LM7171: Using the LM7171 as an astable multivibrator with output questions

Michael Morgan1

Part Number: LM7171

Dear Tech Support

I am interested in using the LM7171 designed as a high frequency astable multivibrator, similar to the illustration shown in the data sheet. My question is: there are

no known values attributed to the diodes and zener diodes mounted across the output? Are these set to limit the output swing or, are they there to keep the signal on

the output locked to the zero baseline? How are the values of these diodes determined? Lastly, it seems that the output is a triangle wave at half supply level? Will I

need a second op amp such as, an LM7171 to function as a high frequency amplifier and a wave conversion to a square output with 50% duty cycle?

Regards

Michael

Cayote11@gmail.com

over 6 years ago

0 Sima Jalaleddine over 6 years ago

TI__Mastermind 32435 points

Hello Michael,

Having diodes and zener diodes mounted across the output of the multivibrator would indeed set the limit to the output swing depending on the zener voltage. In Figure 56 in the LM7171 datasheet, this is an example application circuit and the type of diodes chosen are dependent on your application. You could choose zener diodes with higher/lower zener voltages depending on your necessary output range. You could also use schottky diodes instead of the regular diodes or/and zener diodes if it is necessary to have a high switching speeds for high frequency applications; which seems to be for your case. I have attached a schematic of the figure if you would like to play around with the type of diodes available.

Thank you,

Sima