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Samsung ASIC
5-101
STD150
SRFRAMBW_HD
High-Density Multi-Port Synchronous Register File with Bit-Write
Application Notes
1.
Permitting over-the-cell routing. In SRFRAMBW_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 SRFRAMBW_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 SRFRAMBW_HD.
4.
Contention mode under same addresses (RA[]=WA[] or WA0[] = WA1[]). In SRFRAMBW_HD,
simultaneous operations by both ports on the same address (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.
SRFRAMBW_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.
A byte-write or word-write operation with SRFRAMBW_HD
Refer to the function table. In byte-write operation, the number of BWEN[] signal bus should be divided
by a byte (8) and eight BWEN signals should be tied to a connection wire. In this case, DI[] bus is
controlled by a byte-wired BWEN signal instead of each BWEN bit. In word-write operation, the
functionality is exactly same as SRFRAM_HD. If all of BWEN[] signal is tied to low state, DI[] bus is only
controlled by WEN.
6.
Power reduction during standby mode. SRFRAMBW_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
SRFRAMBW_HD by properly using two standby modes in your design.