EM78P258N
8-Bit Microprocessor with OTP ROM
In the most applications, Pin OSCI and Pin OSCO can be connected with a crystal or
ceramic resonator to generate oscillation. Fig. 6-14 below depicts such circuit. The
same applies to the HXT mode and the LXT mode.
C1
OSCI
EM78P258N
XTAL
OSCO
RS
C2
Fig. 6-14 Crystal/Resonator Circuit
The following table provides the recommended values for C1 and C2. Since each
resonator has its own attribute, you should refer to the resonator specifications for
appropriate values of C1 and C2. RS, a serial resistor, may be required for AT strip cut
crystal or low frequency mode.
Capacitor selection guide for crystal oscillator or ceramic resonators:
Oscillator Type
Frequency Mode
Frequency
C1(pF)
C2(pF)
455 kHz
2.0 MHz
4.0 MHz
32.768kHz
100KHz
200KHz
455KHz
1.0MHz
2.0MHz
4.0MHz
100~150
20~40
10~30
25
100~150
20~40
10~30
15
Ceramic Resonators
HXT
LXT
HXT
25
25
25
25
Crystal Oscillator
20~40
15~30
15
20~150
15~30
15
15
15
Circuit diagrams for serial and parallel modes Crystal/Resonator:
330
330
C
OSCI
7404
7404
7404
EM78P258N
XTAL
Fig. 6-15 Serial Mode Crystal/Resonator Circuit Diagram
Product Specification (V1.0) 06.16.2005
• 57
(This specification is subject to change without further notice)
ELAN [ ELAN MICROELECTRONICS CORP ]
