EM78P259N/260N
8-Bit Microprocessor with OTP ROM
6.11.2 Crystal Oscillator/Ceramic Resonators (XTAL)
The EM78P259N/260N can be driven by an external clock signal through the OSCI pin
as illustrated below.
OSCI
EM78P259N
EM78P260N
OSCO
Fig. 6-15 External Clock Input Circuit
In most applications, Pin OSCI and Pin OSCO can be connected with a crystal or
ceramic resonator to generate oscillation. Fig. 6-16 below depicts such circuit. The
same applies to the HXT mode and the LXT mode.
C1
OSCI
EM78P259N
EM78P260N
XTAL
RS
OSCO
C2
Fig. 6-16 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 the
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)
455kHz
2.0 MHz
4.0 MHz
32.768kHz
100kHz
200kHz
455kHz
1.0 MHz
2.0 MHz
4.0 MHz
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
62 •
Product Specification (V1.0) 06.16.2005
(This specification is subject to change without further notice)
ELAN [ ELAN MICROELECTRONICS CORP ]
