UPD78F0988AGC-8BS Renesas Electronics America, UPD78F0988AGC-8BS Datasheet - Page 102

• Manufacturer Part Number: UPD78F0988AGC-8BS
• Manufacturer: Renesas Electronics America

Specifications of UPD78F0988AGC-8BS

• Lead Free Status / Rohs Status: Supplier Unconfirmed

5.4 System Clock Oscillators
5.4.1 System clock oscillator
X1 and X2 pins.
inverted signal to the X2 pin.
100
The system clock oscillator is oscillated by the crystal or ceramic resonator (12 MHz TYP.) connected across the
An external clock can also be input to the circuit. In this case, input the clock signal to the X1 pin, and input the
Figure 5-3 shows the external circuit of the system clock oscillator.
Cautions 1. The STOP instruction cannot be executed when the external clock is input. This is because
Figure 5-4 shows examples of incorrect resonator connection.
(a) Crystal or ceramic oscillation
2. When using the system clock oscillator, wire as follows in the area enclosed by the broken
if the STOP instruction is executed, the system clock operation is stopped, and the X2 pin
is pulled up to V
lines in the above figures to avoid an adverse effect from wiring capacitance.
•
•
•
•
•
Crystal
or
Ceramic resonator
Keep the wiring length as short as possible.
Do not cross the wiring with the other signal lines.
Do not route the wiring near a signal line through which a high fluctuating current flows.
Always make the ground point of the oscillator capacitor the same potential as V
not ground the capacitor to a ground pattern through which a high current flows.
Do not fetch signals from the oscillator.
Figure 5-3. External Circuit of System Clock Oscillator
DD1
X2
X1
V
.
SS1
CHAPTER 5 CLOCK GENERATOR
User’s Manual U13029EJ7V1UD
External
clock
(b) External clock
X2
X1
SS1
. Do