ADC/DAC powersupply with negative outputs

[wlamers]

Hello All,

I have a board with a switched mode supply and a post regulating LDO. Switch mode supply can be set to give max 6V (TI LMZ14201). The LDO is set to 3.3V (TI TPS7a4700). I also require a buffered DAQ that can generate 0-10V or +/-10V (providing >20mA). Therefore I was planning to use a single supply DAQ (on 3.3V) and an external op-amp. Although the op-amp requires a +/-15V supply.

My questions is what would be a suitable design to supply a DAQ (not necessarily the DAQ/op-amp combo I mentioned above). All ideas are welcome. I prefer to have as less as possible additional supplies. So ideally the 3.3v LDO is used as the main supply for the DAC and also the op-amp. Maybe multiplying the output voltage using a coil, like in galvanic isolated designs? Note that it is not required to generate negative voltages with the DAC.

Thanks for your input.

 

[BradtheRad]

Maybe multiplying the output voltage using a coil, like in galvanic isolated designs?

Perhaps a boost converter is what you're thinking of?

This schematic illustrates the concept.



Not shown is the control IC, needed to sense the output voltage, and drive the converter at the proper frequency and duty cycle.

If you absolutely need it to be isolated, there is also a cousin of the above design known as a flyback converter. It uses a transformer with two isolated windings.