Datasheet

20 Intel
®
Celeron
®
Processor on 0.13 Micron Process in the 478-Pin Package Datasheet
Electrical Specifications
2.7 Asynchronous GTL+ Signals
The Celeron processor on 0.13 micron process does not use CMOS voltage levels for any signals
that connect to the processor. As a result, legacy input signals such as A20M#, IGNNE#, INIT#,
LINT0/INTR, LINT1/NMI, SMI#, SLP#, and STPCLK# use GTL+ input buffers. Legacy output
FERR# and other non-AGTL+ signals (THERMTRIP# and PROCHOT#) use GTL+ output
buffers. All of these signals follow the same DC requirements as AGTL+ signals. However, the
outputs are not actively driven high (during a logical 0 to 1 transition) by the processor (the major
difference between GTL+ and AGTL+). These signals do not have setup or hold time specifications
in relation to BCLK[1:0]. However, all of the Asynchronous GTL+ signals must be asserted for at
least two BCLKs for the processor to recognize them. See Section 2.11 and Section 2.13 for the DC
and AC specifications for the Asynchronous GTL+ signal groups. See Section 7.2 for additional
timing requirements for entering and leaving the low power states.
2.8 Test Access Port (TAP) Connection
Because of the voltage levels supported by other components in the Test Access Port (TAP) logic,
it is recommended that the Celeron processor on 0.13 micron process be first in the TAP chain and
be followed by any other components within the system. A translation buffer should be used to
connect to the rest of the chain unless one of the other components is capable of accepting an input
of the appropriate voltage level. Similar considerations must be made for TCK, TMS, and TRST#.
Two copies of each signal may be required, with each driving a different voltage level.
2.9 System Bus Frequency Select Signals (BSEL[1:0])
The BSEL[1:0] are output signals that are used to select the frequency of the processor input clock
(BCLK[1:0]). Table 5 defines the possible combinations of the signals, and the frequency
associated with each combination. The required frequency is determined by the processor, chipset,
and clock synthesizer. All agents must operate at the same frequency.
The Celeron processor on 0.13 micron process currently operates at a 400 MHz system bus
frequency (selected by a 100 MHz BCLK[1:0] frequency). Individual processors will operate only
at their specified system bus frequency.
For more information about these pins, refer to Section 5.2 and the appropriate Platform Design
Guide.
Table 5. BSEL[1:0] Frequency Table for BCLK[1:0]
BSEL1 BSEL0 Function
L L 100 MHz
L H RESERVED
H L RESERVED
H H RESERVED