1)24VAC coming in and hook up the diode bridge respectively like that. and the Lm2576 vin and ground hooked up to the diode like the diagram?
2)not sure if L1 should be 10uH or 100uH? what should be its current rating?
3)the 12VDC then goes to to other stage to generate 5V for Pi which needs 1A
also the 12VDC driving the stepper motor which needs 600mA.
So how much 12VDC line need to source? 1A enough?
Is this power circuit correct?
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Burngate
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Re: Is this power circuit correct?
More-or-less correct.
I do have some concerns, however. The major one is that care is needed in the lay-out of the components around the LM2576 - OnSemi's datasheet is helpful if a bit daunting.
As regards the inductor value, work your way through the data sheet, or just go for the bigger one.
Assume the Pi needs 750mA @ 5v. At 90% efficiency, that's about 350mA @ 12v, so with 600mA for the motor, 1A is enough though with not much headroom.
Assuming the 24v AC is 50Hz, C14 has to supply all the current between incoming peaks, so ~500mA for 10ms.
From CV=IT with 500mA, 10ms, and 100uF, the capacitor will lose 50v during that time - rather more vthan you have available. I'd use 1000uF instead - or put one right by the bridge, and the 100uF one right by the chip. And don't forget, the incoming AC is 24v RMS, so the peak voltage will be 35v.
And finally, the 1N4002 is a 1A device - I'd be looking at 1N5401 as a 3A device
I do have some concerns, however. The major one is that care is needed in the lay-out of the components around the LM2576 - OnSemi's datasheet is helpful if a bit daunting.
As regards the inductor value, work your way through the data sheet, or just go for the bigger one.
Assume the Pi needs 750mA @ 5v. At 90% efficiency, that's about 350mA @ 12v, so with 600mA for the motor, 1A is enough though with not much headroom.
Assuming the 24v AC is 50Hz, C14 has to supply all the current between incoming peaks, so ~500mA for 10ms.
From CV=IT with 500mA, 10ms, and 100uF, the capacitor will lose 50v during that time - rather more vthan you have available. I'd use 1000uF instead - or put one right by the bridge, and the 100uF one right by the chip. And don't forget, the incoming AC is 24v RMS, so the peak voltage will be 35v.
And finally, the 1N4002 is a 1A device - I'd be looking at 1N5401 as a 3A device