HD6417615 Hitachi Semiconductor, HD6417615 Datasheet - Page 316

• Manufacturer Part Number: HD6417615
• Description: Hardware Manual
• Manufacturer: Hitachi Semiconductor

Note: * DACKn waveform when active-low is specified.
7.5.5
Synchronous DRAM writes are executed as single writes or burst writes according to the
specification by the BWE bit in BCR3. Figure 7.22 shows the basic timing chart for single write
accesses. After the ACTV command Tr, a WRITA command is issued in Tc to perform an auto-
precharge. In the write cycle, the write data is output simultaneously with the write command.
When writing with an auto-precharge, the bank is precharged after the completion of the write
command within the synchronous DRAM, so no command can be issued to that bank until the
precharge is completed. For that reason, besides a Tap cycle to wait for the precharge during read
accesses, a Trw1 cycle is added to wait until the precharge is started, and the issuing of any new
commands to the same bank is delayed during this period. The number of cycles in the Trw1 cycle
can be specified using the TRWL1 and TRWL0 bits in MCR.
CKIO
A24–A11
A10
A9–A1
CS2 or CS3
RAS
CAS
RD/WR
DQMxx
D31–D0
DACKn*
Single Writes
Figure 7.21 (b) Single Read Timing (Auto-Precharge) I : E = 1 : 1
Tr
Tc
Td1
Td2
Td3
Td4
Tde
Tde
Tap
299