W48C101-01 Datasheet, PDF (2/8 Pages) Cypress Semiconductor – Spread Spectrum BX System Frequency Generator

PRELIMINARY
W48C101-01
Pin Definitions
Pin
Pin Name
No.
CPU0:3
40, 39, 36,
35
PCI1:7
8, 10, 11, 13,
14, 16, 17
PCI_F
7
CPU_STOP#
30
PCI_STOP#
31
SPREAD#
APIC0:1
48MHz
REF0:2
SEL100/66#
SEL1:0
X1
X2
PWR_DWN#
28
45, 44
22, 23
1, 2, 47
25, 26, 27
4
5
29
VDDQ3
VDDQ2
GND
NC
9, 15, 19, 21,
33, 48
37,41,46
3, 6, 12, 18,
20, 24, 32,
34, 38, 43
42
Pin
Type
O
O
O
I
I
I
O
O
O
I
I
I
I
P
P
G
-
Pin Description
CPU Clock Outputs 0 through 3: These four CPU clock outputs are controlled by
the CPU_STOP# control pin. Output voltage swing is controlled by voltage applied
to VDDQ2.
PCI Bus Clock Outputs 1 through 7: These seven PCI clock outputs are controlled
by the PCI_STOP# control pin. Output voltage swing is controlled by voltage applied
to VDDQ3.
Fixed PCI Clock Output: Unlike PCI1:7 outputs, this output is not controlled by the
PCI_STOP# control pin. Output voltage swing is controlled by voltage applied to
VDDQ3.
CPU_STOP# Input: When brought LOW, clock outputs CPU0:3 are stopped LOW
after completing a full clock cycle (2–3 CPU clock latency). When brought HIGH,
clock outputs CPU0:3 start beginning with a full clock cycle (2–3 CPU clock latency).
PCI_STOP# Input: The PCI_STOP# input enables the PCI 1:7 outputs when HIGH
and causes them to remain at logic 0 when LOW. The PCI_STOP signal is latched
on the rising edge of PCI_F. Its effects take place on the next PCI_F clock cycle.
SPREAD# Input: When brought LOW this pin activates Spread Spectrum clocking.
I/O APIC Clock Outputs: Provides 14.318-MHz fixed frequency. The output volt-
age swing is controlled by VDDQ2.
48-MHz Outputs: Fixed clock outputs at 48 MHz. Output voltage swing is controlled
by voltage applied to VDDQ3.
Fixed 14.318-MHz Outputs 0 through 2: Used for various system applications.
Output voltage swing is controlled by voltage applied to VDDQ3.
Frequency Selection Input: Selects power-up default CPU clock frequency as
shown in Table 1 on page 1.
Crystal Connection or External Reference Frequency Input: Connect to either
a 14.318-MHz crystal or reference signal.
Crystal Connection: An input connection for an external 14.318-MHz crystal. If
using an external reference, this pin must be left unconnected.
Power Down Control: When this input is LOW, device goes into a low-power con-
dition. All outputs are held LOW while in power-down. CPU and PCI clock outputs
are stopped LOW after completing a full clock cycle (2–3 CPU clock cycle latency).
When brought HIGH, CPU, SDRAM and PCI outputs start with a full clock cycle at
full operating frequency (3 ms maximum latency).
Power Connection: Connect to 3.3V supply.
Power Connection: Power supply for CPU0:3 and APIC0:1 output buffers. Connect
to 2.5V supply.
Ground Connection: Connect all ground pins to the common system ground
plane.
No Connect: Do not connect.
2