EM78P258NN datasheet(63/81 Pages) EMC

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EM78P258N

8-Bit Microprocessor with OTP ROM

Product Specification (V1.0) 06.16.2005

• 57

(This specification is subject to change without further notice)

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.

OSCI

EM78P258N

OSCO

XTAL

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

100~150

2.0 MHz

20~40

Ceramic Resonators

HXT

4.0 MHz

10~30

32.768kHz

100KHz

LXT

200KHz

455KHz

20~40

20~150

1.0MHz

15~30

2.0MHz

Crystal Oscillator

HXT

4.0MHz

Circuit diagrams for serial and parallel modes Crystal/Resonator:

OSCI

EM78P258N

7404

330

XTAL

7404

Fig. 6-15 Serial Mode Crystal/Resonator Circuit Diagram

EM78P258NN Datasheet(PDF) 63 Page - ELAN Microelectronics Corp

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