Toshiba TLCS-900/H1 Series Manual page 388

(3) Refresh control
This LSI supports two refresh commands: auto-refresh and self-refresh.
(a) Auto-refresh
The auto-refresh command is automatically generated at intervals set by
SDRCR<SRS2:0> by setting SDRCR<SRC> to "1". The generation interval can be
set from between 47 to 312 states (2.4 μs to 15.6 μs at f
CPU operation (instruction fetch and execution) stops while performing the
auto-refresh command. The auto-refresh cycle is shown in Figure 3.16.4 and the
auto-refresh generation interval is shown in Table 3.16.2. The Auto-Refresh
function cannot be used in IDLE1 and STOP modes. In these modes, use the Self-
Refresh function to be explained next.
Note: A system reset disables the Auto-Refresh function.
SDRCR<SRS2:0>
SRS2 SRS1 SRS0
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
SDCLK
SDCKE
SDUUDQM
SDULDQM
SDLUDQM
SDLLDQM
SDCS
SDRAS
SDCAS
SDWE
Timing of Auto-Refresh Cycle
Figure 3.16.4
Refresh Cycle Insertion Interval
Table 3.16.2
Insertion
Interval
6 MHz
(State)
47 7.8
78 13.0
97 16.2
124 20.7
156 26.0
195 32.5
249 41.5
312 52.0
92CH21-386
2 states
Auto-refresh
f Frequency (System clock)
SYS
10 MHz 12.5 MHz 15 MHz 17.5 MHz 20 MHz
4.7 3.8
7.8 6.2
9.7 7.8
12.4 9.9
15.6 12.5 10.4
19.5 15.6 13.0
24.9 19.9 16.6
31.2 25.0 20.8
TMP92CH21
= 20 MHz).
SYS
(Unit: μs)
3.1 2.7 2.4
5.2 4.5 3.9
6.5 5.5 4.9
8.3 7.1 6.2
8.9 7.8
11.1 9.8
14.2 12.4
17.8 15.6
2009-06-19