
2
Integrated
Circuit
Systems, Inc.
ICS952906A
1236A—08/06/07
Pin Description
PIN # PIN NAME
PIN TYPE
DESCRIPTION
1
*FS1/REF0
I/O
Frequency select latch input pin / 14.318 MHz reference clock.
2
**FS0/REF1
I/O
Frequency select latch input pin / 14.318 MHz reference clock.
3
VDDREF
PWR
Ref, XTAL power supply, nominal 3.3V
4
X1
IN
Crystal input, Nominally 14.318MHz.
5
X2
OUT
Crystal output, Nominally 14.318MHz
6
GND
PWR
Ground pin.
7
**FS2/PCICLK_F0
I/O
Frequency select latch input pin / 3.3V PCI free running clock output.
8
**FS4/PCICLK_F1
I/O
Frequency select latch input pin / 3.3V PCI free running clock output.
9
PCICLK_F2
OUT
Free running PCI clock not affected by PCI_STOP# .
10
VDDPCI
PWR
Power supply for PCI clocks, nominal 3.3V
11
GND
PWR
Ground pin.
12
**MODE/PCICLK0
I/O
Function select latch input pin, 0=Desktop Mode (pin 44/45 are outputs), 1=Mobile Mode (pin44/45 are STOP
inputs) / PCI clock output.
13
PCICLK1
OUT
PCI clock output.
14
PCICLK2
OUT
PCI clock output.
15
PCICLK3
OUT
PCI clock output.
16
PCICLK4
OUT
PCI clock output.
17
VDDPCI
PWR
Power supply for PCI clocks, nominal 3.3V
18
GND
PWR
Ground pin.
19
PCICLK5
OUT
PCI clock output.
20
PCICLK6
OUT
PCI clock output.
21
**FS3/48MHz
I/O
Frequency select latch input pin / Fixed 48MHz clock output. 3.3V
22
**Sel24_48#/24_48MHz
I/O
Latched select input for 24/48MHz output / 24/48MHz clock output. 1=24MHz, 0 = 48MHz.
23
GND
PWR
Ground pin.
24
VDD48
PWR
Power pin for the 48MHz output.3.3V
25
3V66_2
OUT
3.3V 66.66MHz clock output
26
3V66_1
OUT
3.3V 66.66MHz clock output
27
VDD3V66
PWR
Power pin for the 3.3V 66MHz clocks.
28
GND
PWR
Ground pin.
29
3V66_0
OUT
3.3V 66.66MHz clock output
30
Reset#
OUT
Real time system reset signal for frequency gear ratio change or watchdog timer timeout. This signal is
active low.
31
SCLK
IN
Clock pin of SMBus circuitry, 5V tolerant.
32
SDATA
I/O
Data pin for SMBus circuitry, 3.3V tolerant.
33
VttPWR_GD/PD#
IN
This 3.3V LVTTL input is a level sensitive strobe used to determine when latch inputs are valid and are ready
to be sampled. This is an active high input. / Asynchronous active low input pin used to power down the
device into a low power state.
34
VDD2.5
PWR
Power supply, nominal 2.5V
35
25Mhz_1
OUT
25MHz clock output, 2.5V
36
25Mhz_0
OUT
25MHz clock output, 2.5V
37
GND
PWR
Ground pin.
38
CPUCLKC0
OUT
Complementary clock of differential pair CPU outputs. These are current mode outputs. External resistors
are required for voltage bias.
39
CPUCLKT0
OUT
True clock of differential pair CPU outputs. These are current mode outputs. External resistors are required
for voltage bias.
40
VDDCPU
PWR
Supply for CPU clocks, 3.3V nominal
41
CPUCLKC1
OUT
Complementary clock of differential pair CPU outputs. These are current mode outputs. External resistors
are required for voltage bias.
42
CPUCLKT1
OUT
True clock of differential pair CPU outputs. These are current mode outputs. External resistors are required
for voltage bias.
43
GND
PWR
Ground pin.
44
CPUCLKC_ITP/(CPU_STOP#) I/O
Complementary clock of differential pair CPU outputs. These are current mode outputs. External resistors
are required for voltage bias. / Stops all CPUCLK besides the free running clocks
45
CPUCLKT_ITP/(PCI_STOP#)
I/O
True clock of differential pair CPU outputs. These are current mode outputs. External resistors are required
for voltage bias. / Stops all PCICLK besides the free running clocks
46
IREF
OUT
This pin establishes the reference current for the differential current-mode output pairs. This pin requires a
fixed precision resistor tied to ground in order to establish the appropriate current. 475 ohms is the standard
value.
47
GND
PWR
Ground pin.
48
VDDA
PWR
3.3V power for the PLL core.