Temperature Monitoring and Fan Control - AMC6821


Temperature Monitoring and Fan Control



The AMC6821 is an intelligent temperature monitor and pulse-width modulation (PWM) fan controller. It is designed for noise-sensitive or power-sensitive applications that require active system cooling. Using either a low-frequency or a high-frequency PWM signal, this device can simultaneously drive a fan, monitor remote sensor diode temperatures, and measure and control the fan speed so that it operates with minimal acoustic noise at the lowest possible speed.

The AMC6821 has three fan control modes: Auto Temperature-Fan mode, Software-RPM mode, and Software-DCY mode. Each mode controls the fan speed by changing the duty cycle of a PWM output. Auto Temperature-Fan mode is an intelligent, closed-loop control that optimizes fan speed according to user-defined parameters. This mode allows the AMC6821 to run as a stand-alone device without CPU intervention; the fan can continue to be controlled (based on temperature measurements) even if the CPU or system locks up. Software-RPM mode is a second closed-loop control. In this mode, the AMC6821 adjusts the PWM output to maintain a consistent fan speed at a user-specified target value; that is, the device functions as a fan speed regulator. Software-RPM mode can also be used to allow the AMC6821 to operate as a stand-alone device. The third mode, Software-DCY, is open-loop. In Software-DCY mode, the PWM duty cycle is set directly by the value written to the device.

The AMC6821 has a programmable SMBALERT output to indicate error conditions and a dedicated FAN-FAULT output to indicate fan failure. The THERM pin is a fail-safe output for over-temperature conditions that can be used to throttle a CPU clock. Additionally, the OVR pin indicates the over-temperature limit as well. All of the alarm thresholds are set through the device registers. The AMC6821 is available in a QSOP-16 package.


  • Remote Temperature Sensor:
    ±2°C Accuracy, 0.125°C Resolution
  • Local Temperature Sensor:
    ±2°C Accuracy, 0.125°C Resolution
  • PWM Controller
  • PWM Frequency: 10Hz to 40kHz
    Duty Cycle: 0% to 100%, 8 Bits
  • Automatic Fan Speed Control Loops
  • SMBus Interface
  • Power: 2.7V to 5.5V
  • Package (Green): QSOP-16 (4mm × 5mm)
  • RoHS Compliant
    • Notebook and Desktop PCs
    • Network Servers
    • Telecommunications Equipment
    • PC-Based Equipment
    • DLP and LCD Projectors

DLP is a trademark of Texas Instruments.
Pentium M, Pentium-IV are trademarks of Intel.
JMC is a trademark of JMC Products.
I2C is a trademark of Philips International, Inc.
All other trademarks are the property of their respective owners.

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Parametrics Compare all products in Monitoring & Fan Control

Analog Inputs
No. of Temperature Sensors
Operating Temperature Range (C)
Temperature Sensor Accuracy (C)
Temperature Sensor Resolution (C)
PWM Duty Cycle Resolution (bits)
Fan Speed Measurement Accuracy (%)
Interface Type
Fan Control Method
Fan Control Output(s)
TruTherm(TM) Beta Compensation
VID Inputs
Fan Speed Inputs
Interrupt Outputs (Count)
Quiescent Current (mA)
Voltage in ADC Resolution (bits)
AMC6821 AMC6821-Q1
1    1   
2    2   
16SSOP    16SSOP   
-40 to 125     
2C max for +50C to +100C
3C max for -40C to +125C   
2C max for +50C to +100C
3C max for -40C to +125C   
0.125    0.125   
8    8   
6    6   
Catalog    Automotive   
SMBus    SMBus   
Linear    Linear   
1 PWM    1 PWM   
No    No   
0    0   
1    1   
1    1   
1.1    1.1   
11    11   

Other qualified versions of AMC6821

Version Part Number Definition
Automotive AMC6821-Q1 Q100 devices qualified for high-reliability automotive applications targeting zero defects