CY28405
Pin Description
Pin No.
Name
Type
O, SE
I
Description
1, 2
REF(0:1)
Reference Clock. 3.3V 14.318-MHz clock output.
1, 2, 7, 8, 9 FS_A, FS_B, FS_C,
FS_D, FS_E
3.3V LVTTL latched input for CPU frequency selection.
4
XIN
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.
39, 42, 45 CPUT(0:1,ITP)
38, 41, 44 CPUC(0:1,ITP)
O, DIF CPU Clock Output. Differential CPU clock outputs.
O, DIF CPU Clock Output. Differential CPU clock outputs.
Do Not Connect.
36, 35
30, 29
DNC
3V66(0:1)
O, SE
66-MHz Clock Output. 3.3V 66-MHz clock from internal VCO.
25
3V66_3/VCH/SELVCH
I/O, SE 48- or 66-MHz Clock Output. 3.3V selectable through external SELVCH
strapping resistor and SMBus to be 66-MHz or 48-MHz. Default is 66-MHz.
0 = 66 MHz, 1 = 48 MHz
PD
26
3V66_2/MODE
I/O, SE 66-MHz Clock Output. 3.3V 66-MHz clock from internal VCO. Reset or
PU
Power-down Mode Select. Selects between RESET# output or PWRDWN#
input for the PWRDWN#/RESET# pin. Default is RESET#. 0 = PD#, 1 =
RESET
7, 8, 9
PCIF(0:2)
O, SE
O, SE
Free Running PCI Output. 33-MHz clocks divided down from 3V66.
PCI Clock Output. 33-MHz clocks divided down from 3V66.
12, 13, 14, PCI(0:5)
15, 18, 19
22
21
46
USB_48
DOT_48
IREF
O, SE
O, SE
I
Fixed 48-MHz clock output.
Fixed 48-MHz clock output.
Current Reference. A precision resistor is attached to this pin which is
connected to the internal current reference.
20
33
RESET#/PD#
I/O, PU 3.3V LVTTL input for Power-down# active LOW. Watchdog Timeout
Reset Output
VTT_PWRGD#
I
3.3V LVTTL input is a level sensitive strobe used to latch the FS[A:E]
input (active LOW).
32
31
48
47
SDATA
SCLK
VDDA
VSSA
I/O
I
SMBus compatible SDATA.
SMBus compatible SCLOCK.
3.3V Power supply for PLL.
Ground for PLL.
PWR
GND
PWR
3, 10, 16, VDD(REF,PCI,48,3V66,C
24, 27, 34, PU,ITP)
40
3.3V Power supply for outputs.
6, 11, 17, VSS(REF,PCI,48,3V66,
23, 28, 37, CPU,ITP)
43
GND
Ground for outputs.
Rev 1.0,November 20, 2006
Page 2 of 18
SPECTRALINEAR [ SPECTRALINEAR INC ]
