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CERAMIC RESONATOR PRINCIPLES - page 5 / 7

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1.251 ~ 1.499MHz

1500pF

2000pF

4.7k

22K

1.500 ~ 1.99MHz

1500pF

1500pF

4.7K

22K

1.80 ~ 2.49MHz

1000pF

1000pF

4.7K

22K

2.50 ~ 3.99Mhz

1000pF

1000pF

4.7K

10K

4.00 ~ 4.99Mhz

680pF

680pF

4.7K

10K

5.00 ~ 6.30Mhz

470pF

470pF

4.7K

10K

6.31 ~ 6.99Mhz

470pF

470pF

4.7K

10K

7.00 ~ 8.99MHz

330pF

330pF

4.7K

10K

9.00 ~ 11.99MHz

220pF

220pF

4.7K

10K

12.00 ~ 13.99Mhz

220pF

220pF

2.2K

22K

14.00 ~ 17.99Mhz

150pF

150pF

2.2K

22K

18.00 ~ 21.99MHz

100pF

100pF

2.2K

22K

22.00 ~ 25.99Mhz

68pF

68pF

4.7K

22K

26.00 ~ 32.00MHz

47pF

47pF

4.7K

22K

CL1

CIRCUIT CONSTANT

CL2

Rf

Rd

Figure 5.1) TTL Standard Circuit

CERAMIC RESONATOR APPLICATIONS

OUTPUT

V

DD

14

SN74LSO4N (T.I.)

1

2

3

4

7

FREQUENCY RANGE

R

d

CL1

R

f

CL2

Circuits for Various IC/ LSI:

Ceramic resonators are being used in a wide range of applications in combination with various kinds of IC’s by making good use of the previously mentioned features. Following are a few examples of actual applications.

Applications for Microprocessors: Ceramic resonators are optimum as a stable oscillating element for various kinds of microprocessors: 4 bit, 8 bit, and 16 bit. As the general frequency tolerance required for the reference clock of microprocessors is ±2% - 3%, standard units meet this requirement. Ask your ECS or LSI manufacturers about circuit constants because they vary with frequency and the LSI circuit being used. Fig. A shows an application with a 4 bit microprocessor, and Fig. B shows an application with an 8 bit microprocessor.

VCO (Voltage Controlled Oscillator) Circuits: VCO circuits are used in TV’s and audio equipment because the signals need to be processed in synchronization with pilot signals transmitted from broadcasting stations. Oscillation circuits, such as LC and RC were originally used; however, ceramic resonators are now used since they require no adjustment and have superior stability over the older type circuits. Resonators for VCO applications are required to have a wide variable frequency

Miscellaneous: Other than the above mentioned uses, ceramic resonators are widely used with IC’s for voice synthesis and clock generation. For general timing control applications, oscillation frequency is usually selected by the user based on the IC manufacturer’s recommended operating frequency range. The selection of this frequency with a given IC will dictate what circuit values and which ceramic resonator will be appropriate. Please contact your local ECS Sales representative when selecting a ceramic resonator part number.

Remote Control IC: Remote controls have increasingly become a common feature. Oscillation frequency is normally 400-500 KHz, with 455KHz being the most popular. This 455KHz is divided by a carrier signal generator so that approximately 38KHz of carrier is generated.

As mentioned earlier, there are many applications for ceramic resonators. Some of the more application specific oscillator circuits require that unique ceramic resonators be developed for that application and IC.

+5V

+5V

V

DD

(+5V)

100K

VDD

RESET

40

IC: MC68HC05C4

61

44

43

42

41

26

25

24

23

22

6805

38

39

20

R

f

TMP47C420F

VSS

E

ExTAL 4.00M

xTAL

9

11

12

18 19 20 21

fOCS

30pF

30pF

CL1

CL2

30pF

4.00M

30pF

Figure A) TMP47C420F (TOSHIBA)

  • (1)

    MC6805 (Motorola)

  • (2)

    HD6805 (Hitachi)

Figure B) 6805s by Various Manufacturers (Timing Control)

C1 = 30pF C2 = 30pF R1 = 1M

Figure C) By Various Manufacturers (Timing Control, 8bit)

ECS, INC. INTERNATIONAL 1105 S. RIDGEVIEW, OLATHE, KS 66062 • 913-782-7787 • 800-237-1041 • FAX 913-782-6991 • WWW.ECSXTAL.COM

TECHNICAL REFERENCE

92

TECHNICAL REFERENCE

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