Need +-15-17 from +-20v without voltage divider

[mp006ltk]

Hi, I'm building an active crossover and I already have a regulated power supply near the circuit from the Hypex NC250MP. The problem is that it's +-20v and I need less for most of the opamps I'm looking at.

I've considered just using the 5532 but even those are at the limit with a 40v swing.

I would like to get 15-17v +- without using a voltage divider.

I've looked at voltage regulators (buck style), but I'm not familiar with these.

I would prefer to still use the power supply from the amplifier as it's activated by the other supporting circuitry I have built into my design.

Any recommendations for a converter or easy to use regulator that is okay in an audio circuit?

Thanks!

 

[rayma]

Any typical 3 pin fixed voltage regulator should work here, 20V in, 15V out. There are also many similar equivalents.
https://www.ti.com/lit/ds/symlink/l...l-digikeymode-df-pf-null-wwe&ts=1596582708682
https://www.ti.com/lit/ds/symlink/l...l-digikeymode-df-pf-null-wwe&ts=1596582739108

 

[mp006ltk]

is that better than a TDK CCG154815D

I found this part on digikey from TDK it's called a CCG154815D.

From a design perspective would I get better (cleaner) output from something like this or your recommended regulator?

 

[avtech]

LM7815 and LM7915 following the datasheet 'typical application' scheme for a fixed regulator will do the job. (Just make sure the current handling capability is satisfactory for your application)

Then there are 'LDO' regulators that you can find online for around $10-15.

Or you could add several diodes in series to drop 0.6-0.7v per diode. That one might not be the prettiest solution though.

 

[rayma]

Those are switching converters, with relatively high noise, around 100mV p-p.
The TI three pin regulators have around a 75uV noise spec 10 Hz ≤ f ≤ 100 kHz.
If noise is very critical, you should do a survey of candidate parts and decide
which is best for your application.

 

[mp006ltk]

bypass caps

Should I be using bypass caps with those close to the regulator, or should I just worry about close to the opamp?

Thanks again! All good stuff!

 

[rayma]

Op amps should always have local bypass caps for each supply pin,
typically sometimes 0.1uF, or sometimes 0.1uF + 10uF in parallel.
Sometimes the bypass capacitor is connected from +V to -V, instead of to ground.
All this depends on the particular op amp and how it is used, so check the data sheet.

Some linear voltage regulators require input and/or output capacitors of certain values.
Choose those from the data sheet for the regulator. With some voltage regulators, the
wrong value of output capacitor can cause excessive noise peaking, or even oscillation.
This is because voltage regulators are feedback amplifiers, and their stability is affected
by capacitive loading, just like other feedback amplifiers.