Prevent 3V LDO heating on 16V rail

[Lou Yates]

Regarding my prototyped circuit:

I presently have a 16VDC supply connected to power op amps. A 3VDC
rail is needed at 100mA for an on-board microporcessor.

I am using a TO-92, 3V LDO regulator. It gets hot, which is doubly bad
since this is a battery powered circuit.

What is the preferred method to make available these two voltages,
with minimum loss in heat and curent?

Thank you for any suggestions.

Lou Yates

 

[Reinardt Behm]

Regarding my prototyped circuit:

I presently have a 16VDC supply connected to power op amps. A 3VDC
rail is needed at 100mA for an on-board microporcessor.

I am using a TO-92, 3V LDO regulator. It gets hot, which is doubly bad
since this is a battery powered circuit.

What is the preferred method to make available these two voltages,
with minimum loss in heat and curent?

Thank you for any suggestions.

Lou Yates

You are burning 16V-3V @ 100mA -> 1.3W. That's why it is getting hot. LDO
means "Low Drop Out" but that just means it can work with a low difference
between input and output, but you have 13V difference.

Use a switching regulator. For that requirements 16V in, 3V out, 100mA there
are hundreds.

 

[Jamie]

Regarding my prototyped circuit:

I presently have a 16VDC supply connected to power op amps. A 3VDC
rail is needed at 100mA for an on-board microporcessor.

I am using a TO-92, 3V LDO regulator. It gets hot, which is doubly bad
since this is a battery powered circuit.

What is the preferred method to make available these two voltages,
with minimum loss in heat and curent?

Thank you for any suggestions.

Lou Yates

do you have board space for this?

http://www.national.com/pf/LM/LM5010.html#Overview

http://www.datasheetcatalog.org/datasheet/irf/om9571-2sp.pdf

http://www.linear.com/product/LT1676

Take your pick, if you don't have room on an exiting board, you
can always put a vertical board in there with 3 stabs to use existing
To-92 holes.
But a switching buck is a good place to start.

The incoming voltage is too high, too much R in the reg and it's
heating up. a switching regulator would work out nicely for you

 

[Spehro Pefhany]

Regarding my prototyped circuit:

I presently have a 16VDC supply connected to power op amps. A 3VDC
rail is needed at 100mA for an on-board microporcessor.

I am using a TO-92, 3V LDO regulator. It gets hot, which is doubly bad
since this is a battery powered circuit.

What is the preferred method to make available these two voltages,
with minimum loss in heat and curent?

Thank you for any suggestions.

Lou Yates

You could try an inexpensive switcher like this one:
http://aosmd.com/res/data_sheets/AOZ1280CI.pdf

Of course it will create some noise that could get into your analog
circuitry.


Best regards,
Spehro Pefhany

 

[Rich Webb]

Regarding my prototyped circuit:

I presently have a 16VDC supply connected to power op amps. A 3VDC
rail is needed at 100mA for an on-board microporcessor.

I am using a TO-92, 3V LDO regulator. It gets hot, which is doubly bad
since this is a battery powered circuit.

What is the preferred method to make available these two voltages,
with minimum loss in heat and curent?

As Reinhardt says, a switching regulator is what you need. The simplest
solution is probably a drop-in all-in-one unit like the 7803SR from
Murata. Note that it is a TO-220 form-factor, not TO-92. Should work
fine with that input voltage and output current.