eorex
Preliminary
EM488M3244VBC
AC Operating Test Characteristics (Continued)
(VDD=3.3V±0.3V, TA=0°C ~70°C, -25°C ~ +85°C)
-7.5
Symbol
tRC
Parameter
Units
ns
Min.
67.5
Max.
ACTIVE to ACTIVE Command
Period (Note 6)
ACTIVE to PRECHARGE
Command Period (Note 6)
tRAS
tRP
45
22.5
22.5
15
100K
ns
PRECHARGE to ACTIVE
Command Period (Note 6)
ns
ACTIVE to READ/WRITE Delay
Time (Note 6)
tRCD
tRRD
tCCD
ns
ACTIVE(one) to ACTIVE(another)
Command (Note 6)
ns
READ/WRITE Command to
READ/WRITE Command
1
CLK
Date-in to PRECHARGE
Command
tDPL
tBDL
tROH
tREF
2
CLK
CLK
Date-in to BURST Stop Command
1
3
2
Data-out to High
Impedance from
PRECHARGE Command
CL=3
CL=2
CLK
ms
Refresh Time (4,096 cycle)
64
* All voltages referenced to VSS.
Note 6: These parameters account for the number of clock cycles and depend on the operating frequency
of the clock, as follows:
The number of clock cycles = Specified value of timing/clock period (Count Fractions as a whole
number)
Recommended Power On and Initialization
The following power on and initialization sequence guarantees the device is preconditioned to each user’s
specific needs. (Like a conventional DRAM) During power on, all VDD and VDDQ pins must be built up
simultaneously to the specified voltage when the input signals are held in the “NOP” state. The power on
voltage must not exceed VDD+0.3V on any of the input pins or VDD supplies. (CLK signal started at same
time)
After power on, an initial pause of 200 µs is required followed by a precharge of all banks using the
precharge command.
To prevent data contention on the DQ bus during power on, it is required that the DQM and CKE pins be
held high during the initial pause period. Once all banks have been precharged, the Mode Register Set
Command must be issued to initialize the Mode Register. A minimum of eight Auto Refresh cycles (CBR)
are also required, and these may be done before or after programming the Mode Register.
May. 2007
www.eorex.com
8/19
EOREX [ EOREX CORPORATION ]
