ST & T UPSD3212C - Manual (Page 44)

uPSD3212A, uPSD3212C, uPSD3212CV
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OSCILLATOR
The oscillator circuit of the uPSD321x Devices is a
single stage inverting amplifier in a Pierce oscilla-
tor configuration (see Figure
19 ). The circuitry be-
tween XTAL1 and XTAL2 is basically an inverter
biased to the transfer point. Either a crystal or ce-
ramic resonator can be used as the feedback ele-
ment to complete the oscillator circuit. Both are
operated in parallel resonance.
XTAL1 is the high gain amplifier input, and XTAL2
is the output. To drive the uPSD321x Devices ex-
ternally, XTAL1 is driven from an external source
and XTAL2 left open-circuit.
Figure 19. Oscillator
AI06620
XTAL1 XTAL2
8 to 40 MHz
XTAL1 XTAL2
External Clock