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Samsung ASIC
5-17
STD150
SPSRAMBW_HD
High-Density Single-Port Synchronous Static RAM with Bit-Write
Logic Symbol
Function Description
SPSRAMBW_HD is a single-port synchronous static RAM with bit-write capability which is provided as a
compiler. SPSRAMBW_HD is intended for use in high-density applications. Basically, its functionality is
exactly same as SPSRAM_HD except a bit-write operation which is controlled by BWEN[], named bit-write
enable signal bus. Each bit of BWEN[] enables or disables the write operation of its corresponding bit in DI[].
On the rising edge of CK, the write cycle is initiated when WEN is low and CSN is low. When the individual
bit of BWEN[] is low, the data on the corresponding write data bit of DI[] are written into the memory location
specified on A[]. When all bits of BWEN[] are high, any data in DI[] are not written into the memory location
specified on A[]. When all bits of BWEN[] are low, the data in DI[] are written into the memory location
specified on A[], which is exactly same as the write operation in SPSRAM_HD. During the write cycle,
DOUT[] remains stable. On the rising edge of CK, the read cycle is initiated when WEN is high and CSN is
low. The data at DOUT[] become valid after a delay. While in standby mode that CSN is high, A[] and DI[] are
disabled, data stored in the memory is retained and DOUT[] remains stable. When OEN is high, DOUT[] is
placed in a high-impedance state.
SPSRAMBW_HD Function Table
CK
X
X
↑
↑
↑
↑
CSN
X
H
L
L
L
L
WEN
X
X
L
L
L
H
OEN
H
L
L
L
L
L
A
X
X
BWEN
X
X
all L
L
all H
X
DI
X
X
DOUT
Z
DOUT(t-1)
DOUT(t-1)
DOUT(t-1)
DOUT(t-1)
MEM(A)
Comment
Unconditional tri-state output
De-selected (standby mode)
Word-write cycle
Bit-write cycle
No operation
Read cycle
Valid
Valid
Valid
Valid
Valid
Valid
Valid
X
Features
High-density application
Bit-Write capability
Separated data I/O
Synchronous operation
Duty-free clock cycle
Asynchronous tri-state output control
Latched inputs and outputs
Automatic power-down
Near zero hold time
Low noise output optimization
Flexible aspect ratio
Up to 256Kbits capacity
Up to 16K number of words
Up to128 number of bit per word
CK
CSN
WEN
BWEN [b-1:0]
OEN
A [m-1:0]
spsrambw_hd_<w>x<b>m<y>
DOUT [b-1:0]
NOTES:
1. Words(w) is the number of words.
2. Bpw(b) is the number of bits per word.
3. Ymux(y) is one of the column mux types.
4. m =
log
2
w
DI [b-1:0]