
Note:When the STOP mode is released with a low hold voltage, the following cautions must be ob-
served.
The supply voltage must be at the operating voltage level before releasing the STOP mode. The
RESET pin input must also be "H" level, rising together with the supply voltage. In this case, if
an external time constant circuit has been connected, the RESET pin input voltage will increase
at a slower pace than the power supply voltage. At this time, there is a danger that a reset may
occur if the input voltage level of the RESET pin drops below the non-inverting high-level input
voltage (Hysteresis input).
Table 2-4 Oscillation Start Operation at Release of the STOP Mode
Operation mode before the STOP
mode is started
High-frequency
clock
Low-frequency
clock
Oscillation start operation after release
Single-clock mode
NORMAL1
High-frequency
clock oscillation cir-
cuit
-
The high-frequency clock oscillation circuit starts os-
cillation.
The low-frequency clock oscillation circuit stops os-
cillation.
Dual-clock mode
NORMAL2
High-frequency
clock oscillation cir-
cuit
Low-frequency
clock oscillation cir-
cuit
The high-frequency clock oscillation circuit starts os-
cillation.
The low-frequency clock oscillation circuit starts os-
cillation.
SLOW1
-
Low-frequency
clock oscillation cir-
cuit
The high-frequency clock oscillation circuit stops os-
cillation.
The low-frequency clock oscillation circuit starts os-
cillation.
Note:When the operation returns to the NORMAL2 mode, fc is input to the frequency division circuit of the warm-up
counter.
2.3.6.2
IDLE1/2 and SLEEP1 modes
The IDLE1/2 and SLEEP1 modes are controlled by the system control register 2 (SYSCR2) and maskable
interrupts. The following states are maintained during these modes.
1. The CPU and the watchdog timer stop their operations. The peripheral circuits continue to operate.
2. The data memory, the registers, the program status word and the port output latches are all held
in the status in effect before IDLE1/2 or SLEEP1 mode was started.
3. The program counter holds the address of the instruction 2 ahead of the instruction which starts
the IDLE1/2 or SLEEP1 mode.
TMP89FH42
2. CPU Core
2.3 System clock controller
Page 32
RA004