Copyright © 2016, Texas Instruments Incorporated

Copyright © 2016, Texas Instruments Incorporated

23

LPV7215

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SNOSAI6J – SEPTEMBER 2005 – REVISED AUGUST 2016

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Typical Applications (continued)

8.2.3 Crystal Oscillator

A simple crystal oscillator using the LPV7215 is shown in Figure 42. Resistors R1 and R2 set the bias point at the

comparator’s noninverting input. Resistors, R3 and R4 and capacitor C1 set 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.

Figure 42. Crystal Oscillator

8.2.4 IR Receiver

The LPV7215 can also 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 crosses the

voltage applied by the voltage divider to the inverting input, the output transitions.

Figure 43. IR Receiver