WED9LC6816V
White Electronic Designs
Clock Frequency and Latency Parameters - 125MHz SDRAM
(Unit = number of clock)
tRC
70ns
tRAS
50ns
tRP
20ns
tRRD
20ns
tRCD
20ns
tCCD
10ns
tCDL
10ns
tRDL
10ns
CAS
Latency
Frequency
125MHz (8.0ns)
100MHz (10.0ns)
83MHz (12.0ns)
3
3
2
9
7
6
6
5
4
3
2
2
2
2
2
3
2
2
1
1
1
1
1
1
1
1
1
Clock Frequency and Latency Parameters - 100MHz SDRAM
(Unit = number of clock)
tRC
70ns
7
tRAS
50ns
5
tRP
tRRD
tRCD
20ns
2
tCCD
10ns
1
tCDL
10ns
1
tRDL
10ns
1
CAS
Latency
Frequency
20ns 20ns
100MHz (12.0ns)
83MHz (12.0ns)
3
2
2
2
2
2
6
5
2
1
1
Refresh Cycle Parameters
-10
-12
Parameter
Symbol
Min
Max
Min
Max
Units
ms
Refresh Period (1,2)
tREF
—
64
—
64
NOTES:
1. 4096 cycles
2. Any time that the Refresh Period has been exceeded, a minimum of two Auto (CBR) Refresh commands must be given to
"wake-up" the device.
SDRAM Command Truth Table
SDA10
A11-0
Function
SDCE# SDRAS# SDCAS# SDWE # BWE# A12, A13
Notes
Mode Register Set
Auto Refresh (CBR)
L
L
L
L
L
L
H
L
X
X
X
X
X
X
X
X
X
X
X
X
L
OP CODE
L
X
BA
X
X
Single Bank
L
L
L
L
L
L
L
L
L
H
X
X
L
H
H
H
L
L
2
Precharge
Precharge all Banks
L
L
H
Bank Activate
L
H
L
BA
BA
BA
BA
BA
X
Row Address
2
2
2
2
2
3
Write
H
H
H
H
H
H
X
X
X
L
H
L
Write with Auto Precharge
Read
L
L
L
L
Read with Auto Precharge
Burst Termination
No Operation
L
H
L
H
X
X
X
X
X
H
H
X
X
X
H
X
X
X
X
Device Deselect
Data Write/Output Disable
X
X
4
4
Data Mask/Output Disable
H
X
NOTES:
1. All of the SDRAM operations are defined by states of SDCE#, SDWE#, SDRAS#, SDCAS#, and BWE0-3# at the positive rising edge of the clock.
2. Bank Select (BA), A12 (BA0) and A13 (BA1) select between different banks.
3. During a Burst Write cycle there is a zero clock delay, for a Burst Read cycle the delay is equal to the CAS latency.
4. The BWE# has two functions for the data DQ Read and Write operations. During a Read cycle, when BWE# goes high at a clock timing the data outputs are disabled
and become high impedance after a two clock delay. BWE# also provides a data mask function for Write cycles. When it activates, the Write operation at the clock is
prohibited (zero clock latency).
Contact factory for ordering information.
White Electronic Designs Corp. reserves the right to change products or specifications without notice.
September, 2003
Rev. 1
9
White Electronic Designs Corporation • (602) 437-1520 • www.wedc.com
WEDC [ WHITE ELECTRONIC DESIGNS CORPORATION ]
