Peci Specifications; Temperature Data Format Comparison: Thermal Diode Vs. Peci Digital Thermal Sensor - Intel 5148LV - Xeon Dual Core Active H Datasheet

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Figure 6-8.

Temperature Data Format Comparison: Thermal Diode vs. PECI Digital

Thermal Sensor

6.3.1.2

Processor Thermal Data Sample Rate and Filtering

The DTS provides an improved capability to monitor device hot spots, which inherently

leads to more varying temperature readings over short time intervals. The DTS sample

interval range can be modified, and a data filtering algorithm can be activated to help

moderate this. The DTS sample interval range is 82 µs (default) to 20 ms (max). This

value can be set in BIOS.

To reduce the sample rate requirements on PECI and improve thermal data stability vs.

time the processor DTS also implements an averaging algorithm that filters the

incoming data. This is an alpha-beta filter with coefficients of 0.5, and is expressed

mathematically as: Current_filtered_temp = (Previous_filtered_temp / 2) +

(new_sensor_temp / 2). This filtering algorithm is fixed and cannot be changed. It is

on by default and can be turned off in BIOS.

Host controllers should utilize the min/max sample times to determine the appropriate

sample rate based on the controller's fan control algorithm and targeted response rate.

The key items to take into account when settling on a fan control algorithm are the DTS

sample rate, whether the temperature filter is enabled, how often the PECI host will

poll the processor for temperature data, and the rate at which fan speed is changed.

Depending on the designer's specific requirements the DTS sample rate and alpha-beta

filter may have no effect on the fan control algorithm.

6.3.2