Should I go high side or low side for current measurment in my Lab power supply

[Sarvesaa]

Hi guys,

I am building a power supply with a 3055 transistor. With 0-24V output and also with current limiting function.
I prototyped it on a breadbroad and it works fine, the voltage goes all the way down to 0.050V. Good enough I guess.

I want to have a panel showing the output terminal voltage and the current flowing. Also POWER by just multiplying voltage and current in arduino code.

I have a ADS1115 16bit ADC laying around and I want to use it in this project for sensing voltage and current which would be perfect for this project.

I am not sure whether to put the shunt on High side or Low side.

Thank you

With Regards
Sarvesaa Jagan

[Colt45]

I feel like low side is more typical as that's more likely to be in common mode input range of whatever amp you stick on it... though some go to V+ and not V- (TL07x, eg)

[frogblender]

Current has a way of sneakily sneaking back to the source using other ground paths. 

Example:  recently I used a DC clamp meter on a computer's ATX powersupply aux connectors (the cable that powers your GPU):   clamping the positive wires showed 20amps.... but clamping the negative showed 6amps... because some of the return current was sneaking back through the motherboard's ground.

If your power supply is utterly isolated, then this won't be a problem.

[David Hess]

As long as the supply is floating and only grounded at the output terminal, either high or low side sensing can be used.  Often high side sensing is preferred despite any inconvenience because it makes control of a dual bipolar supply easier, like on a Tektronix PS503A power supply which has simultaneous positive and negative outputs.

[SiliconWizard]

Yep. Note the importance of floating.