
Operating voltage
range
RESET pin
Warm-up period
(tPWUP)
CPU and peripheral circuits start operating
CPU and peripheral
circuits reset
5
s or more
Figure 2-16 External Reset Input (When the Power Supply Is Stable)
2.4.4.3
Voltage detection reset
The voltage detection reset is an internal factor reset that occurs when it is detected that the supply voltage
has reached a predetermined detection voltage.
Refer to "Voltage Detection Circuit".
2.4.4.4
Watchdog timer reset
The watchdog timer reset is an internal factor reset that occurs when an overflow of the watchdog timer is
detected.
Refer to "Watchdog Timer".
2.4.4.5
System clock reset
The system clock reset is an internal factor reset that occurs when it is detected that the oscillation enable
register is set to a combination that puts the CPU into deadlock.
Refer to "Clock Control Circuit".
2.4.4.6
Trimming data reset
The trimming data reset is an internal factor reset that occurs when the trimming data latched in the internal
circuit is broken down during operation due to noise or other factors.
The trimming data is a data bit provided for adjustment of the ladder resistor that generates the comparison
voltage for the power-on reset and the voltage detection circuits.
This bit is loaded from the non-volatile exclusive use memory during the warm-up time that follows reset
release (tPWUP) and latched into the internal circuit.
If the trimming data loaded from the non-volatile exclusive use memory during the warm-up operation that
follows reset release is abnormal, IRSTSR<TRMDS> is set to "1".
When IRSTSR<TRMDS> is read as "1" in the initialize routine immediately after reset release, the trim-
ming data need to be reloaded by generating an internal factor reset, such as a system clock reset, and activating
the warm-up operation again.
If IRSTSR<TRMDS> is still set to "1" after repeated reading, the detection voltage of the voltage detection
circuit and power-on reset circuit does not satisfy the characteristic specified in the electric characteristics.
Design the system so that the system will not be damaged in such a case.
TMP89FH42
2. CPU Core
2.4 Reset Control Circuit
Page 46
RA004