ICS950220 Datasheet, PDF (11/20 Pages) Integrated Circuit Systems – Programmable Timing Control Hub™ for P4™

Integrated
Circuit
Systems, Inc.
ICS950220
Byte 20: Group Skew Control Register
Bit
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Name
PCI_Skew 3
PCI_Skew 2
PCI_Skew 1
PCI_Skew 0
PCI_Skew 3
PCI_Skew 2
PCI_Skew 1
PCI_Skew 0
PWD
1
0
0
0
1
0
0
0
Description
These 4 bits can change the CPU to PCI (6:0) skew from -0.3ns
1.2ns. Default at power up is 0.5ns. Each binary increment or
decrement of Bits (3:0) will increase or decrease the delay of the
PCI clocks by 100ps.
These 4 bits can change the CPU to PCI (8:7) skew from -0.6ns
1.2ns. Default at power up is 0.4ns. Each binary increment or
decrement of Bit (3:0) will increase or decrease the delay of the
PCI clocks by 100ps.
Byte 21: Slew Rate Control Register
Bit
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Name
Reserved
Reserved
PCIF Slew 1
PCIF Slew 0
3V66 (3:1)_Slew 1
3V66 (3:1)_Slew 1
3V66_0_Slew 1
3V66_0_Slew 0
PWD
1
0
1
0
1
0
1
0
Description
Reserved
Reserved
PCIF(1:0) clock slew rate control bits.
01 = strong: 11 = normal; 10 = weak
3V66 (3:1) clock slew rate control bits.
01 = strong: 11 = normal; 10 = weak
3V66_0 clock slew rate control bits.
01 = strong: 11 = normal; 10 = weak
Byte 22: Slew Rate Control Register
Bit
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Name
REF Slew 1
REF Slew 0
PCI (6:4) Slew 1
PCI (6:4) Slew 0
PCI (3:1) Slew 1
PCI (3:1) Slew 0
PCI0 Slew 1
PCI0 Slew 0
PWD
1
0
1
0
1
0
1
0
Description
REF clock slew rate control bits.
01 = strong: 11 = normal; 10 = weak
PCI (6:4) clock slew rate control bits.
01 = strong: 11 = normal; 10 = weak
PCI (3:1) clock slew rate control bits.
01 = strong: 11 = normal; 10 = weak
PCI0 clock slew rate control bits.
01 = strong: 11 = normal; 10 = weak
Byte 23: Slew Rate Control Register
Bit
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Name
Reserved
Reserved
VCH Slew 1
VCH Slew 0
48USB Slew 1
48USB Slew 0
48DOT Slew 1
48DOT Slew 0
PWD
X
X
1
0
1
0
1
0
Description
Reserved
VCH clock slew rate control bits.
01 = strong: 11 = normal; 10 = weakk
48USB clock slew rate control bits.
01 = strong: 11 = normal; 10 = weakk
48DOT clock slew rate control bits.
01 = strong: 11 = normal; 10 = weak
0467F—07/28/05
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