I'm designing a power supply to power small electronics via an 24VAC HVAC transformer. I've done a few reading want to think I have the design right. But since this is the first time I'm designing a power supply and not 100% confident with this and want some feedback on anything that can be revised.

The design should be over engineered that should be able to handle 5A each voltage and; so it should be able to handle the 12VDC and 5VDC up to 3A of max current which is my requirement.


List of component:

• CONN1 - TERM BLOCK 2POS HORIZ 3.5MM T/H (Wurth Electronics Inc 691103110002)
• D1, D2, D3, D4 - DIODE SCHOTTKY 70V 3A SMC (Diodes Incorporated B370-13-F)
• D5, D6 - DIODE SCHOTTKY 40V 3A SMC (Diodes Incorporated SK34-7-F)
• C1 - CAP ALUM 1000UF 20% 50V RADIAL (Rubycon 50ZLH1000MEFC16X25)
• C2, C3 - CAP ALUM 1000UF 20% 16V RADIAL (Rubycon 16ZLH1000MEFC8X20)
• L1, L2 - FIXED IND 100UH 5A 35 MOHM TH (Wurth Electronics Inc 7447070)
• U1 - IC REG BUCK 12V 3A TO220-5 (Texas Instruments LM2576T-12/NOPB)
• U2 - IC REG BUCK 5V 3A TO220-5 (Texas Instruments LM2576T-5.0/NOPB)
  
  
• 2x HEATSINK TO-220 VERT MT BLK 1" (Wakefield-Vette 637-10ABPE)

 

D3/4 are drawn wrong way round, the bridge rectifier can be ordinary 1n5400/7 diodes, but if you feel you need to use Shockley, it looks good....

 

Thanks for the catch on D3/4 - teaches me from working on a PCB design the day I get LASIK done.

Doesn't the 1n5400 have a max reverse voltage of 50V?

Assuming that I understand what I've read well enough, since AC voltage is a sine wave the peak voltage should be - 24 * sqrt(2) = 34V. The maximum reverse voltage apploed on the diode should be 34 - (-34) = 68V.

So Schottky or not, shouldn't I use a diode that can handle at least 70V of max reverse voltage?

 

1n5407 will do for 800V piv...