Intel Pentium 4 Processor CK00 Clock Synthesizer/Driver Design Guidelines

CK00 Clock Synthesizer/Driver Design Guidelines
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Table 6.1 CKx_SKS Pin Description Table
Pin Type Qty Symbol Description
55 3.3V output 1 3VMref 3V reference to memory clock driver
54 3.3V output 1 3VMRef_b 3V reference to memory clock driver (out of phase with
3Vmref)
52 Input 1 Spread# Invokes Spread Spectrum functionality on the Differential
Host clocks, MRef/MRef_b clocks, 66MHz clocks, and
33MHz PCI clocks. Active Low.
51,50 Buffer X1 Host/Host_b Host pair 1
48,47 Buffer X1 Host/Host_b Host pair 2
45, 44 Buffer X1 Host/Host_b Host pair 3
42, 41 Buffer X1 Host/Host_b Host pair 4
39 Special 1 I_Ref This pin establishes the reference current for the Host
pairs. This pin takes a fixed precision resistor tied to
ground in order to establish the appropriate current.
35,34,31,30 3.3V output 4 3V66 66MHz 3.3V outputs
28 Input 1 PWRDWN# Invokes power-down mode. Active Low.
26,25 Output and
Latched Input
2 48MHz/SelA,
48MHz/SelB
SelA and SelB inputs are sensed on power-up and then
internally latched prior to the pin being used for output of
3V 48MHz clocks.
23 Input 1 SEL100/133 Host Frequency Select. Low=100MHz, High=133MHz
21,20,18,17,
15,14,12,11,
9,8
3.3V output 10 PCI 3.3V 33MHz outputs
6 Xtal output 1 Xtal_out 14.318MHz Crystal output
5 Xtal input 1 Xtal_in 14.318MHz Crystal input
3,2 Output and
Latched Input
2 Ref/MultSel0
Ref/MultSel1
MultSel0 and MultSel1 inputs are sensed on power-up and
then internally latched prior to the pin being used for output
of 3V 14.318MHz clocks.
56, 53 Power/Gnd 3.3M, GndM Power and ground pins recommended for 3VMref and
3VMref_b dedicated use
49,46,43,40 Power/Gnd 3.3H, GndH Power and ground pins recommended for Host/Host_bar
dedicated use
38,37 Power/Gnd 3.3Core,
GndCore
Power and ground pins recommended for dedicated core
use
36,33,32,29 Power/Gnd 3.3L,GndL Power and ground pins recommended for 3V66 dedicated
use
27,24 Power/Gnd 3.3U, GndU Power and ground pins recommended for 48MHz
dedicated use
22,19,16,13,
10,7
Power/Gnd 3.3P,GndP Power and ground pins recommended for PCI dedicated
use
4,1 Power/Gnd 3.3R,GndR Power and ground pins recommended for REF clock and
Xtal dedicated use