upd63a Renesas Electronics Corporation., upd63a Datasheet - Page 27

• Manufacturer Part Number: upd63a
• Description: 4-bit Single-chip Microcontroller For Infrared Remote Control Transmission
• Manufacturer: Renesas Electronics Corporation.

7. POC CIRCUIT (MASK OPTION)
time of battery replacement. If the applied circuit satisfies the following conditions, the POC circuit can be
incorporated by the mask option.
The POC circuit monitors the power supply voltage and applies an internal reset in the microcontroller at the
• High reliability is not required.
• Clock frequency f
• Power supply voltage V
• Operating ambient temperature T
Cautions 1. The one-time PROM product ( PD6P4B) originally contains the POC circuit.
Remarks 1. It is recommended that the POC circuit be incorporated when applied circuits are infrared remote-
2. There are cases in which the POC circuit cannot detect a low power supply voltage of less
3. Clock oscillation is stopped by the resonator due to low power supply voltage before the
4. If the applied circuit does not satisfy the conditions above, design the applied circuit in such
5. In order to prevent malfunction, be sure to input a low level to more than one of pins K
2. Even when a POC circuit is incorporated, the externally entered RESET input is valid with the OR
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.
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.
a manner that the reset takes effect without failure within the power supply voltage range
by means of an external reset circuit.
K
is released due to supply voltage startup).
control transmitters for household appliances.
condition; therefore, the POC circuit and the RESET input can be used at the same time. However,
if the POC circuit detects a low power supply voltage, the RESET pin will be forced to low level;
therefore, use an N-ch open drain output or NPN open collector output for the external reset circuit.
I3
when reset is released (when RESET pin changes from low level to high level, or POC
X
=2.4 to 4 MHz
DD
= 2.2 to 3.6 V
A
= –20 to +70 ˚C
PD63, 63A, 64
I0
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