DESCRIPTION
Support for Platform Environmental Control Interface (PECI) is included. Using temperature information from these four zones, an automatic fan speed control algorithm is employed to minimize acoustic impact while achieving recommended CPU temperature under varying operational loads. To set fan speed, the aSC7621 has three independent pulse width modulation (PWM) outputs that are controlled by one, or a combination of three, temperature zones. Both high- and low-frequency PWM ranges are supported. The aSC7621 also includes a digital filter that can be invoked to smooth temperature readings for better control of fan speed and minimum acoustic impact. The aSC7621 has tachometer inputs to measure fan speed on up to four fans. Limit and status registers for all measured values are included to alert the system host that any measurements are outside of programmed limits via status registers. System voltages of VCCP, 2.5V, 3.3V, 5.0V, and 12V motherboard power are monitored efficiently with internal scaling resistors.
