SBAS475A June 2009 – January 2023 AMC6821-Q1
PRODUCTION DATA
The AMC6821-Q1 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-Q1 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-Q1 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-Q1 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-Q1 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-Q1 is available in a SSOP-16 package.