EM78P468NBQSSLASHNBQJ datasheet(37/82 Pages) EMC

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EM78P468N/L

8-Bit Microcontroller

Product Specification (V1.6) 12.31.2007

• 31

(This specification is subject to change without further notice)

Bits 6~4 (CLK2~0) of RD:

main clock selection bits for PLL mode (code option select)

CLK2

CLK1

CLK0

Main clock

Example Fs=32.768kHz

× 130

4.26 MHz

× 65

2.13 MHz

× 65/2

1.065 MHz

× 65/4

532kHz

× 244

8 MHz

6.6.3 Crystal Oscillator/Ceramic Resonators (Crystal)

This LSI can be driven by an external clock signal through the R-OSCI pin as shown in

Fig. 6-7 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. 6-8 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.

EM78P468N

OSCO

R-OSCI

Fig. 6-7 External Clock Input Circuit

Fig. 6-8 Circuit for Crystal/Resonator

Table 5 Capacitor Selection Guide for Crystal Oscillator or Ceramic Resonators

Oscillator Source

Oscillator Type

Frequency

C1 (pF)

C2 (pF)

455kHz

100~150

2.0 MHz

20~40

Ceramic Resonators

4.0MHz

10~30

455kHz

20~40

20~150

1.0MHz

15~30

2.0MHz

Main oscillator

Crystal Oscillator

4.0MHz

Sub-oscillator

Crystal Oscillator

32.768kHz

EM78P468NBQS/NBQJ 数据表(PDF) 37 Page - ELAN Microelectronics Corp

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