12-23
GTL+ INTERFACE SPECIFICATION
12.2.5.
Calculating Target T
HOLD-MIN
To calculate the longest possible minimum required hold time target value, assume that T
CO-MIN
is one fourth of T
CO-MAX
, and use the hold time equation given earlier. Note that Clock Jitter is
not a part of the equation, since data is released by the driver and must be held at the receiver
relative to the same clock edge:
T
HOLD-MIN
< T
FLIGHT-MIN
+T
CO-MIN
- T
CLK_SKEW-MAX
Assumptions
T
CO-MAX
4.0 ns
(Max clock to data time)
T
CO-MIN
1.0 ns
(Assumed ¼ of max)
T
CLK_SKEW-MAX
0.7 ns
(Driver to receiver skew)
T
FLIGHT-MIN
0.1 ns
(Min of 0.5” at 0.2 ns/inch)
T
HOLD-MIN
?? ns
(Minimum signal hold time)
Calculation
T
HOLD-MIN
< 0.1 +1.0 - 0.7
T
HOLD-MIN
< 0.4 ns
NOTE
This a numerical example, and does not necessarily apply to any particular
device.
12.3.
PACKAGE SPECIFICATION
This information is also included for designers of components for a GTL+ bus. The package that
the I/O transceiver will be placed into must adhere to two critical parameters. They are package
trace length, (the electrical distance from the pin to the die), and package capacitance. The spec-
ifications for package trace length and package capacitance are not explicit, but are implied by
the system and I/O buffer specifications.
12.3.1.
Package Trace Length
The System specification requires that all signals be routed in a daisy chain fashion, and that no
stub in the network exceed 250 ps in electrical length. The stub includes any printed circuit board
(PCB) routing to the pin of the package from the ‘Daisy Chain’ net, as well as a socket if nec-
essary, and the trace length of the package interconnect (i.e. the electrical length from the pin,
through the package, across a bond wire if necessary, and to the die). For example, for a PGA
package, which allows PCB routing both to and from a pin and is soldered to the PCB, the
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: ......