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STD80/STDM80
5-40
SEC ASIC
SPARAM Gen
Single-Port Asynchronous RAM Generator
Pin Descriptions
Name
CSN
Pin Capacitance
(Unit = SL)
Application Notes
1)
Layout Shape can be fitted by choosing one of 4 Ymux parameters in the above configuration table in
accordance with your chip level layout design preference. Larger one makes the layout shape flat and short.
Smaller one makes it thin and tall. In general, flat and short SPARAM is faster than thin and tall one.
Fitting the Layout Shape (Aspect Ratio)
2)
The maximum capacity of SPARAM (ba=1) reaches to 64K. It can be doubled by setting the bank parameter
(ba) 2 and the bpw double. In that case, note that the words can't be doubled. By the way, the bank
parameter ba=2 can be applied to the configuration smaller than 64K. Please refer to the configuration table
above. SPARAM (ba=2) is a little bigger than SPARAM(ba=1) for the same capacity.
Selecting Number of Banks
I/O
I
Description
"Chip Select Negative" acts as the memory enable signal for selecting one of
multiple memory blocks. When CSN is high, DOUT[ ] goes to Hi-Z state, the
memory goes to stand-by (power down) mode and no access to the memory can
occur. Conversely, if CSN is low only then may a read or write access occur. When
CSN falls, a read access is initiated. CSN should be stable when WEN is low.
"Write Enable Negative" selects the type of memory access. When WEN is high, the
SPARAM is in read mode. Otherwise, it is in write mode. Upon the rising edge of
WEN, a write access completed and a read access initiated. When WEN is low, A[ ]
and CSN should be stable.
"Output Enable Negative" unconditionally enables or disables the output drivers.
"Address" selects the location to be accessed. When A[ ] changes, the transition is
detected and the internal clock pulse will be generated. A[ ] should be stable when
WEN is low.
When WEN rises, the "Data In" word value is written to the location addressed.
During a read access, the data word stored will be presented to the "Data OUT"
ports. DOUT[ ] is tri-statable. When CSN is low and OEN is low, only then, DOUT[ ]
drives a certain value. Otherwise, DOUT[ ] keeps Hi-Z state. During a write access,
the data on DOUT is unpredictable.
WEN
I
OEN
A [ ]
I
I
DI [ ]
DOUT [ ]
I
O
CSN
WEN
OEN
A
DI
DOUT
Ymux 4
5.5
5.5
Ymux 8
11.7
11.7
Ymux 16 Ymux 32
24.1
24.1
1-bank
2-bank
9.7
19.3
4.2
8.4
0.7
1.3
4.2
4.2
1.9
1.9
49.0
49.0