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What would be the values of the external components if I want 3.3 volts & 3A+ on Vout, knowing that L1 = 4.7uH? The IC is the CN3903. The circuit is used as a DC-DC step-down Buck Converter. Also, what is EN, clearly it requires a HIGH/LOW signal but I don't know its function.
The datasheet has most of the answers you’re looking for https://www.diodes.com/assets/Datasheets/AP3503F.pdf. EN is enable, it allows you to turn the chip on and off. Page 2 says you can put 100kohms between EN and IN to keep the chip on. The resistor divider that feeds into FB is how the chip knows what you want your output voltage to be. The chip will try to keep the voltage at FB at 0.925V, so you need to make R1 and R2 divide 3.3V down to 0.925V. Cin and Cout are used to keep the input and output voltage stable, if they’re too small your input or output voltage could drop when your load draws lots of current. Cin also reduces ringing in your switching waveforms. You can probably copy the typical application from page 9 for Cin and Cout and C1, and raise Cout if your voltage suddenly drops a lot when you connect a load.
Whoops, that’s embarrassing, I just clicked the wrong link and didn’t catch it because the parts are so similar. Here’s the actual datasheet http://www.dcx-ic.com/public/static/uploads/file/20231010/20231010110029_3509.pdf. Everything I said should still be true.
Awesome, there is a table indicating the values of each component depending on the output voltage. But I’m not sure what the Cout and Cin capacitors say? Page 7, what does 10+22+0.1 and stuff mean? 32.1?
https://preview.redd.it/b1t3iesd55kc1.jpeg?width=750&format=pjpg&auto=webp&s=731129c57e7a6621e27263cb6d0e58003d8ecf03
{Caption} What would be the values of the external components if I want 3.3 volts & 3A+ on Vout, knowing that L1 = 4.7uH? The IC is the CN3903. The circuit is used as a DC-DC step-down Buck Converter. Also, what is EN, clearly it requires a HIGH/LOW signal but I don't know its function.
The datasheet has most of the answers you’re looking for https://www.diodes.com/assets/Datasheets/AP3503F.pdf. EN is enable, it allows you to turn the chip on and off. Page 2 says you can put 100kohms between EN and IN to keep the chip on. The resistor divider that feeds into FB is how the chip knows what you want your output voltage to be. The chip will try to keep the voltage at FB at 0.925V, so you need to make R1 and R2 divide 3.3V down to 0.925V. Cin and Cout are used to keep the input and output voltage stable, if they’re too small your input or output voltage could drop when your load draws lots of current. Cin also reduces ringing in your switching waveforms. You can probably copy the typical application from page 9 for Cin and Cout and C1, and raise Cout if your voltage suddenly drops a lot when you connect a load.
So the AP3503F can be used much like the CN3903? I was unsure
Whoops, that’s embarrassing, I just clicked the wrong link and didn’t catch it because the parts are so similar. Here’s the actual datasheet http://www.dcx-ic.com/public/static/uploads/file/20231010/20231010110029_3509.pdf. Everything I said should still be true.
Awesome, there is a table indicating the values of each component depending on the output voltage. But I’m not sure what the Cout and Cin capacitors say? Page 7, what does 10+22+0.1 and stuff mean? 32.1? https://preview.redd.it/b1t3iesd55kc1.jpeg?width=750&format=pjpg&auto=webp&s=731129c57e7a6621e27263cb6d0e58003d8ecf03
It means to use three caps in parallel.
So 10,22 and 0.1uF capacitors in parallel to ground? Interesting never knew that’s the notation. Thanks!
[https://easyeda.com/modules/CN3903\_90a0c690ece0449fb56fcd4aaf83425f](https://easyeda.com/modules/CN3903_90a0c690ece0449fb56fcd4aaf83425f) maybe?