Author Topic: Ballpark budgeting for a 3.3VDC power supply  (Read 1389 times)

0 Members and 1 Guest are viewing this topic.

Offline AJMansfieldTopic starter

  • Newbie
  • Posts: 5
  • Country: us
Ballpark budgeting for a 3.3VDC power supply
« on: March 20, 2017, 08:29:37 pm »
I'm working on developing a product that will need to run off mains power (without any external brick) and I'm trying to figure the ballpark amount I need to budget for including a AC mains to 3.3VDC power supply on the board.
The board is already going to be handling mains-voltage stuff as part of its functionality. It only needs to supply around 300 mA for my design (150mA for the MC, 20mA for a character LCD backlight, and then few misc optocouplers and stuff.)
Volume is probably going to be somewhere from 50-5000, and it doesn't need to be terribly efficient or anything.

What is a good ballpark price to use for budgeting this?

I'm mostly using this to sanity-check my target price point to make sure there will actually be a profit margin left after it's all manufactured.

Also, if there are any more general resources about how to budget out a device like this, I'd be glad for any links or other help.
 

Offline t_ryner

  • Regular Contributor
  • *
  • Posts: 58
  • Country: us
Re: Ballpark budgeting for a 3.3VDC power supply
« Reply #1 on: March 21, 2017, 03:53:34 am »
Hello! I did some browsing on digi-key and found these. The first one is a 5 volt regulator to put after the rectifier, and the second is a 3.3v converter that puts out 300mA. Hope I helped!

5 volt reg- https://www.digikey.ca/product-detail/en/texas-instruments/LM2576T-5.0-NOPB/LM2576T-5.0-NOPB-ND/212636

dc-dc converter-  http://www.digikey.com/product-detail/en/cui-inc/VBSD1-S5-S3.3-DIP/102-1373-ND/989828
 

Offline mariush

  • Super Contributor
  • ***
  • Posts: 4983
  • Country: ro
  • .
Re: Ballpark budgeting for a 3.3VDC power supply
« Reply #2 on: March 21, 2017, 07:04:16 am »
TME (a European distributor) sells  classic transformers  ... 1.8va (12v ac 100mA) for 1.19$ if you get 100, probably cheaper if you get 500+ here's example : http://www.tme.eu/en/details/bvei3022002/pcb-transformers/hahn/bv-ei-302-2002/
2.3 va transformers are 1.26$ in 100pcs : http://www.tme.eu/en/details/bvei3032011/pcb-transformers/hahn/bv-ei-303-2011/
  .. a dc-dc converter would cost maybe 1$ (at 100+) so overall you'll be at less than 2.5$
 
farnell has versions with 6v AC output ... A 2.3VA isolation transformer is about 2.5$ when you buy at least 50.  If you order 500 or 5000, I'm sure you can get much lower price.  Here's an example: http://uk.farnell.com/myrra/44157/transformer-2-3va-6v/dp/1689061  (available in 110v or 230v versions)

From there, a bridge rectifier, a capacitor and a linear regulator would be less than 50 cents  if you order hundreds.
No silly certifications to get your product through, easy design (transformer has pcb pins, so it goes directly soldered on pcb, no screws or potential vibration issues etc) , only downside is maybe height of transformer and maybe weight and maybe the fact that your product may not be under 0.5w when in standby or whatever the number is these days (EU certifications)
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf