My First PWM ic model (TL494ish)

QSPICE
1

Hello All,

I would like to share my first attempt at making a PWM ic model.
I set myself the challenge of modeling the TL494 ic from the data sheet using the included devices in QSPICE. (I will explore C later)
My thought was not to make a perfect or accurate model of the TL494 but explore modeling methods and general approach. Please bare that in mind.

The first thing I noticed was my logic gate choice is a little different to the datasheet.
Is it fair to say that the data sheet Functional Block Diagram is a guide rather than accurate?
from TI data sheet:

image
image1035×613 63.4 KB

My attempt:
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image1489×922 69.7 KB

I open my effort to some friendly critique. (Please remember this is playful exploration not hard core modling)
TL494.qsch (40.7 KB)
Parent.TL494.qsch (8.4 KB)

Many thanks Ed.

1 Like
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My option
TL494.qsch (34.5 KB)
TL494.qsym (2.6 KB)
Parent.TL494.qsch (24.0 KB)

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image580×390 22.3 KB

3

Hi Bordodynov,

Thank you for your reply. Apologies for the delay; I’m spending time with family this week and have limited PC access.

That’s a very different approach – I like it! It looks like it models the IC more faithfully than mine, which was aiming for functional similarity.

I particularly like the use of current sources to drive the output transistors. I’ll definitely experiment with this myself.

Thanks,
Ed