Power Consumption LimeSDR USB

I’m about to build up the Luftec enclosure for my new LimeSDR USB.
To power up the fan it’s necessary to use the plug to connect the external power supply.

What’s the typical power consumption of the LimeSDR in this setup?

I have not found some information about this.


I measured the current taken by my LimeSDR USB was around 0.65A. The current taken by my LimeSDR-mini was around 0.2A.

Both were measured using an in-line ‘Hot USB Voltage/Current Tester’ that I got from eBay for about 5 Euro.

Thank you!
I’m looking for an appropriate power supply with as less as possible RF impact and sufficient power.

Just to be on he safe side, I’d get a supply that can output at least 1.5A for the LimeSDR USB.

As for low RF noise, good luck with that. Unless someone can recommend a particular branded low noise switcher, I’d stick with a linear!

I am using a 9000mah 7.4v protected lipo pack on mine. Same for my signal generator.
The power input is rated from 6 to 12v.

This was also my current idea… LiFePO4 pack with sufficient capacity

A 1A 12v linear power supply is as simple as can be. No worries, then.
Hint: Thrift shops for old electronics. They had robust power supplies.
Otherwise, roll your own. I think everyone should have the fun of building something like that.
That way, triple the volume of the average LimeUSB (Original, I guess) enclosure & you are all set.
Schematics are all over the web.


I only have old USB 2.0 Charger Doctor, so I could only test power requirements at USB 2 data throughput rates.

My cabling was configured like this:
USB 3.0 port on computer->USB 2.0 extension cable->USB 2.0 Charger Doctor->USB 3.0 cable->LimeSDR-USB

Here is the firmware, hardware and gateware versions, because I’m guessing that the power required will vary between versions (hopefully future versions using less power when inactive):
[22:17:21] INFO: Connected Control port: LimeSDR-USB FW:4 HW:4 Protocol:1 GW:2.16 Ref Clk: 30.72 MHz

I ran some of the tests a few times because USB 2.0 can be problematic, and I’d only trust the accuracy of the Charger Doctor to one decimal place if I’m totally honest.

900 mA at 5 Volts (4.5 Watts) is the maximum that a USB 3.0 port should be able to supply, I think you are best to assume that is how much power you will need when the device is fully active and actually processing data. Not just plugged in and idle.

no device connected (checking USB port looks nominal with no load)
[0.00 Amps 5.02 Volts ~= 0 watts]
[0.00 Amps 5.02 Volts ~= 0 watts]

LimeSDR USB plugged in no software running (2 solid green LED’s and 1 flashing red/green LED) - an idle board.
[0.81 Amps 4.59 Volts ~= 3.72 Watts]
[0.80 Amps 4.58 Volts ~= 3.66 Watts]

Running “LimeSuiteGUI_20180406_d6bc28”
Highlighted device and clicked on connect (2 solid green LED’s and 1 flashing red/green LED)
Just connected but not doing anything else
[0.81 Amps 4.59 Volts ~= 3.72 Watts]
[0.81 Amps 4.57 Volts ~= 3.70 Watts]

While connected and clicked on “Default” (2 solid green LED’s and 1 flashing green LED)
[0.79 Amps 4.52 Volts ~= 3.57 Watts]
[0.86 Amps 4.55 Volts ~= 3.91 Watts]

I partially ran through the “Loopback test” (1 solid green LED, 1 solid red LED, 1 flashing green LED)
I set the CLKGEN, Frequency control CLK_H (MHz) to 16, which should work with USB 2.0 (~6.023MB/s)
[1.18 Amps 4.43 Volts ~= 5.23 watts]
I set the CLKGEN, Frequency control CLK_H (MHz) to 24, which should work with USB 2.0 (~9.035MB/s)
[1.19 Amps 4.42 Volts ~= 5.26 watts]
I set the CLKGEN, Frequency control CLK_H (MHz) to 32, which should work with USB 2.0 (~12.047MB/s)
[1.19 Amps 4.42 Volts ~= 5.26 watts]
I set the CLKGEN, Frequency control CLK_H (MHz) to 36, which should work with USB 2.0 (~27.099MB/s)
[1.19 Amps 4.42 Volts ~= 5.26 watts]
I set the CLKGEN, Frequency control CLK_H (MHz) to 40, which may work with USB 2.0 (~30.116MB/s)
[1.20 Amps 4.44 Volts ~= 5.33 watts]

Looking at the above numbers, I’m starting to think that my Charger Doctor needs an upgrade to a more accurate device. One that fully supports USB 3 and/or USB-C. It claims to function from 3.5 to 7 Volts and 0 to 3 Amps, if you assume that it is accurate to +/-20% then the above numbers start to look more reasonable. I bought for 0.99 cents from aliexpress so it is not going to be the most accurate device. But it does give a rough feel for the power levels.

It pays to be aware of power supply issues where ground of one may not be the same potential as another.
Also I use mine with a signal generator for tuning antennas, so I also run the signal generator from a battery. It prevents grounding issues.

When I first received my board I fiddled with it for about 2hrs and could not get it to do the quick test or receive a thing. Next day I gave it to my mrs to play with while I was at work and it worked fine for her on her laptop! Turns out my usb port can’t supply enough current to make it work. Since converting to a battery supply I have had no problems.

Thank you for the feedback.
I think I will try a LiFePO4 pack for portability reasons.