Intel C2518 FH8065501516710 Data Sheet

Intel

®

 Atom™ Processor C2000 Product Family for Microserver

September 2014

Datasheet, Vol. 2 of 3

Order Number: 330061-002US

419

This read allows the PECI host to access the minimum, Thermal Design Power (TDP) 

and maximum power settings for the processor package SKU. It also returns the 

maximum time interval or window over which the power can be sustained. If the power 

limiting entity specifies a power limit value outside of the range specified through these 

settings, power regulation cannot be guaranteed. Since this data is 64 bits wide, PECI 

facilitates access to this register by allowing two requests to read the lower 32 bits and 

upper 32 bits separately as shown in 

. Power units for this 

read are determined as per the Package Power SKU Unit settings described in 

.

The Package Power SKU data is programmed by the SoC internal Power Controller Unit 

(PCU) firmware during boot time based on SKU dependent power-on default values set 

during SoC manufacturing. The TDP Package Power specified through bits [14:0] in 

 is the maximum value of the Power Limit1 field described in 

 while the Maximum Package Power in bits [46:32] is the maximum value of 

the Power Limit2 field which is also described in 

.

The Minimum Package Power in bits [30:16] is applicable to both the Power Limit1 and 

Power Limit2 fields and corresponds to a mode when all the cores are operational and 

in their lowest frequency mode. Attempts to program the power limit below the 

minimum power value may not be effective since BIOS/OS, and not the integrated PCU, 

controls disabling of cores and core activity.

Maximum Time Window’ in bits [54:48] is representative of the maximum rate at which 

the internal PCU can sample the package energy consumption and reactively take the 

necessary measures to meet the imposed power limits. Programming too-large of a 

time window runs the risk of the PCU not being able to monitor and take timely action 

on package energy excursions. On the other hand, programming too-small of a time 

window may not give the PCU enough time to sample energy information and enforce 

the limit. The minimum value of the ‘time window’ can be obtained by reading bits 

[21:15] of the PWR_LIMIT_MISC_INFO CSR using the PECI RdPCIConfigLocal() 

command.

TDP Package Power

0

31

Minimum Package Power

16

30

14

15

Maximum Package Power

32

63

Maximum Time 

Window

48

55

46

47

54