[sdiy] 3.3V regulator ?

[Michael E. Caloroso]

Linium wrote:
> Hello,
> 
> I need a 3.3v regulator for a DIR1703 (a spdif->i2s/serial convertor made by 
> Texas Instrument). The problem is i don't find this kind of regulator. The 
> circuit board will have this chip and a DAC plus minor parts and that's all. 
> The DAC needs 5V, and only the DIR1703 needs 3.3V.
> 
> I know this kind of regulator does exist but simply are hard to find, i was 
> wondering about alternatives.
> 
> Given that the DIR1703 needs around 50mA for its power and that i don't need 
> top notch parts since the DAC will be used for DC signals, can i :
> 
> -use a divider bridge with resistors from the 5V power line to make 3.3V 
> -use a AOP for the same kind of thing (problem the supply will be 0-5v)
> -use a regulator with variable voltage out, i just discover this possibility, 
> there seems to have some regulators that can be "tuned" with a resistor to 
> produce a voltage in a given range. I don't know at all if they are good or 
> what.

Use a zener regulator, zener diodes are readily available in the low 
voltage range.  There is a 4v rail in the VCO card of my Minimoog that 
originally was a voltage divider off the PS rail.  I replaced the 
voltage divider with a zener regulator, using a silicon diode and 3.3V 
zener in series.  Worked great and I didn't get drift from the TC of 
carbon resistors.

MC