High Performance Pentium® 4 Clock Synthesizer
52, 51, 49,
48, 45, 44
10, 11, 12,
13, 16, 17,
5, 6, 7
I Oscillator Buffer Input. Connect to a crystal or to an external clock.
O Oscillator Buffer Output. Connect to a crystal. Do not connect when an
external clock is applied at XIN.
O Differential host output clock pairs. See the frequency table on page one
of this data sheet for frequencies and functionality.
O PCI Clock Outputs. Are synchronous to 66IN or 3V66 clock. See
Frequency Table on page one of this data sheet.
O 33Mhz PCI clocks, which are ÷2 copies of 66IN or 3V66 clocks, may be
free running (not stopped when PCI_STP# is asserted low) or may be
stoppable depending on the programming of SMBus register Byte3, Bits
O Buffered Output copy of the device’s XIN clock.
I Current reference programming input for CPU buffers. A resistor is
connected between this pin and VSSIREF. See CPU Clock current Select
Table in page 18 of this data sheet.
I Qualifying input that latches S (0:2) and MULT0. When this input is at a
logic low, the S (0:2) and MULT0 are latched
O Fixed 48MHz USB Clock Outputs.
O Fixed 48MHZ DOT Clock Outputs.
O 3.3 Volt 66 MHz fixed frequency clock.
O 3.3 volt clock selectable with SMBus byte0, Bit5, when Byte5, Bit5. When
Byte 0 Bit 5 is at a logic 1, then this pin is a 48M output clock. When
byte0, Bit5 is a logic 0, then this is a 66M output clock (default).
I This pin is a power down mode pin. A logic low level causes the device to
PU enter a power down state. All internal logic is turned off except for the
SMBus logic. All output buffers are stopped. See the Power Down section
of this data sheet.
I Programming input selection for CPU clock current multiplier. See CPU
PU Clock Current Select Function Table.
I Frequency Select Inputs. See Frequency Table on page 1.
I Serial Data Input. Conforms to the SMBus specification of a Slave
Receive/Transmit device. It is an input when receiving data. It is an open
drain output when acknowledging or transmitting data. See application
I Serial Clock Input. Conforms to the SMBus specification. See application
I Frequency Select input. See Frequency Table on page 1. This is a Tri
T level input that is driven high, low or driven to an intermediate level.
I PCI Clock Disable Input. When asserted low, PCI (0:6) clocks are
PU synchronously disabled in a low state. This pin does not effect PCIF (0:2)
clocks’ outputs if they are programmed to be PCIF clocks via the device’s
Cypress Semiconductor Corporation
Document#: 38-07108 Rev. *A
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