Intel E1400 Design Guidelines - Page 117

Legacy Fan Speed Control Figure 7-44. FSC Definition Example Requirements Classification Required - an essential part of the design necessary to meet specifications. Should be considered a pass or fail in selection of a board. Suggested - highly desired for consistency among designs. May be specified or expanded by the system integrator. The motherboard needs to have a fan speed control component that has the following characteristics: PWM output programmable to 21-28 kHz (required). PWM output set to 25 kHz (Suggested) as this value is the design target for the reference and for the Boxed Processor. External/remote thermal sensor measurement capability (required). Must support PECI and thermal diode using a SST device External/remote thermal sensor sampling rate 4 times per second (required). External/remote diode measurement (SST device) is calibrated by the component vendor to account for the diode ideality and package series resistance as listed in the appropriate datasheet. (Suggested). Note: If the SST thermal sensor is not calibrated with the diode ideality and package series resistance, verify the board manufacturer has made provisions within the BIOS setup or other utility to input the corrections factors. The BIOS, at a minimum, must program the settings in Table 7-4 or Table 7-5, as appropriate, into the fan speed controller. The values are the minimum required to establish a fan speed control algorithm consistent with this document, the reference thermal solution and Boxed Processor thermal solution. Thermal and Mechanical Design Guidelines 117