12-22
GTL+ INTERFACE SPECIFICATION
12.2.4.
System-Based Calculation of Required Input and Output
Timings
Below are two sample calculations. The first determines T
CO-MAX
and T
SU-MIN
, while the sec-
ond determines T
HOLD-MIN
. These equations can be used for any system by replacing the as-
sumptions listed below, with the actual system constraints.
12.2.4.1.
CALCULATING TARGET T
CO-MAX
, AND T
SU-MIN
T
CO-MAX
and T
SU-MIN
can be calculated from the Setup Time equation given earlier in Section
12.1.4., “AC Parameters: Flight Time”:
T
FLIGHT-MAX
< T
PERIOD-MIN
- (T
CO-MAX
+ T
SU-MIN
+ T
CLK_SKEW-MAX
+T
CLK_JITTER-MAX
)
As an example, for two identical agents located on opposite ends of a network with a flight time
of 7.3 ns, and the other assumptions listed below, the following calculations for T
CO-MAX
and
T
SU-MIN
can be done:
Assumptions:
T
PERIOD-MIN
15 ns
(66.6 MHz)
T
FLIGHT-MAX
7.3 ns
(given flight time)
T
CLK_SKEW-MAX
0.7 ns
(0.5ns for clock driver)
(0.2 ns for board skew)
T
CLK_JITTER-MAX
0.2 ns
(Clock phase error)
T
CO-MAX
?? ns
(Clock to output data time)
T
SU-MIN
?? ns
(Required input setup time)
Calculation
7.3 < 15 - (T
CO-MAX
+T
SU-MIN
+0.7 +0.2)
T
CO-MAX
+T
SU-MIN
< 6.8 ns
The time remaining for T
CO-MAX
and T
SU-MIN
can be split ~60/40% (recommendation). There-
fore, in this example, T
CO-MAX
would be 4.0 ns, and T
SU-MIN
2.8 ns.
NOTE
This a numerical example, and does not necessarily apply to any particular
device.
Off-end agents will have less distance to the farthest receiver, and therefore will have shorter
flight times. T
CO
values longer than the example above do not necessarily preclude high-fre-
quency (e.g. 66.6 MHz) operation, but will result in placement constraints for the device, such
as being required to be placed in the middle of the daisy-chain bus.
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: ......