
45732 AMD 780E Databook 3.10
© 2009 Advanced Micro Devices, Inc.
4-2
Proprietary
PCI Express® Differential Clock AC Specifications
4.3
PCI Express
®
Differential Clock AC Specifications
4.4
Timing Requirements for REFCLK_P Used as OSCIN (14.3181818MHz)
4.5
Side-port Memory Timing for DDR2 Mode
The RS780E’s side-port memory DDR2 interface complies with all the timing requirements given in the JESD79-2B
specification. Please refer to the JEDEC standard for any timing details.
4.5.1
Read Cycle DQ/DQS Delay
During a memory read cycle, there is a DLL inside the RS780E that can delay each DQS signal with respect to its byte of
the DQ valid window. This delay ensures adequate setup and hold time to capture the memory data. This DLL delay is
programmable through the following registers:
MCA_DLL_SLAVE_RD_0. MCA_DLL_ADJ_DQSR_0 <NBMCIND : 0xE0[7:0]>
MCA_DLL_SLAVE_RD_1. MCA_DLL_ADJ_DQSR_1 <NBMCIND : 0xE1[7:0]>
The fraction of strobe delay, in terms of a memory clock period is (24+MCA_DLL_ADJ_DQSR) / 240. For example: if
MCA_DLL_ADJ_DQSR_1 = 36, then DQS1 is delayed by 0.25 x memory_clock_period. So, if the memory clock period
is 5ns, then DQS1 is delayed internally by 1.25ns with respect to DQ[15:8].
Table 4-2 PCI-E Differential Clock (GFX_REFCLK, GPPSB_REFCLK, 100MHz) AC Characteristics
Symbol
Description
Minimum
Maximum
Unit
Rising Edge Rate
Rising Edge Rate
0.6
4.0
V/ns
Falling Edge Rate
Falling Edge Rate
0.6
4.0
V/ns
T
PERIOD AVG
Average Clock Period Aquaria
-300
+2800
ppm
T
PERIOD ABS
Absolute Period (including jitter and spread spectrum
modulation)
9.847
10.203
ns
T
CCJITTER
Cycle to Cycle Jitter
-
150
Ps
Duty Cycle
Duty Cycle
40
60
%
Rise-Fall Matching
Rising edge rate () to falling edge rate
(REFCLK-) matching
-
20
%
Table 4-3 Timing Requirements for REF_CLKP Used as OSCIN (14.3181818MHz)
Symbol
Parameter
Min
Max
Unit
Note
TIP
REFCLK Period
69.82033
69.86224
ns
TIH
REFCLK High Time
2.0
–
ns
TIL
REFCLK Low Time
2.0
–
ns
TIR
REFCLK Rise Time
–
1.5
ns
1
TIF
REFCLK Fall Time
–
1.5
ns
1
TIRR
REFCLK Rising Edge Rate
0.09
4.0
V/ns
TIFR
REFCLK Falling Edge Rate
0.09
4.0
V/ns
TIDC
Duty Cycle
45
55
%
2
TIJCC
REFCLK Cycle-to-Cycle Jitter Requirement
–
300
ps
3
TIJPP
REFCLK Peak-to-Peak Jitter Requirement
–
200
ps
2, 3
TIJLT
REFCLK Long Term Jitter Requirement (1
s after
scope trigger)
–
500
ps
Notes:
1. Measured from -150mV to + 150mV from VREF, which is 0.55V.
2. Measured at VREF, which is 0.55V.
3. Measured with spread spectrum disabled.