SN74LVC1GX04DBVT datasheet(7/13 Pages) TI

7 / 13 page

SN74LVC1GX04

CRYSTAL OSCILLATOR DRIVER

SCES581 − JULY 2004

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

APPLICATION INFORMATION

Figure 3 shows a typical application of the SN74LVC1X04 in a Pierce oscillator circuit. The buffered inverter

(SN74LVC1G04 portion) produces a rail-to-rail voltage waveform. The recommended load for the crystal shown in

this example is 16 pF. The value of the recommended load (CL) can be found in the crystal manufacturer’s data sheet.

Values of C1 and C2 are chosen so that C

L +

1C2

1 ) C2

and C1 ≅ C2. Rs is the current-limiting resistor and the value

depends on the maximum power dissipation of the crystal. Generally, the recommended value of Rs is specified in

the crystal manufacturer’s data sheet and, usually, this value is approximately equal to the reactance of C2 at

resonance frequency, i.e., Rs + XC

. RF is the feedback resistor that is used to bias the inverter in the linear region

of operation. Usually, the value is chosen to be within 1 M

Ω to 10 MΩ.

RF ≅ 2.2 MΩ

CL ≅ 16 pF

C1 ≅ 32 pF

C2 ≅ 32 pF

CLOAD

RLOAD

a) Logic Diagram View

Rs ≅ 1 kΩ

SN74LVC1GU04

Portion

SN74LVC1G04

Portion

Figure 3. Oscillator Circuit

SN74LVC1GX04DBVT Datasheet(PDF) 7 Page - Texas Instruments