CTRL(1)

Rs ≅1 kΩ

CL ≅16 pF

C2 ≅32 pF

XOUT

XIN

OSCOUT

Y

A

Optional Signal-Conditioning Stage

CLOAD

RLOAD

CLOAD

RF ≅2.2 MΩ

C1 ≅ 32 pF

GND

1

2

3

4

5

6

7

8

VCC

RLOAD

1

2

L

1

2

C C

C

C

C

=

+

12

SN74LVC1404

SCES469F – AUGUST 2003 – REVISED MARCH 2020

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10 Application and Implementation

10.1 Application Information

Figure 4 shows a typical application of the SN74LVC1404 device in a Pierce oscillator circuit. The output voltage

can be conditioned further by connecting OSCOUT to the Schmitt-trigger input inverter. The Schmitt-trigger input

inverter 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

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, that is, RS = XC2. 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.

10.2 Typical Application

Figure 4. Typical Application Diagram