Intel Pentium 4 Processor CK00 Clock Synthesizer/Driver Design Guidelines

CK00 Clock Synthesizer/Driver Design Guidelines
Page 38
Table 6.4 CKx_RGR Pin Description Table
Pin Type Qty Symbol Description
48,1 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.
45 Output 1 3VMref 3V reference to memory clock driver
44 Output 1 3Vmref_b 3V reference to memory clock driver (out of phase with
3VMref)
42 Input 1 Spread# Invokes Spread Spectrum functionality on the
Differential Host clocks, MRef/MRef_b clocks, 66MHz
clocks, and 33MHz PCI clocks. Active Low.
41,40 Buffer X1 1 Host/Host_bar Host pair 1
38,37 Buffer X1 1 Host/Host_bar Host pair 2
35 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.
32 Input 1 PWRDWN# Invokes power-down mode. Active Low.
30,29,27 3.3V output 3 3V66 66MHz 3.3V outputs
24,23 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.
21 Input 1 SEL100/133 Host Frequency Select. Low=100MHz, High=133MHz
19,18,16,15,13,12,10,
9,7,6,
3.3V output 10 PCI 3.3V 33MHz outputs
4 Xtal output 1 Xtal_out 14.318MHz Crystal output
3 Xtal input 1 Xtal_in 14.318MHz Crystal input
46,43 Power/Gnd 3.3M, GndM Power and ground pins recommended for 3VMref and
3VMref_b dedicated use
39,36 Power/Gnd 3.3H, GndH Power and ground pins recommended for
Host/Host_bar dedicated use
34,33 Power/Gnd 3.3Core,
GndCore
Power and ground pins recommended for dedicated
core use
31,28,26 Power/Gnd 3.3L,GndL Power and ground pins recommended for 3V66
dedicated use
25,22 Power/Gnd 3.3U, GndU Power and ground pins recommended for 48MHz
dedicated use
20,17,14,11,8,5 Power/Gnd 3.3P,GndP Power and ground pins recommended for PCI
dedicated use
2,48 Power/Gnd 3.3R,GndR Power and ground pins recommended for REF clock
and Xtal dedicated use