LPV7215MFX INTERSIL [Intersil Corporation], LPV7215MFX Datasheet - Page 15

• Manufacturer Part Number: LPV7215MFX
• Description: Micropower, CMOS Input, RRIO, 1.8V, Push-Pull Output Comparator
• Manufacturer: INTERSIL [Intersil Corporation]

THRESHOLD DETECTOR
Instead of tying the inverting input to 0V, the inverting input
can be tied to a reference voltage. As the input on the non-
inverting input passes the V
output changes state. It is important to use a stable reference
voltage to ensure a consistent switching point.
CRYSTAL OSCILLATOR
A simple crystal oscillator using the LPV7215 is shown in
Figure 8. Resistors R
comparator’s non-inverting input. Resistors, R
capacitor C
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 af-
fected by resistor tolerances and to a lesser extent by the
comparator offset.
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
R
the voltage divider to the inverting input, the output transitions.
D
. When this voltage level crosses the voltage applied by
1
set the inverting input node at an appropriate DC
FIGURE 7. Threshold Detector
FIGURE 8. Crystal Oscillator
1
and R
REF
2
threshold, the comparator’s
set the bias point at the
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3
and R
4
and
15
SQUARE WAVE GENERATOR
A typical application for a comparator is as a square wave
oscillator. The circuit in Figure 10 generates a square wave
whose period is set by the RC time constant of the capacitor
C
large signal propagation delay of the comparator and by the
capacitive loading at the output, which limits the output slew
rate.
1
and resistor R
FIGURE 10. Square Wave Oscillator
4
. The maximum frequency is limited by the
FIGURE 9. IR Receiver
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