PD64A_15 Datasheet, PDF (29/66 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLERS FOR INFRARED REMOTE CONTROL TRANSMISSION

µPD64A, 65
7. POC CIRCUIT
The POC circuit monitors the power supply voltage and applies an internal reset in the microcontroller when the
battery is replaced.
Cautions 1. There are cases in which the POC circuit cannot detect a low power supply voltage of less
than 1 ms. Therefore, if the power supply voltage has become low for a period of less than
1 ms, the POC circuit may malfunction because it does not generate an internal reset signal.
2. Clock oscillation is stopped by the resonator due to low power supply voltage before the
POC circuit generates the internal reset signal. In this case, malfunction may result, for
example when the power supply voltage is recovered after the oscillation is stopped. This
type of phenomenon takes place because the POC circuit does not generate an internal reset
signal (because the power supply voltage recovers before the low power supply voltage is
detected) even though the clock has stopped. If, by any chance, a malfunction has taken
place, remove the battery for a short time and put it back. In most cases, normal operation
will be resumed.
3. In order to prevent malfunction, do not input a high level to all the KI0 to KI3 pins when POC
is released due to supply voltage startup (these pins can be left open. When leaving open,
keep pull-down resistors connected).
Data Sheet U14380EJ3V0DS00
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