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Topic: Need help with power supply feedback... (Read 541 times) previous topic - next topic

Jbradley532

Hi guys! I've ran into a little problem with a schematic I'm trying to make. I understand all the components of this design accept the power supply feedback "fb" pin by the voltage divider. The power supply i purchased does not have this option and I've seen this pin on some regulator ic's. Can someone explain whether this component of this circuit can go without that part, and if so how it will affect it. I'm not super new at this and have a little experience at this. Any help would be great, I'm attaching the schematic.

CrossRoads

Read the datasheet:

Efficiency Optimizer input
Connect FBI to FBO of the next device when chaining the Efficiency Optimizers.
If unused connect FBI to GND close to the device.

http://www.atmel.com/images/f1_msl3082_db.pdf
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Jbradley532

Thanks crossroads. If u look at any of the schematics in the datasheet all the power supply have a fb node. Mine does not. Its a 12v 30A supply it has 4 ports. Line, neutral, led +, led -. This schematic is showing that the supply has a fb port or pin on it. FBO of the circuit is connected to a voltage divider and the voltage divider is connected to fb of the power supply. If I exclude this part will it cause any harm to the circuit besides efficiency.

CrossRoads

I don't follow - isn't pin5, FBI, connected to a pin that you can connect to ground? That's what all the examples show.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Jbradley532

I might not be wording this correctly. Sorry lol the part circled below is what I'm referring too. How there's a feedback node on the drawled power supply. Mine doesn't have that and I wanna use this ic cause it does everything else I want it to do. If I don't connect that does it mess up the buck / current sense of this application.

CrossRoads

Ok - back to the datasheet then:

Efficiency Optimizer output
Connect FBO through a Schottky diode to the string power supply's feedback node (Figure 4),
or to FBI of the previous device (Figure 5).
If unused leave FBO unconnected.

So leave it unconnected.
Put some component pads in place so you can add parts at a future date.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Jbradley532

Sounds good to me I really appreciate your time. I'm self taught for what I know so I don't always understand what they mean. Thank u

CrossRoads

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

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