Toshiba H1 Series Data Book page 236

The Self Refresh state can be exited by the Self Refresh Exit command. The Self Refresh
Exit command is executed when SDCMM<SCMM2:0> is set to "110". It is also executed
automatically in synchronization with HALT mode release. In either of these two cases,
Auto Refresh is performed immediately after the Self Refresh state is exited. Then, Auto
Refresh is executed at specified intervals. Exiting the Self Refresh state clears
SDCMM<SCMM2:0> to "000".
Setting SDRCR<SSAE> to "0" disables automatic execution of the Self Refresh Exit
command in synchronization with HALT release. The auto exit function should also be
disabled in cases where the SDRAM operation requirements cannot be met as the operation
clock frequency is reduced by clock gear down, as shown in Figure3.10.8.
f
SYS
60MHz
｜
｜
625 KHz (10MHz/16)
CPU
SR
Auto-EXIT
ENTRY
disable
SDRAM controller
internal state
Auto Exit
enable
SDRAM state
Auto Refresh
Figure3.10.8 Execution Flow for Executing HALT Instruction after Clock Gear Down
Gear down
CLK HALT
change
HALT mode
Auto Exit
Self Refresh
92CZ26A-233
Gear up
Interrupt
SR
CLK
EXIT
change
disable
TMP92CZ26A
Auto-EXIT
enable
Auto Exit
enable
Auto Refresh