EtronTech
EM68916CWQA
NOTE 29: tDAL [tCK] = WR [tCK] + tRP [tCK] = WR + RU {tRP [ps] / tCK(avg) [ps] }, where WR is the value
programmed in the mode register set.
NOTE 30: New units, ‘tCK(avg)’ is introduced in DDR2-667 and DDR2-800. Unit ‘tCK (avg)’ represents the
actual tCK(avg) of the input clock under operation.
NOTE 31: Input clock jitter spec parameter. These parameters and the ones in the table below are referred to
as 'input clock jitter spec parameters' and these parameters apply to DDR2-667 and DDR2-800 only. The
jitter specified is a random jitter meeting a Gaussian distribution.
-25
-3
Parameter
Symbol
Units Note
Min
Max
Min
Max
Clock period jitter
tJIT (per)
-125
125
-100
100
ps
33
Clock period jitter during DLL locking
period
tJIT (per,lck)
tJIT (cc)
-100
-250
100
250
-80
80
ps
ps
33
33
Cycle to cycle clock period jitter
-200
200
Cycle to cycle clock period jitter during
DLL locking period
t
JIT (cc,lck)
-200
-175
-225
200
175
225
-160
-150
-175
160
150
175
ps
ps
ps
33
33
33
Cumulative error across 2 cycles
tERR (2per)
tERR (3per)
Cumulative error across 3 cycles
Cumulative error across 4 cycles
Cumulative error across 5 cycles
tERR (4per)
tERR (5per)
-250
-250
250
250
-200
-200
200
200
ps
ps
33
33
Cumulative error across n cycles,
n=6...10, inclusive
tERR (6-10per)
-350
350
-300
300
ps
33
Cumulative error across n cycles,
n=11...50, inclusive
t
ERR (11-50per) -450
450
125
-450
-100
450
100
ps
ps
33
33
Duty cycle jitter
tJIT (duty) -125
Definitions:
- tCK(avg)
tCK(avg) is calculated as the average clock period across any consecutive 200 cycle window.
N
⎡
⎤
⎥
⎦
avg =
/N
where N=200
(
)
⎢∑
tCK
t
CKj
j =1
⎣
- tCH(avg) and tCL(avg)
tCH(avg) is defined as the average HIGH pulse width, as calculated across any consecutive 200 HIGH
pulses.
N
⎡
⎤
⎥
⎦
avg =
/ N ×
(
avg
CK
where N=200
(
)
(
)
)
⎢∑
tCH
t
t
CHj
j =1
⎣
tCL(avg) is defined as the average LOW pulse width, as calculated across any consecutive 200 LOW pulses.
N
⎡
⎤
⎥
⎦
avg =
/ N ×
(
avg
CK
where N=200
(
)
(
)
)
⎢∑
tCL
t
t
CLj
j =1
⎣
tJIT (duty) is defined as the cumulative set of tCH jitter and tCL jitter. tCH jitter is the largest deviation of
any single tCH from tCH(avg). tCL jitter is the largest deviation of any single tCL from tCL(avg).
- tJIT(duty) = Min/max of {tJIT(CH), tJIT(CL)}
where,
Etron Confidential
31
Rev. 1.1
Apr. 2009
ETRON [ ETRON TECHNOLOGY, INC. ]
