PD17225_15 Datasheet, PDF (54/86 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLER FOR SMALL GENERAL-PURPOSE INFRARED REMOTE CONTROL TRANSMITTER

µPD17225, 17226, 17227, 17228
10. LOW-VOLTAGE DETECTOR CIRCUIT (CONNECT RESET AND WDOUT PINS)
The low-voltage detector circuit outputs a low level from the WDOUT pin for initialization (reset) to prevent
program hang-up that may take place when the batteries are replaced, if the circuit detects a low voltage.
A drop in the supply voltage is detected if the status of V_DD = 1.7 to 2.0 V lasts for 1 ms or longer. Note, however,
that 1 ms is the guaranteed value and that the microcontroller may be reset even if the above low-voltage condition
lasts for less than 1 ms.
Although the voltage at which the the reset function is effected ranges from 1.7 to 2.0 V, the program counter
is prevented from hang-up even if the supply voltage drops until the reset function is effected, if the instruction
execution time is from 4 to 32 µs. Note that some oscillators stop oscillating before the reset function is effected.
The low-voltage detector circuit can be set arbitrarily by the mask option.
Caution Connect a capacitor to the RESET pin as shown below to stabilize the operation.
Micro-
computer
RESET
WDOUT
Remark In this figure, the RESET pin is connected to a pull-up resistor by the mask option.
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Data Sheet U12643EJ2V0DS00