W83627DHG Datasheet, PDF (49/268 Pages) Winbond – WINBOND LPC I/O

W83627DHG
5. Since the PECI temperature is a relative value, the W83627DHG provides registers for each PECI
Agent to convert the relative value to a more traditional “absolute” format. The TBase registers (Logical
Device C, CR[E1h]~CR[E4h]) store the “base” temperature. By means of BIOS/software, the desired
base temperature can be written to these registers. Important: the value must be positive. Otherwise
abnormal temperature responses will take place. Here is an example on how to obtain TBase value:
(1). Use a digital thermometer on the surface of the PECI processor to measure the processor body
temperature.
(2). Power up the system the PECI processor. Run the processor to 100% loading.
(3). After the system is stable, read the PECI reading from Logical Device C, CR[FEh] and CR[FFh] and
record the value of digital thermometer.
(4). Calculate TBase. For example, if PECI = -10 and the digital thermometer is 50’C, then TBase could
be set to 60’C. ( 60 – 10 = 50 ).
6. There are two temperature reading registers in the W83627DHG: CPUTIN (Bank1 Index 50h & 51h)
and AUXTIN (Bank2 Index 50h & 51h). The source of the CPUTIN value is determined by the value
programmed into the CPUFANOUT0 monitor Temperature source select register (Hardware Monitor
Device, Bank 0, Index 49h, bits (2..0)). The source of AUXTIN value is determined by the value
programmed into the AUXFANOUT monitor Temperature source select register (Hardware Monitor
Device, Bank 0, Index 49h, bits(6..4))
7. The temperature values in CPUTIN and AUXTIN are:
CPUTIN = (TBase) + (PECI Agent relative temperature)
AUXTIN = (TBase) + (PECI Agent relative temperature)
Example:
If the PECI relative temperature of agent 1 is -10; TBase is set to 72°C, and Bank0 Index 49h
selects PECI Agent 1 as the temperature source, the reported temperature will be 62°C (-10 + 72).
Please be noted that when the temperature source is selected as PECI, the CPUTIN or AUXTIN
register reading does not reflect the actual temperature of processor.
8. In addition, the W83627DHG provides a PECISB pin that can be connected to a PECI host (e.g.
chipset), so the W83627DHG becomes a bridge between that PECI host and the PECI client (e.g. CPU
with PECI function). The bridge can pass the CPU PECI signals by programming Configure Register at
Logical Device C, CR[E5h] Bit 0. An illustration is provided below (ICH8 is the alternative PECI host).
Publication Release Date: Aug, 22, 2007
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Version 1.4