Download Cobra CPI M1500 Specifications

3.9.3.1 ACS712 Current Sensor
The ACS712 is a very cheap, accurate and easy to implement electric sensor
chip available from Allegro Microsystems. It is a fully integrated current sensor
that gives precise current measurement for both AC and DC signals. The great
precision and accuracy of the sensor is due to factory trimming. The sensor
comes mounted in a PCB board that is nearly the size of a quarter. Because it
comes pre-soldered on a PCB as shown in Figure 25, the sensor can be easily
soldered to other parts in the circuit.
Figure 25 - ACS712 Current Sensor.
Reproduced with permission from Sparkfun Electronics.
The thick copper conductor and the traces allow the device to support up to five
times the amount of current without damaging the unit. The sensor requires a DC
voltage of 5 volts for the VCC in order to operate. As well as with the other
sensors, in order to keep it at an optimal accuracy, the integration of filters is
recommended, so that the noise signals coming from the supplied 5 V do not
impact the current readings from the sensor.
The device bandwidth can be easily set via the “FILTER” pin as shown in Figure
25. The output voltage that is delivered by the sensor is proportional to the AC or
DC current depending on which is being measured. The sensor utilizes a very
precise, low-offset, linear Hall sensor circuit with a copper conduction path
located near the surface of the die. When current is applied through this copper
conduction path, the flow of current generates a magnetic field that is sensed by
the integrated Hall IC and then converts that magnetic field into a proportional
voltage. The accurate readings are achieved in the device by the close proximity
of the magnetic signal to the Hall transducer. The output generated by the sensor
has a positive slope when the current that is flowing through the current sensor
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