hys64t512020eu-3s-a Qimonda, hys64t512020eu-3s-a Datasheet - Page 21

• Manufacturer Part Number: hys64t512020eu-3s-a
• Description: 240-pin Unbuffered Ddr2 Sdram Modules
• Manufacturer: Qimonda

30) A maximum of eight Refresh commands can be posted to any given DDR2 SDRAM, meaning that the maximum absolute interval between
31)
32) When the device is operated with input clock jitter, this parameter needs to be derated by the actual
33) When the device is operated with input clock jitter, this parameter needs to be derated by the actual
34) For these parameters, the DDR2 SDRAM device is characterized and verified to support
35)
36) This timing parameter is relaxed than Industry Standard
Rev. 1.0, 2008-06
06112008-YHWK-B105
any Refresh command and the next Refresh command is 9 x
t
(
driving (
calculation is consistent.
deratings are relative to the SDRAM input clock.) For example, if the measured jitter into a DDR2–667 SDRAM has
and
+
deratings are relative to the SDRAM input clock.) For example, if the measured jitter into a DDR2–667 SDRAM has
and
+
cycles, assuming all input clock jitter specifications are satisfied. For example, the device will support
clock cycles, if all input clock jitter specifications are met. This means: For DDR2–667 5–5–5, of which
t
Tm + 5 is valid even if (Tm + 5 - Tm) is less than 15 ns due to input clock jitter.
t
RPST
t
nRP
WTR
RPST
t
t
JIT.PER.MAX
JIT.DUTY.MAX
t
t
= RU{
is at lease two clocks (2 x
JIT.PER.MAX
JIT.DUTY.MAX
end point and
), or begins driving (
t
RPRE
t
RP
= 1.1 x
) by measuring the signal at two different voltages. The actual voltage measurement points are not critical as long as the
/
= 0.6 x
= + 93 ps, then
t
CK.AVG
= + 93 ps, then
t
t
RPRE
CK.AVG
t
} = 5, i.e. as long as the input clock jitter specifications are met, Precharge command at Tm and Active command at
CK.AVG
t
begin point are not referenced to a specific voltage level but specify when the device output is no longer driving
RPRE
+ 93 ps = + 2843 ps. (Caution on the MIN/MAX usage!).
+ 93 ps = + 1592 ps. (Caution on the MIN/MAX usage!).
t
).
RPRE.MIN(DERATED)
t
t
RPST.MIN(DERATED)
CK
Figure 3
) independent of operation frequency.
shows a method to calculate these points when the device is no longer driving (
=
=
t
RPRE.MIN
t
RPST.MIN
+
+
t
t
JIT.PER.MIN
JIT.DUTY.MIN
t
REFI
21
.
= 0.9 x
Method for Calculating Transitions and Endpoint
= 0.4 x
t
CK.AVG
t
CK.AVG
– 72 ps = + 2178 ps and
– 72 ps = + 928 ps and
HYS[64/72]T512020EU–[25F/2.5/3S]–A
t
nPARAM
Unbuffered DDR2 SDRAM Modules
= RU{
t
t
JIT.PER
JIT.DUTY
t
t
nRP
RP
t
PARAM
= 15 ns, the device will support
= RU{
of the input clock. (output
t
t
of the input clock. (output
RPRE.MAX(DERATED)
RPST.MAX(DERATED)
/
t
CK.AVG
Internet Data Sheet
t
RP
t
/
t
JIT.DUTY.MIN
JIT.PER.MIN
t
}, which is in clock
CK.AVG
FIGURE 3
t
RPST
}, which is in
), or begins
=
=
= – 72 ps
= – 72 ps
t
t
RPRE.MAX
RPST.MAX