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High Output current boost PFC with LT1249 IC

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KMN1

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Hi I'm trying t o setup the LT1249 boost PFC controller to work with an input of 24Vrms to obtain an output of 60V at 5A. I've set the reference voltage parameters according to the datasheet here https://www.analog.com/media/en/technical-documentation/data-sheets/1249fbs.pdf
Considering the load is around 12ohms I was not able to obtain a smooth output voltage waveform instead the output voltage is oscillating at a voltage lower then the input voltage.

Does this mean the IC is not capable of handling heavy loads or is the input voltage too low?
If so would a power amplifier set as a voltage follower be a feasible solution? (only problem is it needs to be biased at a voltage above 60V to work)

I've attached an ltspice simulation
1677667408699.png
 
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Here attached i have done your LV PFC with LT1248, In LTspice, LT1248 is similar to LT1249.
You may have to tweak the voltage into the SS pin to get it to 300W.

I didnt put the output divider on as the sim takes ages.

Its fine with 24vac......you just adjust the pin components. Then it doesnt know what is the voltage its working on.
 

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  • LT1248 Boost PFC_24vac.zip
    2.1 KB · Views: 73
  • PFC 2TFC 24vac.zip
    7.5 KB · Views: 70

also, your rsen is 0.4R...that will dissipate at least 74w with 300w and 24vac input.
Also your7.5m inductor looks too high value.
Also, your D1 is not chosen..LTspice doesnt like that.
 

Here attached i have done your LV PFC with LT1248, In LTspice, LT1248 is similar to LT1249.
You may have to tweak the voltage into the SS pin to get it to 300W.

I didnt put the output divider on as the sim takes ages.

Its fine with 24vac......you just adjust the pin components. Then it doesnt know what is the voltage its working on.
Thank you for the reference circuit I really appreciate it. I noticed that there is a huge ripple around 20V, could that be only reduced by sizing the output capacitor?
--- Updated ---

it would appear R1 makes your gain too high
I'm new with configuring PFC controllers on IC, is there a non-analytical way of setting the gains for the current multiplier and voltage error gain?
 
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