UPD17073 NEC, UPD17073 Datasheet - Page 194

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UPD17073

Manufacturer Part Number
UPD17073
Description
4-BIT SINGLE-CHIP MICROCONTROLLER WITH HARDWARE FOR DIGITAL TUNING SYSTEM
Manufacturer
NEC
Datasheet

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Part Number:
UPD17073GB-572-1A7-A
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Quantity:
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20.4 Power-ON Reset
clear voltage). Power-ON clear voltage is described in 20.4.1.
from the voltage detector circuit shown in Figure 20-1.
crystal oscillator starts, and the IRES, RES, and RESET signals are also turned off.
ON clear signal is deasserted, the oscillation stabilization status lasts (for 125 ms or longer). If the basic timer 0 carry
FF setting pulse rises after that, the halt status is released, and power-ON reset is effected.
soon as the power-ON clear signal has been output.
194
Power-ON clear signal
Power-ON reset is effected by raising the supply voltage V
If the supply voltage V
When the power-ON clear signal is output, the crystal oscillator circuit is stopped, and the device stops operation.
While the power-ON clear signal is output, the IRES, RES, and RESET signals are output.
When the supply voltage V
At this time, the halt status that is released by the basic timer 0 carry FF is set by the IRES signal. After the power-
This operation is illustrated in Figure 20-4.
At power-ON reset, the program counter, stack, system register, and peripheral control register are initialized as
For the power-ON reset while the CPU is operating, refer to 20.4.2.
For the power-ON reset in the clock stop status, refer to 20.4.3.
For the power-ON reset when supply voltage V
Reset
signals
Basic timer 0 carry
FF setting pulse
V
CE
X
IRES
RES
RESET
DD
OUT
3 V
0 V
H
L
H
L
H
L
H
L
H
L
H
L
H
L
DD
is lower than the power-ON clear voltage, a power-ON clear signal (POC) is detected
DD
Normal operation
exceeds the power-ON clear voltage, the power-ON clear signal is turned off, the
Figure 20-4. Operation of Power-ON Reset
DD
Device operation stops
rises from 0 V, refer to 20.4.4.
Power-ON clear released.
Oscillation starts.
DD
of the device from a specific level (called power-ON
Halt status
or more
125 ms
Power-ON clear voltage
Power-ON reset
Program starts from address 0.
PD17072,17073

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