Small Power Supply for Digital Systems?

[Matir]

I'm a software (security) guy just getting into embedded systems (or, as marketing would call it, the "Internet of Things").  Consequently, most of the systems I'm dealing with are operating at either +5V or +3.3V (or some mix of both).  For my home workspace, I don't have much space at all (really just an Ikea desk in my home office) and so I'm thinking "small" for my tools.  Consequently, I'd like to find a small power supply for working on these systems.

At a minimum, I need to support:

• +5V/+3.3V outputs (probably single output is fine)
• Current limiting for when I do stupid things
• ~2A output

Ideally, I'd also like:

• Voltage/current display
• Output on/off switch
• Maybe as high as 12V/3A on occasion

Space and price are premiums, but I don't want to blow up the DUT, so safety/correctness first.

[TheUnnamedNewbie]

Are you looking for a simple fixed supply or a full-on bench supply? If you are looking for the latter, last I heard the entry rigol ones are pretty good. They perform well, and are not that expensive (I think around 400 EUR?)

If you really need simply low power/size, it might be interesting to wire up a handfull of LM7805 or similar with a small transformer. They could fit in really small boxes.

[john_c]

Given that you want to focus on microelectronics, and keeping in mind all your requirements, I'd say you have two options. #1 would be something like a Tekpower TP1803D.

#2 would be a 12V fixed power supply (available as a cheap "brick" at currents up to 5A or even a bit more) plus a small adjustable step-down DC converter. You could also go up to 19V or 24V for the fixed voltage, or use an old laptop power supply for that part. This would be very easy on work space. There are a ton of converters on Ebay. Here's one with an enclosure and a display: http://www.ebay.com/itm/351824924923

[Matir]

The problem with the converters is that they're not current limiting.  I would like to, at some point, design a current-limiting power supply, but I'm not sure I'm at that stage yet.

I'm often supplying power to chips in unusual ways (trying to hold a MCU in reset to read out serial flash, for example) and I'm hoping current limiting will save me from some of my mistakes. 

The TP1803D looks like a not bad option.

[john_c]

There are some DC converters I've seen (mostly step up converters for LEDs) that have a screw-pot adjustable current limit. None that I've seen that also have a display, though.

[ez24]

Given that you want to focus on microelectronics, and keeping in mind all your requirements, I'd say you have two options. #1 would be something like a Tekpower TP1803D.

#2 would be a 12V fixed power supply (available as a cheap "brick" at currents up to 5A or even a bit more) plus a small adjustable step-down DC converter. You could also go up to 19V or 24V for the fixed voltage, or use an old laptop power supply for that part. This would be very easy on work space. There are a ton of converters on Ebay. Here's one with an enclosure and a display: http://www.ebay.com/itm/351824924923

Looks interesting so I ordered one of these

https://www.aliexpress.com/item/New-DPS3003-LCD-Constant-Voltage-volt-current-Step-down-Programmable-control-Supply-Power-module-converter-DP30V3A/32684948592.html?spm=2114.01010208.3.1.0x1hiN&ws_ab_test=searchweb0_0,searchweb201602_5_10152_10065_10151_10130_10068_436_10136_10137_10157_10060_10138_10155_10062_10156_10154_10056_10055_10054_10059_10099_10103_10102_5140020_10096_10147_10052_10053_10142_10107_10050_10051_10084_10083_10080_10082_10081_10178_10110_10111_10112_10113_10114_10181_10183_10182_10078_10079_10073_10070_10123,searchweb201603_1,ppcSwitch_3&btsid=a3f1c547-32aa-45a7-8256-dc62dc78ccf8&algo_expid=9625bc3b-b5ec-466a-8487-88914d7249e1-0&algo_pvid=9625bc3b-b5ec-466a-8487-88914d7249e1

Oh brother - what a link.  I will drive it with a 19v laptop supply

thanks

[rdl]

...
Oh brother - what a link.  I will drive it with a 19v laptop supply
...

Just whack off the ? and everything after it. All that extra stuff is of no benefit to anyone but Aliexpress.

https://www.aliexpress.com/item/New-DPS3003-LCD-Constant-Voltage-volt-current-Step-down-Programmable-control-Supply-Power-module-converter-DP30V3A/32684948592.html

It works for ebay too.