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Modelling UC3842 current mode PWM Controller

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Adithya_Pai

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I am trying to model behavior of UC3842 PWM controller http://www.ti.com/lit/ds/symlink/uc3842.pdf
By information from the datasheet done a crude model of loop behavior, But as you can see I have not used error amplifier or without matching the open loop gain given in datasheet If I change any of the gain or offset or sense resistor I wont be able to expect required output. Is there any specific method/documents which may help or sensible approach to take this model to next level.

uc-5.JPG

uc-1.JPG

External setup

uc-2.JPG

Oscillator section

uc-3.JPG
Sense comparator

uc-4.JPG
S_R Latch and or gate

Please suggest some approaches...
 

andre_teprom

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There is available on the web the model of this device in Spice, which at first glance may be a much more reliable approach, which would save you from a lot of time, just to validate your model. If your above simulation tool (I didn't recognize it) doesn't support such a feature, you can just use the spice netlist file as a start point to build your own by hand circuit.
 

treez

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use the LT1243 by linear.com in the free download LTSPice simulator...it is pin for pin compatible
I attachch an ltspice sim of it for you
Change it to .asc and run
 

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dick_freebird

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The Yahoo! LTSpice "Group" has a huge archive of contrib
IC and discrete device models. It may take some digging.
 

asdf44

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PSIM has a model of UCC3842 as well though you'd probably need to pay either to get it or to get much use from it (Though if you have a budget I highly recommend PSIM).

If LT1243 is compatible however then using LTSpice is a no brainier. LTSpice is free but also arguably the best spice tool out there.
 

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