Current Sensing for dual rail PSU

Thread Starter

RobinGriffiths

Joined Aug 16, 2011
17
Hi,

I've designed and built a dual rail PSU. I now want to use an Arduino to monitor and control it. The most important feature is to display current supplied by the positive and negative rails. I was planning to use Maxim 437x high side current sense ICs.

Can I use them for both positive and negative rails by simply reversing the shunt inputs R- and R+? Since the Arduino/Maxim grounds are floating with respect to the PSU ground, I guess that would just work? Or would this mean that I'd need a low side current sense IC for the negative rail? This is the type of thing I'm thinking of.

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andrewmm

Joined Feb 25, 2011
572
check the data sheet for what voltage is allowed on the Rs pins with respect to the Vcc.
I'd not expect it to like a negative voltage on the Rs pin.
 

Thread Starter

RobinGriffiths

Joined Aug 16, 2011
17
check the data sheet for what voltage is allowed on the Rs pins with respect to the Vcc.
I'd not expect it to like a negative voltage on the Rs pin.
Hi,

I think the way I've done it, RS+ is positive with respect to RS- for both rails. 0V at the top is floating with repect to Gnd at the bottom, the only 'coupling' between the two cicuits should be via the differentional current sense amplifier, which should have a high input impedance.
 
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schmitt trigger

Joined Jul 12, 2010
320
You did not attach the datasheet for the proposed component, but what the other poster is attempting to tell you, is that the monitored current will be at a voltage below the (floating) ground. Might not be possible but..... Hard to say without the datasheet.
 
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Thread Starter

RobinGriffiths

Joined Aug 16, 2011
17
Thanks for that. Have attached data sheet. Not quite sure what I'm looking for on data sheet, but these three under 'Absolute Maximum Ratings' maybe ?

VCC, RS+, RS- to GND-0.3V to +30V
OUT to GND-0.3V to (VCC + 0.3V)
Differential Input Voltage (VRS+ - VRS- )±8V

Not sure if these are 'the chip won't work but won't blow up' rather than operational range values.
 

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