Converting 5 and 3.3 Volts to 1.9 Volts

khaag · Post by **khaag** » Fri Jan 16, 2009 8:59 am

How would I go about converting 5V and 3.3V into 1.9V? That is to say, I want two separate 1.9V outputs from 2 separate input voltages.

7805 (5V) regulator --> [Some circuit] --> 1.9V

and

LM3940 (3.3V) regulator --> [Some circuit] --> 1.9V

Post by **Skyone** » Fri Jan 16, 2009 9:41 am

Code: Select all

Voltage     Part Number

1.9         LMS1585
3.3         LM1086
5.0         LM7805

1.9v - LM1585A Schematic

3.3v - LM1086 Schematic

5v - LM7805 Schematic

EDIT: Apparently my 1.9v schematic is wrong; Google for the LM1585A's datasheet for correction.

khaag · Post by **khaag** » Fri Jan 16, 2009 10:09 am

I do believe you've read my mind.

Thanks, Sky.

nitro2k01 · Post by **nitro2k01** » Fri Jan 16, 2009 10:35 am

Sure you got the 1587 right? Isn't the 120 ohm resistor supposed to go to pin 1 of the regulator rather than to ground?

Post by **Skyone** » Fri Jan 16, 2009 4:55 pm

Skyone wrote:EDIT: Apparently my 1.9v schematic is wrong; Google for the LM1585A's datasheet for correction.

Yeah; I was probably in a rush while drawing the diagram or something. Sorry! >_<"

schmellyfart · Post by **schmellyfart** » Fri Jan 16, 2009 6:20 pm

What are the caps for?

Post by **Skyone** » Fri Jan 16, 2009 11:55 pm

Stability generally; might not be required if the regulator is physically close to the power supply filter.

schmellyfart · Post by **schmellyfart** » Sat Jan 17, 2009 1:29 am

Oh ok. Thanks.

khaag · Post by **khaag** » Sat Jan 17, 2009 2:00 am

Now what if I have 7.4V LiPoly cells... is it still the same circuit?