Any experience with voltage regulators (ready to use) ?

[gino1961]

Hi to Everyone
i would like to put together a power solution (+5VDC) for my little SMSL su-1 dac consisting in an off-the-shelf regulated linear power supply (i have already some at hand) followed by a voltage regulator stepping the voltage down from 12 to 5VDC
I wonder if anyone can direct me to a voltage regulator with a great quality/price ratio that could provide little residual ripple
i got tired of smps usb charger ...
Thank you very much indeed

 

[Hayabusa]

So skip the transformer and the rectifier and your are good to go!

 

[gino1961]

hi thank you very much indeed for your kind advice
I was looking for something with a more boutique chip ...
i have already ordered these based on LM317

https://m.media-amazon.com/images/I/511TcYqCMVL._SL1000_.jpg

The problem with LM317 is that noise rejection usually drops at higher frequencies
I understand newer regulators are much better ?

 

[Hayabusa]

hi thank you very much indeed for your kind advice
I was looking for something with a more boutique chip ...
i have already ordered these based on LM317

https://m.media-amazon.com/images/I/511TcYqCMVL._SL1000_.jpg

The problem with LM317 is that noise rejection usually drops at higher frequencies
I understand newer regulators are much better ?

The 7805 is a very old design (70's?) but does the job well..

 

[Hayabusa]

https://www.arrow.com/en/products/l7805cv/stmicroelectronics

 

[fpitas]

With so much voltage drop to work with, you might look at the LT1083, LT1084 or LT1085 voltage regulators.

 

[MCH]

Don't miss this video if you are diy it

 

[Sokel]

Replace the 7805 from the second post with one of these and you're good to go if you want a modern chip (there are others too,just an example)

TPS7A4700-78XXG Ultra Low Noise LDO Voltage Regulator

Discover the Best Low Dropout, Ultra Low Noise Voltage Regulators Trusted by Renowned Authorities such as NASA, NIST, and Scientific Labs. Ensure Precision and Reliability in Your Power Supply Solutions, Best Power Source for your HiFi and HiEnd equipment

www.ldovr.com

 

[gino1961]

With so much voltage drop to work with, you might look at the LT1083, LT1084 or LT1085 voltage regulators.

Hi thank you for the very kind and valuable advice
What would be the optimum input DC voltage to step down to 5 Vdc?
I have a variable voltage DC power supply as well

 

[fpitas]

Hi thank you for the very kind and valuable advice
What would be the optimum input DC voltage to step down to 5 Vdc?
I have a variable voltage DC power supply as well

That depends entirely on the regulator. Most LDOs only need about 1V overhead. Some fixed and adjustable need a few volts for best rejection.

 

[gino1961]

That depends entirely on the regulator. Most LDOs only need about 1V overhead. Some fixed and adjustable need a few volts for best rejection.

Thanks a lot again
These data change completely my mind
Problem is that the very most common voltage is 12 VDC
I understand now that this will put the regulator chip under a heavy stress
This makes the goal more complicate

 

[solderdude]

When you need more current (1A or 1.5A or even 2A) and need with an input range of 7-36V you can use a swicthing regulator. No need for heatsinks and direct drop in for 7805.
Look for TSR1 or TSR1.5 series like the Traco TSR 1-2450.

Or, just lower the input voltage to 6.5V using the TSR 1-2465 and add a low drop low noise voltage reg to 5V after it. Is much more energy efficient too (so no hot parts and no cooling needed)

 

[DVDdoug]

I've used LOTS of LM78xx (and LM340 regulators) over the years...

I don't think I've ever gone-through the heatsink calculations, but I've had them overheat and shut down or just get too-hot-to-touch, which makes me "nervous". And I don't know how much power it can dissipate without a heatsink.

When you need more current (1A or 1.5A or even 2A) and need with an input range of 7-36V you can use a swicthing regulator.

Or even less... The LM78xx is "rated" for 1.5A but that doesn't tell the whole story. At 1A without a heatsink it will overheat and shut down. (It has thermal protection so it's not supposed to burn-up.)

The power dissipated by a linear regulator (power generates heat) is calculated is the Voltage dropped across the regulator X the Current through it. The more voltage you drop, the hotter it gets! With 12V in and 5V out, the regulator is dissipating (wasting) 1.4 times the power/energy going to the load.

I wonder if anyone can direct me to a voltage regulator with a great quality/price ratio that could provide little residual ripple
i got tired of smps usb charger ...

Do you actually have a problem?

BTW - You don't need a "low dropout" regulator when going from 12 to 5V. Low-dropout means you can feed-in close to 5V and it still keeps regulating. The 7805 needs at-least 7V and below that the output may drop below 5V, and since it's no longer regulating properly noise/ripple is more-likely to get-through.

 

[gino1961]

When you need more current (1A or 1.5A or even 2A) and need with an input range of 7-36V you can use a swicthing regulator. No need for heatsinks and direct drop in for 7805.
Look for TSR1 or TSR1.5 series like the Traco TSR 1-2450.

Or, just lower the input voltage to 6.5V using the TSR 1-2465 and add a low drop low noise voltage reg to 5V after it. Is much more energy efficient too (so no hot parts and no cooling needed)

Thanks a lot for the precious advice
I guess the smps solution could be indeed the more straightforward one
I see some Meanwell 5V options on the market
I have seen a Meanwell smps inside a high quality ADDA converter by Apogee
They are quite cheap too
I have just to put one in a case
Ripple should be 80mV peak to peak
Available current is not a problem

https://amzn.eu/d/4FgweDt

I would like to add that I have a little dac SMSL ps100 that is perfect tool to check for noise from a USB power supply like chargers and similar
I have opened it and there is no filtering at all on the 5VDC power line input
Using cheap USB chargers i have at hand the noise is very evident with volume cranked up
I will use it as a noise sniffer for testing some off-the-shelf usb power solutions
Instead a su-1 from the same brand is much better at filtering incoming power supply noise
I have not opened it
Yet

 

[AnalogSteph]

i have already ordered these based on LM317
https://m.media-amazon.com/images/I/511TcYqCMVL._SL1000_.jpg

That looks like a bare minimum circuit. It is probably lacking the ADJ pin capacitor, I hope you can tack one on.

Simple Voltage Regulators Part 1: Noise - [English]

I would also turn around the heatsink if you have the space, heat disspation should be better with the fins sticking out from the board.

 

[gino1961]

That looks like a bare minimum circuit. It is probably lacking the ADJ pin capacitor, I hope you can tack one on.

Simple Voltage Regulators Part 1: Noise - [English]

I would also turn around the heatsink if you have the space, heat disspation should be better with the fins sticking out from the board.

Thank you for the very helpful advice
Given that these boards are cheap could using two in series be a sane Idea? In order to reduce the voltage drop on the regulator
Like from 12 to 9 and then from 9 to 5
They are very cheap Indeed and sold in quantities