EtronTech
•
1M x 16 SDRAM
EM636165
Addressing Mode Select Field (A3)
The Addressing Mode can be one of two modes, Interleave Mode or Sequential Mode.
Sequential Mode supports burst length of 1, 2, 4, 8, or full page, but Interleave Mode only
supports burst length of 4 and 8.
A3
0
1
Addressing Mode
Sequential
Interleave
--- Addressing Sequence of Sequential Mode
An internal column address is performed by increasing the address from the column
address which is input to the device. The internal column address is varied by the Burst
Length as shown in the following table. When the value of column address, (n + m), in
the table is larger than 255, only the least significant 8 bits are effective.
Data n
Column Address
0
n
1
n+1
2
n+2
3
n+3
4
n+4
5
n+5
6
n+6
7
n+7
-
-
255
n+255
256
n
257
n+1
-
-
2 words:
Burst Length
4 words:
8 words:
Full Page: Column address is repeated until terminated.
--- Addressing Sequence of Interleave Mode
A column access is started in the input column address and is performed by inverting
the address bits in the sequence shown in the following table.
Data n
Data 0
Data 1
Data 2
Data 3
Data 4
Data 5
Data 6
Data 7
•
A7
A7
A7
A7
A7
A7
A7
A7
A6
A6
A6
A6
A6
A6
A6
A6
A5
A5
A5
A5
A5
A5
A5
A5
Column Address
A4
A4
A4
A4
A4
A4
A4
A4
A3
A3
A3
A3
A3
A3
A3
A3
A2
A2
A2
A2
A1
A1
A0
A0#
4 words
8 words
Burst Length
A1# A0
A1# A0#
A0
A0#
A2# A1
A2# A1
A2# A1# A0
A2# A1# A0#
CAS# Latency Field (A6~A4)
This field specifies the number of clock cycles from the assertion of the Read command to
the first read data. The minimum whole value of CAS# Latency depends on the frequency
of CLK. The minimum whole value satisfying the following formula must be programmed
into this field.
t
CAC
(min)
≤
CAS# Latency X t
CK
A6
0
0
0
0
1
A5
0
0
1
1
X
A4
0
1
0
1
X
CAS# Latency
Reserved
1 clock
2 clocks
3 clocks
Reserved
Preliminary
13
Rev. 1.8
Nov 2001
ETRON [ ETRON TECHNOLOGY, INC. ]
