12-14
GTL+ INTERFACE SPECIFICATION
NOTES:
1. This is the maximum instantaneous dV/dt over the entire transition range (Hi-to-Lo or Lo-to-Hi) as mea-
sured at the driver’s output
pin
while driving the Ref8N network, with the driver and its package model
located near the center of the network (see Section 12.4., “Ref8N Network”).
2. These are design targets. The acceptance of the buffer is also based on the resultant signal quality. In
addition to edge rate, the shape of the rising edge can also have a significant effect on the buffer’s perfor-
mance, therefore the driver must also meet the signal quality criteria in the next section. For example, a
rising linear ramp of at 0.8V/ns will generally produce worse signal quality (more ringback) than an edge
that rolls off as it approaches V
TT
even though it might have exceeded that rate earlier. Hi-to-Lo edge
rates may exceed this specification and produce acceptable results with a corresponding reduction in
V
OL
. For instance, a buffer with a falling edge rate larger than 1.5V/ns can been deemed acceptable
because it produced a V
OL
less than 500 mV. Lo-to-Hi edges must meet both signal quality and maximum
edge rate specifications.
3. The minimum edge rate is a design target, and slower edge rates can be acceptable, although there is a
timing impact associated with them in the form of an increase in flight time, since the signal at the receiver
will no longer meet the required conditions for T
SU
. Refer to Section 12.1.4., “AC Parameters: Flight
Time” on computing flight time for more details on the effects of edge rates slower than 0.3V/ns.
4. These values are not specific to this specification, they are dependent on the location of the driver along
a network and the system requirements such as the number of agents, the distances between agents,
the construction of the PCB (Z
0
,
ε
r, trace width, trace type, connectors), the sockets being used, if any,
and the value of the termination resistors. Good targets for components to be used in an 8-load 66.6 MHz
system would be: T
CO_MAX
= 4.5 ns, T
CO_MIN
= 1 ns, T
SU
= 2.5 ns, and T
HD
= 0.
5. This value is specified at the output pin of the device. T
CO
should be measured at the test probe point
shown in the Figure 12-11, but the delay caused by the 50
Ω
transmission line must be subtracted from
the measurement to achieve an accurate value for Tco at the output pin of the device. For simulation pur-
poses, the tester load can be represented as a single 25
Ω
termination resistor connected directly to the
pin of the device.
6. See Section 12.2.3., “Determining Clock-To-Out, Setup and Hold” for a description of the procedure for
determining the receiver’s minimum required setup and hold times.
Table 12-5. I/O Buffer AC Parameters
Symbol
Parameter
Min
Max
Units
Figure
Notes
dV/dt
EDGE
Output Signal Edge Rate, rise
0.3
0.8
V/ns
1, 2, 3
dV/dt
EDGE
Output Signal Edge Rate, fall
0.3
-0.8
V/ns
1, 2, 3
T
CO
Output Clock to Data Time
no spec
ns
Figure 12-12
4, 5
T
SU
Input Setup Time
no spec
ns
Figure 12-13
Figure 12-14
4, 6
T
HOLD
Input Hold Time
no spec
ns
4, 6
Summary of Contents for Pentium Pro Family
Page 17: ...1 Component Introduction ...
Page 26: ...2 Pentium Pro Processor Architecture Overview ...
Page 27: ......
Page 36: ...3 Bus Overview ...
Page 62: ...4 Bus Protocol ...
Page 105: ...5 Bus Transactions and Operations ...
Page 126: ...6 Range Registers ...
Page 131: ...7 Cache Protocol ...
Page 135: ...8 Data Integrity ...
Page 148: ...9 Configuration ...
Page 161: ...10 Pentium Pro Processor Test Access Port TAP ...
Page 172: ...11 Electrical Specifications ...
Page 201: ...12 GTL Interface Specification ...
Page 229: ...13 3 3V Tolerant Signal Quality Specifications ...
Page 233: ...14 Thermal Specifications ...
Page 239: ...15 Mechanical Specifications ...
Page 241: ...15 2 MECHANICAL SPECIFICATIONS s Figure 15 1 Package Dimensions Bottom View ...
Page 252: ...16 Tools ...
Page 260: ...16 8 TOOLS Figure 16 4 Generic MP System Layout for Debug Port Connection ...
Page 264: ...17 OverDrive Processor Socket Specification ...
Page 290: ...A Signals Reference ...
Page 320: ...Index ...
Page 328: ......