Electrical Specifications
22
Datasheet
For testing purposes, route the TEST3 and TEST5 signals through a ground referenced
Z
0
= 55-
Ω
trace that ends in a via that is near a GND via and is accessible through an
oscilloscope connection.
3.6
FSB Frequency Select Signals (BSEL[2:0])
The BSEL[2:0] signals are used to select the frequency of the processor input clock
(BCLK[1:0]). These signals should be connected to the clock chip and the chipset
system on the platform. The BSEL encoding for BCLK[1:0] is shown in
.
3.7
FSB Signal Groups
In the following chapter, the FSB signals have been combined into groups by buffer
type. AGTL+ input signals have differential input buffers, which use GTLREF as a
reference level. The term AGTL+ Input refers to the AGTL+ input group as well as the
AGTL+ I/O group when receiving. Similarly, AGTL+ Output refers to the AGTL+ output
group as well as the AGTL+ I/O group when driving.
Two sets of timing parameters are specified because of a source synchronous data bus.
One set is for common clock signals that are dependent upon the rising edge of BCLK0
(ADS#, HIT#, HITM#, etc.) and the second set is for the source synchronous signals
that are relative to their respective strobe lines (data and address) as well as the rising
edge of BCLK0.
Asychronous signals are still present (A20M#, IGNNE#, etc.) and can become active at
any time during the clock cycle.
identifies which signals are common clock,
source synchronous, and asynchronous.
Table 3.
BSEL[2:0] Encoding for BCLK Frequency
BSEL[2]
BSEL[1]
BSEL[0]
BCLK Frequency
L
L
L
RESERVED
L
L
H
133 MHz
Table 4.
FSB Pin Groups (Sheet 1 of 2)
Signal Group
Type
Signals
1
AGTL+ Common Clock
Input
Synchronous
to BCLK[1:0]
BPRI#, DEFER#, PREQ#
5
, RESET#, RS[2:0]#,
DPWR#, TRDY#
AGTL+ Common Clock I/O
Synchronous
to BCLK[1:0]
ADS#, BNR#, BPM[3:0]#
3
, BR0#, DBSY#,
DRDY#, HIT#, HITM#, LOCK#, PRDY#
3
AGTL+ Source
Synchronous I/O
Synchronous
to Associated
Strobe
Signals
Associated Strobe
REQ[4:0]#,
A[16:3]#
ADSTB[0]#
A[35:17]#
6
ADSTB[1]#
D[15:0]#, DINV0#
DSTBP0#, DSTBN0#
D[31:16]#, DINV1# DSTBP1#, DSTBN1#
D[47:32]#, DINV2# DSTBP2#, DSTBN2#
D[63:48]#, DINV3# DSTBP3#, DSTBN3#
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