UPD75208 NEC, UPD75208 Datasheet - Page 11

• Manufacturer Part Number: UPD75208
• Description: 4-BIT SINGLE-CHIP MICROCOMPUTER
• Manufacturer: NEC

3.5
to the functions described in sections 3.1 and 3.2.
applied in normal operation, the test mode may be set thereby adversely affecting normal operation.
if cables for the related signals are routed in parallel, wiring noise larger than V
and RESET pins causing errors.
against noise using the following external components.
•
3.6
clock, the signal to be input or output to the P50 pin next to the XT2 pin must be a signal required to be switched
between high and low the minimum number of times (once/second or less).
of capacitance coupling of the P50 and XT2 pins and the correct watch functions cannot be achieved (the watch
becomes fast).
P50 pin as shown below.
P00/INT4 and RESET pins have the function (especially for IC test) to test uPD75208 internal operations in addition
The test mode is set when a voltage larger than V
Since there is a display output pin having a high-voltage amplitude (35 V) next to the P00/INT4 and RESET pins,
Thus, carry out wiring so that wiring noise can be minimized, If noise still cannot be suppressed, take the measure
When selecting the 32.768 kHz subsystem clock connected to the XT1 and XT2 pins as the watch timer source
If the P50 pin signal is switched frequently between high and low, a spike is generated in the XT2 pin because
If it is necessary to allow the P50 pin signal to switch between high and low, mount an external capacitor to the
Connect diode with small V
the pins and V
P00/INT4 PIN AND RESET PIN OPERATING PRECAUTIONS
XT1, XT2 AND P50 PIN OPERATING PRECAUTIONS
P00/INT4, RESET
DD
V
DD
F
V
DD
(0.3 V or less) between
XT1
32.768 kHz
PD75208
DD
is applied to one of these pins. If noise larger than V
XT2
•
P50
Connect a capacitor between the pins and V
P00/INT4, RESET
0.0068
DD
F
may be applied to the P00/INT4
V
DD
V
DD
PD75208
DD
DD
.
is
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