MAX6643

PRODUCTION

Automatic PWM Fan-Speed Controllers with Overtemperature Output

Automatic PWM Fan-Speed Controllers with Overtemperature Output Eliminate Software Overhead

Data Sheet (Rev. 3) Product Selection Table

Part Models: 4
1ku List Price: Starting From $1.71

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Overview

Simple, Automatic Fan-Speed Control
Internal and External Temperature Sensing
Detect Fan Failure Through Locked-Rotor Output, Tachometer Output, or Fan-Supply Current Sensing
Multiple, 1.6% Output Duty-Cycle Steps for Low Audibility of Fan-Speed Changes
Pin-Selectable or Factory-Selectable Low-Temperature Fan Threshold
Pin-Selectable or Factory-Selectable High-Temperature Fan Threshold
Spin-Up Time Ensures Fan Start
Fan-Start Delay Minimizes Power-Supply Load at Power-Up
32Hz PWM Output
Controlled Duty-Cycle Rate-of-Change Ensures Good Acoustic Performance
2°C Temperature-Measurement Accuracy
FULLSPD/FULLSPD Input Sets PWM to 100%
Pin-Selectable Active-Low OT Output Threshold
16-Pin QSOP and 10-Pin µMAX Packages

The MAX6643/MAX6644/MAX6645 monitor temperature and automatically adjust fan speed to ensure optimum cooling while minimizing acoustic noise from the fan. Each device measures two temperature locations.

The MAX6643/MAX6644/MAX6645 generate a PWM waveform that drives an external power transistor, which in turn modulates the fan's power supply. The MAX6643/MAX6644/MAX6645 monitor temperature and adjust the duty cycle of the PWM output waveform to control the fan's speed according to the cooling needs of the system. The MAX6643 monitors its own die temperature and an optional external transistor's temperature, while the MAX6644 and MAX6645 each monitor the temperatures of one or two external diode-connected transistors.

The MAX6643 and MAX6644 have nine selectable trip temperatures (in 5°C increments). The MAX6645 is factory programmed and is not pin selectable.

All versions include an overtemperature output (active-low OT). Active-low OT can be used for warning or system shutdown. The MAX6643 also features a FULLSPD input that forces the PWM duty cycle to 100%. The MAX6643/MAX6644/MAX6645 also feature a active-low FANFAIL output that indicates a failed fan. See the Selector Guide in the full data sheet for a complete list of each device's functions.

The MAX6643 and MAX6644 are available in a small 16-pin QSOP package and the MAX6645 is available in a 10-pin µMAX^® package. All versions operate from 3.0V to 5.5V supply voltages and consume 500µA (typ) supply current.

Applications

Desktop Computers
Networking Equipment
Servers
Storage Equipment
Workstations

Part Models: 4
1ku List Price: Starting From $1.71

Documentation

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal. View our quality and reliability program and certifications for more information.

Part Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
MAX6643LBBAEE+	16-QSOP-150_MIL	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
MAX6643LBBAEE+T	16-QSOP-150_MIL	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
MAX6643LBFAEE+	16-QSOP-150_MIL	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
MAX6643LBFAEE+T	16-QSOP-150_MIL	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

Jan 24, 2019 - 1746N ASSEMBLY
		pcn_1746n
MAX6643LBFAEE+	PRODUCTION	pcn_1746n

This is the most up-to-date revision of the Data Sheet.

Software Resources

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Hardware Ecosystem

Parts	Product Life Cycle	Description
Fan Speed & Thermoelectric Cooler (TEC) Controllers 2
MAX6650	PRODUCTION	Fan-Speed Regulators and Monitors with SMBus/I²C-Compatible Interface
MAX6660	PRODUCTION	Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface
Temperature Sensors 1
MAX6668		Remote Temperature Switches with Integrated Fan Controller/Driver

Evaluation Kits

Evaluation Kit for the MAX6643/MAX6644

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Features and Benefits

Automatic Fan-Speed Control
Local and Remote Temperature Sensing
Programmable Low, High, and Over-Temperature Thresholds
Minimizes Acoustic Noise
Fan-Failure Detection
Configured for 5V to 12V Fans Up to 1A
Reconfigurable for Up to Two Fans
Surface-Mount Components
Fully Assembled and Tested
Evaluates All Versions of the MAX6643 and MAX6644 (IC Replacement Required)

Product Details

The MAX6643LB evaluation kit (EV kit) is a fully assembled and tested surface-mount circuit board that demonstrates the operation of the MAX6643LB fan controller. The MAX6643LB monitors its internal temperature and the junction temperature of an optional external diode-connected transistor. Based on the temperature measurements, the MAX6643LB generates a PWM waveform that drives the gate of an external n-channel power MOSFET, which modulates the cooling fan's power supply, thus providing automatic fan-speed control.

The high- and low-temperature fan-control thresholds are easily programmable by connecting programming pins to ground or supply or leaving them disconnected. The fan-control algorithm is optimized to minimize the audible artifacts of varying fan speeds. Fan failure is detected by monitoring the fan's tachometer output. Also provided is an over-temperature output with pin-programmable threshold.

The EV kit can also be used to evaluate other versions of the MAX6643/MAX6644 fan-controlling ICs.

Applications

Desktop Computers
Networking Equipment
Servers
Storage Equipment
Workstations

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Overview

Documentation

Data Sheet 1

Design Note 2

Technical Articles 1