Communities

Writing
Writing
Codidact Meta
Codidact Meta
The Great Outdoors
The Great Outdoors
Photography & Video
Photography & Video
Scientific Speculation
Scientific Speculation
Cooking
Cooking
Electrical Engineering
Electrical Engineering
Judaism
Judaism
Languages & Linguistics
Languages & Linguistics
Software Development
Software Development
Mathematics
Mathematics
Christianity
Christianity
Code Golf
Code Golf
Music
Music
Physics
Physics
Linux Systems
Linux Systems
Power Users
Power Users
Tabletop RPGs
Tabletop RPGs
Community Proposals
Community Proposals
tag:snake search within a tag
answers:0 unanswered questions
user:xxxx search by author id
score:0.5 posts with 0.5+ score
"snake oil" exact phrase
votes:4 posts with 4+ votes
created:<1w created < 1 week ago
post_type:xxxx type of post
Search help
Notifications
Mark all as read See all your notifications »
Users Search
Help Dashboard Sign In Sign Up
Q&A Papers Meta
Q&A
Posts Tags Edits
Ask Question

Post History

71%
+3 −0
Q&A Is it possible to calculate the rise/fall time of an operational amplifier ?

I am planning to use the LM318 operational amplifier to generate a PWM signal and I need to know how to calculate the rise/fall time. LM318/LM218/LM118 datasheet -The slew rate is 70 V/µs maximum...

1 answer  ·  posted 2y ago by deleted user  ·  edited 1y ago by Lorenzo Donati‭

Question opamp rise-time fall-time
#6: Post edited by user avatar Lorenzo Donati‭ · 2023-08-03T13:41:20Z (over 1 year ago)
rise-time fall-time
#5: Post edited by user avatar Peter Mortensen‭ · 2023-01-07T16:06:16Z (almost 2 years ago)
Copy edited (e.g. ref. <https://en.wikipedia.org/wiki/Pulse-width_modulation> and <https://en.wikipedia.org/wiki/Volt>). 
Is it possible to calculate the rise/fall time of an operational amplifier ?
  • Hi guys so i am planning to use LM318 operational amplifier to generate a pwm signal and i need to know how to calculate the rise/fall time thank you.
  • [LM318/LM218/LM118 datasheet](https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.ti.com/lit/gpn/LM318-N&ved=2ahUKEwjN7LqX6L77AhUYVaQEHYrCCPQQFnoECA0QAQ&usg=AOvVaw2teDo15HVgRulQWeLnMu54)
  • **Edit:**
  • -The slew rate is 70v/ųs max.
  • -Slew rate can reach 150v/ųs
  • But with a condition of"feedforward compensation will boost the slew rate to over
  • 150V/μs and almost double the bandwidth."
  • **Edit2:**
  • As suggested from Mr. Olin here my calculation:
  • the LM318 offer 70v/ųs and the output voltage that i need is 18v so:
  • (18 V) / (70V/µs) = 0.257143 ųs = 257.143 ns.
  • And then i did this:
  • (257.143/5)×4 = 205.714 ns.
  • Because rise/fall time start at 10% and end at 90%.
  • And in case of 150v/ųs this gonna be:
  • (18 V) / (150 V/µs) = 0.12 µs = 120 ns
  • (120/5)×4 = 96ns.
  • Is my calculation correct? Thank you.
  • I am planning to use the LM318 operational amplifier to generate a PWM signal and I need to know how to calculate the rise/fall time.
  • [LM318/LM218/LM118 datasheet](https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.ti.com/lit/gpn/LM318-N&ved=2ahUKEwjN7LqX6L77AhUYVaQEHYrCCPQQFnoECA0QAQ&usg=AOvVaw2teDo15HVgRulQWeLnMu54)
  • -The slew rate is 70 V/µs maximum
  • -Slew rate can reach 150 V/µs
  • But with a condition of "feedforward compensation will boost the slew rate to over
  • 150 V/μs and almost double the bandwidth."
  • As suggested from Mr. Olin, here is my calculation:
  • the LM318 offers 70 V/µs and the output voltage that I need is 18 V so:
  • (18 V) / (70 V/µs) = 0.257143 µs = 257.143 ns.
  • And then I did this:
  • (257.143/5)×4 = 205.714 ns.
  • Because the rise/fall time start at 10% and end at 90%.
  • And in case of 150 V/µs this is going to be:
  • (18 V) / (150 V/µs) = 0.12 µs = 120 ns
  • (120/5)×4 = 96 ns.
  • Is my calculation correct?
#4: Post edited by (deleted user) · 2022-11-21T13:37:27Z (about 2 years ago)
  • Hi guys so i am planning to use LM318 operational amplifier to generate a pwm signal and i need to know how to calculate the rise/fall time thank you.
  • [LM318/LM218/LM118 datasheet](https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.ti.com/lit/gpn/LM318-N&ved=2ahUKEwjN7LqX6L77AhUYVaQEHYrCCPQQFnoECA0QAQ&usg=AOvVaw2teDo15HVgRulQWeLnMu54)
  • **Edit:**
  • -The slew rate is 70v/ųs max.
  • -Slew rate can reach 150v/ųs
  • But with a condition of"feedforward compensation will boost the slew rate to over
  • 150V/μs and almost double the bandwidth."
  • **Edit2:**
  • As suggested from Mr. Olin here my calculation:
  • the LM318 offer 70v/ųs and the output voltage that i need is 18v so:
  • (18 V) / (70V/µs) = 0.2571428571 ųs = 257.143 ns.
  • And then i did this:
  • (257.143/5)×4 = 205.714 ns.
  • Because rise/fall time start at 10% and end at 90%.
  • And in case of 150v/ųs this gonna be:
  • (18 V) / (150 V/µs) = 0.12 µs = 120 ns
  • (120/5)×4 = 96ns.
  • Is my calculation correct? Thank you.
  • Hi guys so i am planning to use LM318 operational amplifier to generate a pwm signal and i need to know how to calculate the rise/fall time thank you.
  • [LM318/LM218/LM118 datasheet](https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.ti.com/lit/gpn/LM318-N&ved=2ahUKEwjN7LqX6L77AhUYVaQEHYrCCPQQFnoECA0QAQ&usg=AOvVaw2teDo15HVgRulQWeLnMu54)
  • **Edit:**
  • -The slew rate is 70v/ųs max.
  • -Slew rate can reach 150v/ųs
  • But with a condition of"feedforward compensation will boost the slew rate to over
  • 150V/μs and almost double the bandwidth."
  • **Edit2:**
  • As suggested from Mr. Olin here my calculation:
  • the LM318 offer 70v/ųs and the output voltage that i need is 18v so:
  • (18 V) / (70V/µs) = 0.257143 ųs = 257.143 ns.
  • And then i did this:
  • (257.143/5)×4 = 205.714 ns.
  • Because rise/fall time start at 10% and end at 90%.
  • And in case of 150v/ųs this gonna be:
  • (18 V) / (150 V/µs) = 0.12 µs = 120 ns
  • (120/5)×4 = 96ns.
  • Is my calculation correct? Thank you.
#3: Post edited by (deleted user) · 2022-11-21T13:33:49Z (about 2 years ago)
  • Hi guys so i am planning to use LM318 operational amplifier to generate a pwm signal and i need to know how to calculate the rise/fall time thank you.
  • [LM318/LM218/LM118 datasheet](https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.ti.com/lit/gpn/LM318-N&ved=2ahUKEwjN7LqX6L77AhUYVaQEHYrCCPQQFnoECA0QAQ&usg=AOvVaw2teDo15HVgRulQWeLnMu54)
  • **Edit:**
  • -The slew rate is 70v/ųs max.
  • -Slew rate can reach 150v/ųs
  • But with a condition of"feedforward compensation will boost the slew rate to over
  • 150V/μs and almost double the bandwidth."
  • Hi guys so i am planning to use LM318 operational amplifier to generate a pwm signal and i need to know how to calculate the rise/fall time thank you.
  • [LM318/LM218/LM118 datasheet](https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.ti.com/lit/gpn/LM318-N&ved=2ahUKEwjN7LqX6L77AhUYVaQEHYrCCPQQFnoECA0QAQ&usg=AOvVaw2teDo15HVgRulQWeLnMu54)
  • **Edit:**
  • -The slew rate is 70v/ųs max.
  • -Slew rate can reach 150v/ųs
  • But with a condition of"feedforward compensation will boost the slew rate to over
  • 150V/μs and almost double the bandwidth."
  • **Edit2:**
  • As suggested from Mr. Olin here my calculation:
  • the LM318 offer 70v/ųs and the output voltage that i need is 18v so:
  • (18 V) / (70V/µs) = 0.2571428571 ųs = 257.143 ns.
  • And then i did this:
  • (257.143/5)×4 = 205.714 ns.
  • Because rise/fall time start at 10% and end at 90%.
  • And in case of 150v/ųs this gonna be:
  • (18 V) / (150 V/µs) = 0.12 µs = 120 ns
  • (120/5)×4 = 96ns.
  • Is my calculation correct? Thank you.
#2: Post edited by (deleted user) · 2022-11-21T08:15:42Z (about 2 years ago)
  • Hi guys so i am planning to use LM318 operational amplifier to generate a pwm signal and i need to know how to calculate the rise/fall time thank you.
  • Hi guys so i am planning to use LM318 operational amplifier to generate a pwm signal and i need to know how to calculate the rise/fall time thank you.
  • [LM318/LM218/LM118 datasheet](https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.ti.com/lit/gpn/LM318-N&ved=2ahUKEwjN7LqX6L77AhUYVaQEHYrCCPQQFnoECA0QAQ&usg=AOvVaw2teDo15HVgRulQWeLnMu54)
  • **Edit:**
  • -The slew rate is 70v/ųs max.
  • -Slew rate can reach 150v/ųs
  • But with a condition of"feedforward compensation will boost the slew rate to over
  • 150V/μs and almost double the bandwidth."
#1: Initial revision by (deleted user) · 2022-11-20T19:45:08Z (about 2 years ago) 
Is it possible to calculate the rise/fall time of an operational amplifier ?
Hi guys so i am planning to use LM318 operational amplifier to generate a pwm signal and i need to know how to calculate the rise/fall time thank you.