Internet Data Sheet
HYS[64/72]T256020EU-[25F/2.5/3/3S/3.7]-B
Unbuffered DDR2 SDRAM Module
13) The tHZ, tRPST and tLZ, tRPRE parameters are referenced to a specific voltage level, which specify when the device output is no longer driving
(tHZ, tRPST), or begins driving (tLZ, tRPRE). tHZ and tLZ transitions occur in the same access time windows as valid data transitions.These
parameters are verified by design and characterization, but not subject to production test.
14) The Auto-Refresh command interval has be reduced to 3.9 µs when operating the DDR2 DRAM in a temperature range between 85 °C
and 95 °C.
15) 0 °C≤ TCASE ≤ 85 °C
16) 85 °C < TCASE ≤ 95 °C
17) A maximum of eight Auto-Refresh commands can be posted to any given DDR2 SDRAM device.
18) The tRRD timing parameter depends on the page size of the DRAM organization. See Table 2 “Ordering Information for RoHS
Compliant Products” on Page 4.
19) The maximum limit for the tWPST parameter is not a device limit. The device operates with a greater value for this parameter, but system
performance (bus turnaround) degrades accordingly.
20) WR must be programmed to fulfill the minimum requirement for the tWR timing parameter, where WRMIN[cycles] = tWR(ns)/tCK(ns) rounded
up to the next integer value. tDAL = WR + (tRP/tCK). For each of the terms, if not already an integer, round to the next highest integer. tCK
refers to the application clock period. WR refers to the WR parameter stored in the MRS.
21) Minimum tWTR is two clocks when operating the DDR2-SDRAM at frequencies ≤ 200 ΜΗz.
22) User can choose two different active power-down modes for additional power saving via MRS address bit A12. In “standard active power-
down mode” (MR, A12 = “0”) a fast power-down exit timing tXARD can be used. In “low active power-down mode” (MR, A12 =”1”) a slow
power-down exit timing tXARDS has to be satisfied.
3.3.3
ODT AC Electrical Characteristics
ODT AC Character. & Operating Conditions: Table 18 for DDR2–667 & DDR2–800 and Table 19 for DDR2–533 & DDR2–400
TABLE 18
ODT AC Character. and Operating Conditions for DDR2-667 & DDR2-800
Symbol
Parameter / Condition
Values
Unit
Note
Min.
Max.
1)
tAOND
tAON
ODT turn-on delay
2
2
nCK
ns
1)2)
1)
ODT turn-on
tAC.MIN
tAC.MAX + 0.7 ns
tAONPD
tAOFD
tAOF
ODT turn-on (Power-Down Modes)
ODT turn-off delay
t
AC.MIN + 2 ns
2 tCK +
t
AC.MAX + 1 ns
ns
1)
2.5
2.5
nCK
ns
1)3)
1)
ODT turn-off
tAC.MIN
tAC.MAX + 0.6 ns
tAOFPD
tANPD
tAXPD
ODT turn-off (Power-Down Modes)
ODT to Power Down Mode Entry Latency
ODT Power Down Exit Latency
t
AC.MIN + 2 ns
2.5 tCK +
tAC.MAX + 1 ns
ns
1)
3
8
—
—
nCK
nCK
1)
1) New units, 'tCK.AVG' and 'nCK', are introduced in DDR2-667 and DDR2-800. Unit 'tCK.AVG' represents the actual tCK.AVG of the input clock
under operation. Unit 'nCK' represents one clock cycle of the input clock, counting the actual clock edges. Note that in DDR2-400 and
DDR2-533, 'tCK' is used for both concepts. Example: tXP = 2 [nCK] means; if Power Down exit is registered at Tm, an Active command may
be registered at Tm + 2, even if (Tm + 2 - Tm) is 2 × tCK.AVG+ tEPR.2PER(MIN)
.
2) ODT turn on time min is when the device leaves high impedance and ODT resistance begins to turn on. ODT turn on time max is when the
ODT resistance is fully on. Both are measured from tAOND, which is interpreted differently per speed bin. For DDR2-667/800, tAOND is 2 clock
cycles after the clock edge that registered a first ODT HIGH counting the actual input clock edges.
3) ODT turn off time min. is when the device starts to turn off ODT resistance. ODT turn off time max is when the bus is in high impedance.
Both are measured from tAOFD. Both are measured from tAOFD, which is interpreted differently per speed bin. For DDR2-667/800,if tCK.AVG
=
3 ns is assumed, tAOFD= 1.5 ns (0.5 × 3 ns) after the second trailing clock edge counting from the clock edge that registered a first ODT
LOW and by counting the actual input clock edge.
Rev. 1.0, 2006-10
28
10262006-SX8C-DEY8
QIMONDA [ QIMONDA AG ]
