how can I get 5V DC from 220V AC? without transformrer.

alanlai1 · ‎2003-10-21

Posted on October 21, 2003 at 09:27

alanlai1 · ‎2003-10-20

Posted on October 21, 2003 at 07:10

I am now doing a project, ( AC power, Thermal Controller )

Only allow to use mcu + thermal resistor + heater. I feel headache that the voltage supply is AC, how can I get 5V DC from 220V AC? without transformrer.

Is it possible to use discrete components to do it?

zener diode? cap? resistor?

because the project is cost-down approach.

sjo · ‎2003-10-20

Posted on October 21, 2003 at 07:26

Have a look at the following app notes:

http://us.st.com/stonline/books/pdf/docs/8313.pdf

http://www.microchip.com/download/appnote/pic16/91008b.pdf

Regards

sjo

alanlai1 · ‎2003-10-20

Posted on October 21, 2003 at 07:48

Thank you very much ~~ that 's a good reference notes~~

but how can I calculate the current can be supported ?

I am worry if it can provide enough current in high power application (temperature control)

sjo · ‎2003-10-21

Posted on October 21, 2003 at 09:27

This type of power supply is dependent on the AC cap, the practical limit is really about 20mA.

The supply can be improved by using full wave rectification but does add cost.

See schematic attached (Simetrix spice model).

Regards

sjo

________________

Attachments :

fullwave.pdf : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006I0Jj&d=%2Fa%2F0X0000000bXF%2Fhqpy3i_ODaIyYiwWtYSr5ZUb9.QybvjsnE.NaeWhpJA&asPdf=false