Specifications

Intel
®
810E2 Chipset Platform
R
38 Design Guide
2.2.11. Thermal/EMI Differences
Heatsink requirements will be different for FC-PGA processors from previous processors using PPGA
packaging. The current flexible motherboard guidelines for Pentium III (FC-PGA w/256-K L2 cache)
processors calls for 28.4 W.
• Increased power density for Pentium III processor (approximately 27 W/cm
2
).
• Different thermal design verification for FC-PGA compared to PPGA packaged processors. Pentium
III processors are specified using Tjunction versus Tcase (used with Celeron processors).
• New heatsink for FC-PGA package which is not backwards compatible with PPGA processors.
• New heatsink clips for FC-PGA processor heatsinks.
2.2.12. Debug Port Changes
Due to the lower voltage technology employed with the Pentium III processor, changes are required to
support the debug port. Previously, the test access port (TAP) signals used 2.5V logic. This is the case
with the Celeron processor in the PPGA package. Pentium III utilizes 1.5V logic levels on the TAP. As a
result, a new ITP connector is to be used on flexible PGA370 designs. The new 1.5V connector is the
mirror image of the older 2.5V connector. Either connector will fit into the same printed circuit board
layout. Just the pin numbers would change, as can be seen in the drawing below.
Figure 8. TAP Connector Comparison
1 3 5 7 9 13 15 17
12 14 16 18 20
21 23 25 27 29
24 26 28 30
11 19
2 4 6 8 10 22
1 3 5 7 9 13 15 17
12 14 16 18 20
21 23 25 27 29
24 26 28 30
11 19
2 4 6 8 10 22
2.5V connector, AMP 104068-3 Vertical Plug, Top View
1.5V connector, AMP 104078-4 Vertical Receptacle, Top View
RESET#
RESET#
Caution: The Pentium III processor requires an in-target probe (ITP) with a 1.5V tolerant buffer. Previous ITPs are
designed to work with higher voltages and may damage the processor if they are connected to an
Pentium III processor.