Negative and postive voltage from same supply and boost converters.

I have a circuit the needs the following voltages; 5v, -2.5v, 16v and -16v. Currently I am powering this circuit from a bodged mix of batteries and various voltage regulators however if possible I'd like to supply this all from one power supply. My plan is to use two boost converter chips to generate my +/-16v both from probably 9v batteries and to use regulators to help make the 5 and -2.5 voltages but I'd like to ask a few questions first.

1) Can I use a normal boost converter ic such as tps61040 to generate both positive and negative voltages or do I need a special inverting boost converter for negative voltage?

2) Can I tap off of the +/-16v with regulators to generate my +5v/-2.5v? I imagine that this would be quite inefficient and probably cause the regulators to give off a lot of heat; is there some sort of switch mode ic I could use before the regulator to make things more efficient?

3) Can I power both the positive and negative voltages from the same source somehow?

Any help with the above or suggestions for better ways of doing things much appreciated.

Oddwired: I have a circuit the needs the following voltages; 5v, -2.5v, 16v and -16v. Currently I am powering this circuit from a bodged mix of batteries and various voltage regulators however if possible I'd like to supply this all from one power supply. My plan is to use two boost converter chips to generate my +/-16v both from probably 9v batteries and to use regulators to help make the 5 and -2.5 voltages but I'd like to ask a few questions first.

1) Can I use a normal boost converter ic such as tps61040 to generate both positive and negative voltages or do I need a special inverting boost converter for negative voltage?

2) Can I tap off of the +/-16v with regulators to generate my +5v/-2.5v? I imagine that this would be quite inefficient and probably cause the regulators to give off a lot of heat; is there some sort of switch mode ic I could use before the regulator to make things more efficient?

3) Can I power both the positive and negative voltages from the same source somehow?

Any help with the above or suggestions for better ways of doing things much appreciated.

Did you consider using 4 @ 9 Volt batteries? Two for the +18 Volts Two for the -18 Volts With a common Ground between them?

Then use "high efficiency" Switching Buck Inverters to generate the 4 required voltages?

Note: 9 Voltage batteries do not contain very many Amp-Hours.

There are adjustable dual output boost converters. Look here. Low current -2.5volt can be easilly made from a PWM pin and a few diodes/caps. Leo..

Yeah thats what my current setup uses but I don't want to keep paying so much for 9v batteries every time I run out!

You can get [u]inverting regulator chips[/u] or if you aren’t running it on batteries you can build or buy a dual supply and add “normal” positive & negative regulators as needed.

I’ve built quite a few linear +/-15V supplies using a center-tapped transformer, a bridge regulator, a couple of filter capacitors and 7815 & 7915 regulators. Sometimes I’ve added a 7805 for +5V. That works great if you have room for a somewhat bulky transformer and you don’t need too much current (which can overheat the linear regulators).

A couple of years ago I needed a negative supply for an op-amp in a car, so I bought an isolated DC-DC converter module and wired the output “backwards”. Since it’s isolated (with no common ground between the input and output) I simply grounded the positive output and the other output-terminal becomes negative (relative to the car’s ground). You don’t need isolation to make a negative voltage from a positive voltage, but that’s how I chose to handle it. (For efficiency you do need a switching circuit with an inductor.)

You can also get fully isolated DC-DC converters and drive them in parallel from the supply and in series to the
load.

Oddwired: Yeah thats what my current setup uses but I don't want to keep paying so much for 9v batteries every time I run out!

Then why not go rechargeable ?