LMV321-N, LMV321-N-Q1, LMV358-N, LMV358-N-Q1
LMV324-N, LMV324-N-Q1
SNOS012I –AUGUST 2000–REVISED FEBRUARY 2013
www.ti.com
PULSE GENERATORS AND OSCILLATORS
A pulse generator is shown in Figure 64. Two diodes have been used to separate the charge and discharge
paths to capacitor C.
Figure 64. Pulse Generator
When the output voltage VO is first at its high, VOH, the capacitor C is charged toward VOH through R2. The
voltage across C rises exponentially with a time constant τ = R2C, and this voltage is applied to the inverting
input of the op amp. Meanwhile, the voltage at the non-inverting input is set at the positive threshold voltage
(VTH+) of the generator. The capacitor voltage continually increases until it reaches VTH+, at which point the
output of the generator will switch to its low, VOL which 0V is in this case. The voltage at the non-inverting input is
switched to the negative threshold voltage (VTH−) of the generator. The capacitor then starts to discharge toward
VOL exponentially through R1, with a time constant τ = R1C. When the capacitor voltage reaches VTH−, the output
of the pulse generator switches to VOH. The capacitor starts to charge, and the cycle repeats itself.
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