Astable Multivibrator with TLC271

Thread Starter

VCab22

Joined Apr 6, 2024
4
Hello, I am designing an astable multivibrator using a TLC271. When calculating the period, I take into account the typical values of Voh and Vol. However, when simulating with LTspice (using a model of the TLC271 in high bias), the period has an error of about 15%. I'm not sure if I am overlooking any other important consideration besides the actual values of Voh and Vol. I would appreciate some guidance.
 

ericgibbs

Joined Jan 29, 2010
19,003
Hi VCab,
What is the target period and the High/Low times of your design specification?
E
This is what I see on LTS with your asc file, approx 2.355mSec

EG57_ 1612.png
 
Last edited:

Ian0

Joined Aug 7, 2020
10,041
Hello, I am designing an astable multivibrator using a TLC271. When calculating the period, I take into account the typical values of Voh and Vol. However, when simulating with LTspice (using a model of the TLC271 in high bias), the period has an error of about 15%. I'm not sure if I am overlooking any other important consideration besides the actual values of Voh and Vol. I would appreciate some guidance.
Did you take into account the voltage drop of the diodes?

Just a note: don't get into the habit of using op-amps when you should be using comparators. One day you'll come unstuck! Some op-amps (TL071, for instance) do odd things when the output saturates, and some others (NE5534, for instance) have two diodes back-to-back between the inputs.
 

Thread Starter

VCab22

Joined Apr 6, 2024
4
F=1/2ms=500Hz.
Target duty cycle?

If you don't need the negative voltage output, you could use single supply.
BTW-Opamp output isn't rail-to-rail.
I need my duty cycle to range from 0.2 to 0.8. Therefore, I am attempting to obtain an expression for the period. Following another reply, I suspect the issue may stem from the diodes. However, the expression I obtained with that consideration exhibits greater error.

Edit: I require a negative output voltage, and I have already taken into account that the voltage is not rail-to-rail.
 
Top