Vrefsys Pin; Zn And Zp Pins - AMD ATHLON 8 Datasheet

AMD Athlon™ XP Processor Model 8 Data Sheet

VREFSYS Pin

ZN and ZP Pins

80
Preliminary Information
Table 28. VID[4:0] Code to Voltage Definition
V
VID[4:0]
CC_CORE
00000 1.850
00001 1.825
00010 1.800
00011 1.775
00100 1.750
00101 1.725
00111 1.675
01000 1.650
01001 1.625
01010 1.600
01011 1.575
01100 1.550
01101 1.525
01110 1.500
01111 1.475
For more information, see the "Required Circuits" chapter of
the AMD Athlon™ Processor-Based Motherboard Design Guide,
order# 24363.
VREFSYS (W5) drives the threshold voltage for the system bus
input receivers. The value of VREFSYS is system specific. In
addition, to minimize V
include decoupling capacitors. For more information, see the
AMD Athlon™ Processor-Based Motherboard Design Guide, order#
24363.
ZN (AC5) and ZP (AE5) are the push-pull compensation circuit
pins. In Push-Pull mode (selected by the SIP parameter
SysPushPull asserted), ZN is tied to V
that has a resistance matching the impedance Z
transmission line. ZP is tied to VSS with a resistor that has a
resistance matching the impedance Z
Pin Descriptions
(V) V
VID[4:0]
10000
10001
10010
10011
10100
10101
10111
11000
11001
11010
11011
11100
11101
11110
11111
noise rejection from VREFSYS,
CC_CORE
of the transmission line.
0
25175H—March 2003
(V)
CC_CORE
1.450
1.425
1.400
1.375
1.350
1.325
1.275
1.250
1.225
1.200
1.175
1.150
1.125
1.100
No CPU
with a resistor
CC_CORE
of the
0
Chapter 11