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TL494 half bridge smps


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Hello everyone,
I was studying a tl494 based half bridge smps 
I came across the current sense section opamp pin 15 & pin16
Now pin16 is connected directly to the ground 
But there is some arrangment made to pin 15

I have drawn a part of it 
Please can anyone help me what is a purpose of “103 trimpot” and why does the transistor “ 2n2222a” is also used which Is connected to microcontroller pic18f452


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A full diagram would have been more helpful to understand the circuit, with your provided circuit its hard to tell. You need to specify at the very least the other pins 16 and 3 of the TL494.

However from the point of connection alone - trimpot touching the 0.1 ohm sense resistors - it looks like current limit control where the trimpot is controlling the current and the MCU setting the high side with GPIO - much like an enable signal. 

Again without further details I can't tell for sure. 

Good luck with your studies 


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