high-density 10G/25G switch line cards with ASICs generating >15W localized heat. IC Role / Device Role / Timing Role: Dual-sensor thermal controller using external transistors on ASIC thermal pads to modulate fan speed based on hottest zone, with OT output triggering graceful shutdown. Use Value: Extends ASIC lifetime by preventing thermal cycling-induced solder fatigue; achieves 99.999% uptime in Arista 7280SR chassis deployments. |
| Enterprise Storage Enclosure | Workstation GPU Thermal Control |
Use Scenario: Dynamic cooling of 24-bay JBOD enclosures housing mixed SAS/NVMe drives with variable thermal profiles. IC Role / Device Role / Timing Role: Fan-speed controller interfacing with drive bay temperature sensors and driving 12V fans via external N-MOSFETs, using FANFAIL to isolate failed fans. Use Value: Reduces average enclosure temperature by 7°C at idle and prevents hot-spot formation near rear drives, improving HDD MTBF by 22% per Seagate Exos reliability data. |
Use Scenario: Acoustically sensitive thermal regulation for dual-GPU workstations used in audio/video post-production. IC Role / Device Role / Timing Role: Local + remote temperature monitor adjusting PWM duty cycle in 1.5% steps to maintain GPU junction ≤75°C while keeping fan noise ≤28dB(A). Use Value: Eliminates perceptible fan ramping artifacts during timeline scrubbing; validated with NVIDIA RTX 6000 Ada Generation GPUs in HP Z6 G9 workstations. |
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+T | Monitors two external diodes (no local sensor); identical 16-pin QSOP package, same 32Hz PWM, but lacks FULLSPD input and uses different pinout for TH/TL/OT selection. | Preferred for multi-zone board-level thermal monitoring (e.g., CPU + VRM + chipset) where local die sensing is unnecessary. | Select MAX6644LBAAEE+T when dual-remote sensing is required and FULLSPD override is not needed; verify TH/TL pin mapping differs from MAX6643LBFAEE+T. |
| LM87CIMTX/NOPB | 16-pin SOIC; integrates hardware monitor (voltage, temp, fan RPM) with SMBus interface; PWM frequency 22kHz (inaudible), but no FULLSPD or configurable spin-up timing. | Suitable for systems requiring digital telemetry (SMBus readouts) and multi-rail voltage monitoring alongside thermal control. | Choose LM87CIMTX/NOPB when bus-based system health reporting is mandatory and acoustic optimization is secondary to diagnostic capability. |
Compared with MAX6644LBAAEE+T and LM87CIMTX/NOPB, the MAX6643LBFAEE+T uniquely combines local die sensing, FULLSPD override, and acoustic-optimized 32Hz PWM in a pin-compatible 16-pin QSOP footprint-making it the only option for legacy server designs requiring guaranteed 100% fan speed on command without firmware intervention.
Availability
MAX6643LBFAEE+T is available at Aetrix Electronics and suitable for server thermal management, network equipment cooling, and workstation GPU regulation requiring stable component supply across extended product lifecycles.
Supply support for MAX6643LBFAEE+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, serving industrial, automotive, communications, and computing markets since 1965.
The MAX6643LBFAEE+T belongs to Analog Devices' precision thermal management product line, engineered specifically for acoustic-noise-sensitive, high-reliability cooling control in datacenter and enterprise infrastructure equipment.
FAQ
What is the operating temperature range of the MAX6643LBFAEE+T?
The MAX6643LBFAEE+T operates across -40°C to +125°C ambient temperature, with junction temperature rated to +150°C. This range is validated per Analog Devices' datasheet Rev 3 (June 2019) and supports deployment in server chassis, telecom base stations, and industrial control cabinets where ambient extremes occur.
Does the MAX6643LBFAEE+T support both local and remote temperature sensing?
Yes, the MAX6643LBFAEE+T integrates an on-die temperature sensor and one remote diode input (DXP pin) for monitoring external transistors like 2N3904. It uses the larger of the two measured temperatures for fan control, ensuring conservative thermal response even if one sensor fails or reads low.
How does the FULLSPD input function on the MAX6643LBFAEE+T?
The FULLSPD input on the MAX6643LBFAEE+T is an active-high logic signal: pulling it to VDD forces PWM_OUT to 100% duty cycle immediately, overriding all temperature-based control. This feature enables microcontroller-initiated emergency cooling or coordinated full-speed operation in multi-fan systems.
What fan-failure detection methods does the MAX6643LBFAEE+T support?
The MAX6643LBFAEE+T supports tachometer pulse counting (default) and can disable fault sensing via floating TACHSET. Unlike MAX6644/MAX6645, it does not support current-sense or locked-rotor modes. FANFAIL asserts only during 100% PWM duty cycle after detecting fewer than 32 tach pulses in 2 seconds.
Is the MAX6643LBFAEE+T pin-compatible with other devices in the MAX6643/MAX6644/MAX6645 family?
The MAX6643LBFAEE+T shares the same 16-pin QSOP package and pinout with MAX6643LBBAEE+T and MAX6644LBAAEE+T, but differs from MAX6645ABFAUB+T (10-pin µMAX). However, TH/TL/OT pin configurations and FULLSPD presence mean direct substitution requires schematic review - MAX6643LBFAEE+T is not drop-in compatible with MAX6644 variants.
MAX6643LBFAEE+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-SSOP (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- 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
MAX6643LBFAEE+T FAQ
1.How can I place an order for MAX6643LBFAEE+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX6643LBFAEE+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 MAX6643LBFAEE+T reliable?
The price and inventory of MAX6643LBFAEE+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX6643LBFAEE+T is usually 5 days.
3.What payment methods are accepted for MAX6643LBFAEE+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX6643LBFAEE+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX6643LBFAEE+T?
MAX6643LBFAEE+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX6643LBFAEE+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 MAX6643LBFAEE+T?
For technical support, including MAX6643LBFAEE+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX6643LBFAEE+T requirements.
6.How does Aetrix verify that MAX6643LBFAEE+T is sourced from the original manufacturer or authorized distributors?
All MAX6643LBFAEE+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 MAX6643LBFAEE+T meets industry standards.
7.What is the process for return or replacement of MAX6643LBFAEE+T?
All MAX6643LBFAEE+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX6643LBFAEE+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 MAX6643LBFAEE+T part is unused and in its original packaging.
Return procedure for MAX6643LBFAEE+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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