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STD150
5-84
Samsung ASIC
SRFRAM_HD
High-Density Multi-Port Synchronous Register File
Block Diagrams
SRFRAM_HD supports only 1-bank architecture. The power ports are located on the top-edge and the
bottom edge of both right- and left-sides of the memory. All signal ports are only located on the bottom sides
of the memory.
Application Notes
1.
Permitting over-the-cell routing. In SRFRAM_HD, the over-the-cell routing is permitted for Metal-4 or
upper layers. Namely, while doing layout on the chip-level, any signals to be routed can be crossed over
the area of register file generated by SRFRAM_HD compiler.
2.
Incoming power bus should be adjusted to guarantee NOT more than 10% voltage drop at typical-case
current levels.
3.
Power stripe should be tapped from both sides of SRFRAM_HD.
4.
Contention mode under same addresses (RA[]=WA[] or WA0[] = WA1[]). In SRFRAM_HD, simultaneous
operations by both ports on the same addresses (RA[]=WA[] or WA0[] = WA1[]) such as read/write,
write/read and write/write operation, cause a contention problem. Simultaneous operations are defined
as the state in which both ports are enabled and both address buses are equal. SRFRAM_HD has no
scheme preventing the contention mode. Due to the simultaneous operations, silicon will behave
unpredictably. A write operation cannot complete and data appearing at outputs may not be valid.
Please refer to the timing diagrams if you want to avoid the contention mode between both ports.
5.
Power reduction during standby mode. SRFRAM_HD provides two types of standby modes – the write
standby mode and the read standby mode. While in the write standby mode, WA[] and DI[] are blocked
even though the transitions of those signals occur. While in the read standby mode, RA[] is blocked even
though its transition occurs. So, you can reduce the power consumption in SRFRAM_HD by properly
using two standby modes in your design.
VSS
VDD
VDD
VSS
W
W
RAM Core
R
R
Write
Control Block
Block
Column Mux
Read
Control Block
I/O Driver
VSS
VDD
VSS
VSS
VDD
VDD
VSS
VSS
VDD
VDD
VSS
W
W
D
R
W
R
R
O
D