EM78P468LAQ EMC [ELAN Microelectronics Corp], EM78P468LAQ Datasheet - Page 41

• Manufacturer Part Number: EM78P468LAQ
• Description: 8-BIT Microcontroller
• Manufacturer: EMC [ELAN Microelectronics Corp]

Product Specification (V1.0) 03.15.2006
(This specification is subject to change without further notice)
4.6.3
Bit 6~4 (CLK2~0) of RD: main clock selection bits for PLL mode (code option select)
This LSI can be driven by an external clock signal through the R-OSCI pin as shown in
Fig.9 below.
In most applications, the R-OSCI pin and the OSCO pin can be connected with a crystal
or ceramic resonator to generate oscillation. Fig. 10 depicts such circuit. Table 5
provides the recommended values of C1 and C2. Since each resonator has its own
attribute, user should refer to its specification for appropriate values of C1 and C2. RS, a
serial resistor, may be necessary for AT strip cut crystal or low frequency mode.
Table 5 Capacitor Selection Guide for Crystal Oscillator or Ceramic Resonators
Main oscillator
Sub-oscillator
Oscillator source
CLK2
0
0
0
0
1
EM78P468N
Crystal Oscillator/Ceramic Resonators (XTAL)
R-OSCI
OSCO
CLK1
X
0
0
1
1
XTAL
Ceramic
Resonators
Crystal Oscillator
Crystal Oscillator
Rs
Oscillator Type
CLK0
X
0
1
0
1
Fig.9 Circuit for External Clock Input
Fig. 10 Circuit for Crystal/Resonator
EM78P468N
C1
C2
R-OSCI
OSCO
Fs*130
Fs*65
Fs*65/2
Fs*65/4
Fs*244
Main clock
Frequency
32.768kHz
455 kHz
2.0 MHz
455KHz
4.0MHz
1.0MHz
2.0MHz
4.0MHz
EM78P468N
Xout
Xin
Example Fs=32.768K
4.26 MHz
2.13 MHz
1.065 MHz
532 KHz
8 MHz
100~150
XTAL
C1 (pF)
20~40
10~30
20~40
15~30
Rs
15
15
25
8-BIT Microcontroller
C1
C2
EM78P468L
100~150
C2 (pF)
20~150
20~40
10~30
15~30
15
15
25
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