HD6433044 Hitachi Semiconductor, HD6433044 Datasheet - Page 176

• Manufacturer Part Number: HD6433044
• Description: (HD64 Series) Hitachi Single-Chip Microcomputer
• Manufacturer: Hitachi Semiconductor

Self-Refresh Mode: Some DRAM devices have a self-refresh function. After the SRFMD bit is
set to 1 in RFSHCR, when a transition to software standby mode occurs, the CAS and RAS
outputs go low in that order so that the DRAM self-refresh function can be used. On exit from
software standby mode, the CAS and RAS outputs both go high.
Table 7-7 shows the pin states in software standby mode. Figure 7-6 shows the signal output
timing.
Table 7-7 Pin States in Software Standby Mode (1) (PSRAME = 0, DRAME = 1)
Signal
HWR
LWR
RD
CS
RFSH
3
CAS/WE = 0
High-impedance
High-impedance
High-impedance
High
High
SRFMD = 0
CAS/WE = 1
High-impedance
High-impedance
High-impedance
High
High
Software Standby Mode
162
CAS/WE = 0
High
High
Low
Low
Low
SRFMD = 1 (self-refresh mode)
CAS/WE = 1
Low
Low
High
Low
Low