Analog Devices MAX1669 Product Info

• Measures Remote CPU Temperature
• No Calibration Required
• 20Hz to 160Hz PWM Output for Fan
• PWM Frequency Sync Input (260kHz)
• Flexible Fan Interface: Linear or PWM
• SMBus 2-Wire Serial Interface
• Programmable Under/Overtemperature Alarms
• ALERT-bar Latched Interrupt Output
• OVERT-bar Thermostat Output
• Two GPIO Pins
• Write-Once Configuration Protection
• Supports SMBus Alert Response
• ±3°C Temperature Accuracy (-40°C to +125°C, remote)
• 3µA Standby Supply Current
• +3V to +5.5V Supply Range
• Small 16-Pin QSOP Package
• Remote diode sensor, PWM and linear fan control, dual alarms

The MAX1669 fan controller includes a precise digital thermometer that reports the temperature of a remote sensor. The remote sensor is a diode-connected transistor-typically a low-cost, easily mounted 2N3906 PNP type-replacing conventional thermistors or thermocouples. Remote accuracy is ±3°C for transistors from multiple manufacturers, with no calibration needed. The MAX1669 has an independent fan controller with a low-current logic output requiring external power components to interface to a DC brushless fan. The fan controller has two modes of operation: a low-frequency (20Hz to 160Hz) PWM mode intended for driving the fan motor, or a high-impedance DAC output that generates a variable DC control voltage. In PWM mode, the FAN frequency can be synchronized to an external clock.

Other key features include general-purpose inputs/outputs (GPIOs) for fan presence detection and a thermostat output intended as a fan override signal in case the host system loses the ability to communicate. The internal ADC has a wide input voltage range and gives overrange readings when too large an input voltage is applied. Other error-checking includes temperature out-of-range indication and diode open/short faults.

The MAX1669 is available in a space-saving 16-pin QSOP package that allows it to fit adjacent to the SLOT1 connector.

Applications

• Computers: Desktop, Workstation, Server
• Notebook Computers
• Pentium® CPU Cooling
• Servers
• Workstations