CY28409
Pin Description
Pin No.
Name
REF(0:1)
XIN
Type
Description
1, 2
4
O, SE Reference Clock. 3.3V 14.318-MHz clock output.
I
Crystal Connection or External Reference Frequency Input. This pin has dual
functions. It can be used as an external 14.318-MHz crystal connection or as an external
reference frequency input.
5
XOUT
O, SE Crystal Connection. Connection for an external 14.318-MHz crystal output.
41,44,47
CPUT(0:2)
O, DIF CPU Clock Output. Differential CPU clock outputs. See Table 1 for frequency config-
uration.
40,43,46
CPUC(0:2)
O, DIF CPU Clock Output. Differential CPU clock outputs. See Table 1 for frequency config-
uration.
38, 37
SRCT, SRCC
O, DIF Differential serial reference clock.
22,23,26,27 3V66(0:3)
O, SE 66-MHz Clock Output. 3.3V 66-MHz clock from internal VCO.
O, SE 48-/66-MHz Clock Output. 3.3V selectable through SMBus to be 66 or 48 MHz.
O, SE Free-running PCI Output. 33-MHz clocks divided down from 3V66.
O, SE PCI Clock Output. 33-MHz clocks divided down from 3V66.
29
3V66_4VCH
PCIF(0:2)
PCI(0:6)
7,8,9
12,13,14,
15,18,19,20
31,
32
USB_48
DOT_48
FS_A, FS_B
IREF
O, SE Fixed 48-MHz clock output.
O, SE Fixed 48-MHz clock output.
51,56
52
I
I
3.3V LVTTL input for CPU frequency selection.
Current Reference. A precision resistor is attached to this pin which is connected to
the internal current reference.
21
50
49
35
PD#
I, PU 3.3V LVTTL input for Power-Down# active LOW.
I, PU 3.3V LVTTL input for CPU_STP# active LOW.
I, PU 3.3V LVTTL input for PCI_STP# active LOW.
CPU_STP#
PCI_STP#
VTT_PWRGD#
I
3.3V LVTTL input is a level sensitive strobe used to latch the FS_A and FS_B
inputs (active LOW).
30
SDATA
I/O
I
SMBus-compatible SDATA.
SMBus-compatible SCLOCK.
28
SCLK
53
VSS_IREF
VDD_A
GND Ground for current reference.
PWR 3.3V power supply for PLL.
GND Ground for PLL.
55
54
VSS_A
42,48
45
VDD_CPU
VSS_CPU
VDD_SRC
VSS_SRC
VDD_48
PWR 3.3V power supply for outputs.
GND Ground for outputs.
36
PWR 3.3V power supply for outputs.
GND Ground for outputs.
39
34
PWR 3.3V power supply for outputs.
GND Ground for outputs.
33
VSS_48
10,16
11,17
24
VDD_PCI
VSS_PCI
VDD_3V66
VSS_3V66
VDD_REF
VSS_REF
PWR 3.3V power supply for outputs.
GND Ground for outputs.
PWR 3.3V power supply for outputs.
GND Ground for outputs.
25
3
PWR 3.3V power supply for outputs.
GND Ground for outputs.
6
Rev 1.0,November 22, 2006
Page 2 of 16
SPECTRALINEAR [ SPECTRALINEAR INC ]
