IBM EM78P447N manual Crystal Oscillator/Ceramic ResonatorsXTAL, Crystal/Resonator Circuit

Models: EM78P447N

1 58
Download 58 pages 20.07 Kb
Page 28
Image 28
4.7.2 Crystal Oscillator/Ceramic Resonators(XTAL)

EM78P447N

8-Bit Microcontroller with OTP ROM

Table 11 The Summary of Maximum Operating Speeds

Conditions

VDD

Fxt max.(MHz)

Two cycles with two clocks

2.3

4.0

3.0

8.0

5.0

20.0

4.7.2 Crystal Oscillator/Ceramic Resonators(XTAL)

EM78P447N can be driven by an external clock signal through the OSCI pin as shown in Fig. 10 below.

In most applications, Pin OSCI and Pin OSCO can be connected with a crystal or ceramic resonator to generate oscillation. Fig. 12 depicts such circuit. The same thing applies whether it is in the HXT mode or in the LXT mode. Table 12 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.

OSCI

OSCO

EM 78P447S

Ext. Clock

Fig. 10 Crystal/Resonator Circuit

OSCI

EM 78P447S

OSCO

 

C1

XTAL

 

RS

C2

 

Fig. 11 Crystal/Resonator Circuit

24

Product Specification (V1.1) 03.30.2005

(This specification is subject to change without further notice)

Page 28
Image 28
IBM EM78P447N manual Crystal Oscillator/Ceramic ResonatorsXTAL, Crystal/Resonator Circuit