12 to 48V DC/DC Converter For Phantom Power

[mediatechnology]

I clipped this circuit some time ago thinking it might be useful. It is a +12 to -48V DC/DC converter for telecom applications that could be easily modified to be a +48V supply for phantom power use.


-48V Power Supply, "DC/DC Converter for Telecom Applications," Charles Hill, Darin Kincaid, ST Microelectronics Application Note.

Full text of -48V Power Supply Using SG3524

There may be more elegant and simple solutions using modern switchers, but the SG3524 is widely available from many, many sources and the inductor requirements allow off-the-shelf components to be used.

To provide +48V for phantom, D22 and C42 could be reversed along with pins 1 and 2 which are the inverting and non-inverting error amplifier connections.

Q3, shown as a 2N4033 or MPSA56, is not drawn particularly well, having no emitter arrow. The emitter goes to +12V.

The switching frequency is a little low, 44 kHz, but it could be raised or sync'd to Fsample.

I think they mean that U19 pins 13 and 14 should float, not U19.

SG3524 Block Diagram


SG3524 Block Diagram

ST SG3524 Datasheet

There's also a HV power supply using a 555 timer here: https://www.proaudiodesignforum.com/for ... f=12&t=426

[mediatechnology]

A Phantom Boost Converter using the TI TPS61170 with a voltage doubler output.


48V Phantom Power From A 4.5 to 15V Input Supply Using the TPS61170 Boost Converter

TPS61170 Data Sheet: www.ti.com/lit/ds/symlink/tps61170.pdf

[mediatechnology]

From the Rolls MX422 comes this phantom supply:


Rolls MX422 Phantom Supply

The V+ connection is from the raw 12-16V battery feed.
Vcc for the oscillator is a second pole on the phantom On/Off switch for each channel.
The schematic doesn't say whether the 4069 inverter is a 4069B or 4069UB.
One is buffered, one isn't.
I suspect it uses the 4069UB which are more common.

Looks like the Rolls Phantom supply may have been inspired somewhat by this Electronic Design April 1, 1975 idea from K.R. Johnson:


High Voltage Power Supply Using A 555 Timer