Input impedance of error amplifier in SMPS?

C

cupoftea

Advanced Member level 6
Joined
Jun 13, 2021
Messages
3,057
Helped
62
Reputation
124
Reaction score
139
Trophy points
63
Activity points
15,948
Hi
Do you agree, that in the attached (LTspice and PNG) boost converter,
the input impedance of the error amplifier is 47k + 17500R_in_parallel_with_2500R?
 

Attachments

  • Boost_LT1243.png
    61.7 KB · Views: 93
  • BOOST_LT1243.zip
    1.7 KB · Views: 73

Sort by date Sort by votes
Hi,

this should be correct. You can also check this in your simulation by plotting the voltage at the cathode of D1 divided by the current towards the FB pin e.g. I(R4). Here you will see most likely some impact of the compensation network at higher frequencies. I haven't run your simulation.

BR
 
Upvote 0 Downvote
Thanks, the point is that we need to know the zin of the error amp so we can calc its transfer function so as to do the bode plots.

Thanks, I think you reduced r11 to reduce overshoot....
 

Upvote 0 Downvote
You must log in or register to reply here.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…