Crystal Oscillator

A simple crystal oscillator using the LMV7219 is shown

below. Resistors R1 and R2 set the bias point at the com-

parator’s non-inverting input. Resistors R3, R4 and C1 sets

the inverting input node at an appropriate DC average level

based on the output. The crystal’s path provides resonant

positive feedback and stable oscillation occurs. The output

duty cycle for this circuit is roughly 50%, but it is affected by

resistor tolerances and to a lesser extent by the comparator

offset.

IR Receiver

The LMV7219 is an ideal candidate to be used as an infrared

receiver. The infrared photo diode creates a current relative

to the amount of infrared light present. The current creates a

voltage across RD. When this voltage level cross the voltage

applied by the voltage divider to the inverting input, the

output transitions.

10105424

FIGURE 5. Crystal Oscillator

10105425

FIGURE 6. IR Receiver

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