Alternative Means of Measuring Current

[DigiTan]

I'm looking for a new way to measure currents (0.1mA to 500mA, for 1.7VDC - 12VDC supply rails or thereabout) for a couple projects. I think we're fairly accustomed to the "sensing resistor" method of placing a small-valued resistance in line with the load and measuring the voltage drop across it. And I've seen a few hall-type sensors exploit the Hall effect as well. So I have two questions:

1. Generally speaking, would Hall effect sensing have functional advantages over the Rsense method. (Efficiency? Low Drift? Low Threshold? etc...)

2. Are there other DC current-measuring methods I left out? This current is meant to go into an A/D converter or ucontroller.

 

[MikeMl]

Hall sensors introduce no additional voltage drop, nor break the wire being sensed. Hall sensors are usually used for currents greater than a few A. They have fairly high drift (require zeroing).

Are you familiar with the various high-side and low-side current sensing ICs that are out there?

 

[crutschow]

Hall sensors may also require calibration to get the accuracy you need.

 

[Mikebits]

Hall sensors introduce no additional voltage drop, nor break the wire being sensed. Hall sensors are usually used for currents greater than a few A. They have fairly high drift (require zeroing).

Are you familiar with the various high-side and low-side current sensing ICs that are out there?

Speaking of, I just came across this Isense IC. https://www.electro-tech-online.com/custompdfs/2010/12/LM3812.pdf
There is an app for the part in the EDN design ideas. **broken link removed**

I can't remember which post it was in but Boncuk posted a good Isense part. Maybe he will repost the link.

 

[3v0]

That seems to be an obsolete part.

 

[Mikebits]

That seems to be an obsolete part.

It's an 05 data sheet ?

 

[3v0]

I could not find where one could buy it in reasonable quantities.

**broken link removed**

**broken link removed****broken link removed**

12/1998 Precision Current Gauge IC with Ultra-Low Loss Sense Element and PWM Output, for High-Side Sensing [Obsolete]

 

[Mikebits]

Okay I am convinced. Scratch LM3812 from list.

 

[RCinFLA]

One big advantange of hall effect current measurement is isolation.

There are open loop and closed loop sensors for mid to high current sensors. Closed loop have an op amp that feeds a counter field generating coil on the sense torroid core. It drives the field to near zero which removes much of the magnetic non-linearity of the sense torroid core material.

 

[DigiTan]

It sounds like some kind of high-side current gauge like the LM3812 would do the trick. Depending on their calibration/zeroing needs I might also look into Halls closer, but I like the sound of these current gauge ICs.

 

[Mikebits]

Take a look at this site.
**broken link removed**