Raj made a two part tutorial on how to interface a PIC microcontroller with the ACS712 hall-effect current sensor. The first part covers hall-effect theory and basic operation of the ACS712. The second part covers the actual PIC interface, which is simply reading the output voltage of the sensor.
Sensing and controlling current flow is a fundamental requirement in a wide variety of applications including, over-current protection circuits, battery chargers, switching mode power supplies, digital watt meters, programmable current sources, etc. One of the simplest techniques of sensing current is to place a small value resistance (also known as Shunt resistor) in between the load and the ground and measure the voltage drop across it, which in fact, is proportional to the current flowing through it. Whereas this technique is easy and straightforward to implement, it may not be very precise because the value of the shunt resistor slightly varies with its temperature, which in fact is not constant because of the Joule heating. Besides, this simple technique does not provide an isolation between the load and current sensing unit, which is desirable in applications involving high voltage loads.
There is any alternative?
Alternative to what? A hall-effect sensor is an alternative to a shunt resistor … were you looking for a completely different alternative than those?
Alternative to this particular IC, maybe from another manufacturer.
Good question; now I understand.
Try looking at Mouser; they list 873 products under Hall-Effect Sensors. Data Sheets for those products should have example circuits to get you started. From there, you might learn more by visiting the web sites of Hall-Effect Sensor manufacturers to browse around their Application Notes and more Data Sheets.
http://www.mouser.com/Sensors/Hall-Effect-Magnetic-Sensors/_/N-6g7q4?Ns=Pricing%7c0&FS=True
I already look but nothing like this chip.
What about the Honeywell SS341RT, SS343RT, SS349RT; or the Diodes Inc. AH337-WG-7?
There are just hall-effect sensors, to sense a range of current like the one allegro IC senses you have to “build” a ferrite ring, put an amplifier, etc…. Not exactly the same thing.
Hmm, those Honeywell parts are magnetic sensors, not current sensors. Same with the Diodes Inc. Oops. Looks like you’d have to get rid of the Hall-generator on these parts and use current to generate a variable Hall-Effect. Are there any Hall sensors without the magnetic field generator? I guess the challenge then would be something that is not affected by temperature like a current sense resistor.
Hall-effect sensors are magnetic sensor. they sense the magnetic field.
Right. I mean that it seems like you don’t want to generate a static magnetic field and look for interference, like these switch parts do, but rather that you want the current to generate a proportional magnetic field and sense that as a variable.
it exist LAH-100 current sensor from Liaisons Electroniques-Mécaniques LEM SA. Price unknown, but could be high.