115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 2003, Allegro MicroSystems, Inc.
Current Sensor: ACS750xCA-100
The change in sensor output in response to a 1 A change through the primary conductor. The sensitivity is the
product of the magnetic circuit sensitivity (G / A) and the linear IC ampli er gain (mV/G). The linear IC ampli er gain is trimmed at the
factory to optimize the sensitivity (mV/A) for the full-scale current of the device.
The product of the linear IC ampli er gain (mV/G) and the noise oor for the Allegro Hall effect linear IC (≈1 G).
The noise oor is derived from the thermal and shot noise observed in Hall elements. Dividing the noise (mV) by the sensitivity (mV/
A) provides the smallest current that the device is able to resolve.
The degree to which the voltage output from the sensor varies in direct proportion to the primary current through
its full-scale amplitude. Linearity reveals the maximum deviation from the ideal transfer curve for this transducer. Nonlinearity in the
output can be attributed to the gain variation across temperature and saturation of the ux concentrator approaching the full-scale cur-
rent. The following equation is used to derive the linearity:
De nitions of Accuracy Characteristics
100 1–
[{
[{
Vout_full-scale amperes –VOUT(Q)
gain % sat ( )
2 (Vout_half-scale amperes –VOUT(Q) )
100
[
[
Vout_+full-scale amperes –VOUT(Q)
VOUT(Q) –Vout_–full-scale amperes
∆ gain = the gain variation as a function of temperature changes from 25ºC,
% sat = the percentage of saturation of the ux concentrator, which becomes signi cant as the current
being sensed approaches full-scale ±I
= the output voltage (V) when the sensed current approximates full-scale ±I
The degree to which the absolute voltage output from the sensor varies in proportion to either a positive or nega-
tive full-scale primary current. The following equation is used to derive symmetry:
Quiescent output voltage (V
The output of the sensor when the primary current is zero. For a unipolar supply voltage, it
can be attributed to the resolution
of the Allegro linear IC quiescent voltage trim, magnetic hysteresis, and thermal drift.
Electrical offset voltage (V
The deviation of the device output from its ideal quiescent value of V
⁄ 2 due to nonmagnetic causes.
CC ⁄ 2 due to nonmagnetic causes.
CC
The magnetic offset is due to the residual magnetism (remnant eld) of the core material. The magnetic
offset error is highest when the magnetic circuit has been saturated, usually when the device has been subjected to a full-scale or high-
current overload condition. The magnetic offset is largely dependent on the material used as a ux concentrator. The larger magnetic
offsets are observed at the lower operating temperatures.
The accuracy represents the maximum deviation of the actual output from its ideal value. This is also known as the
total ouput error. The accuracy is illustrated graphically in the Output Voltage versus Current chart on the following page.
Accuracy is divided into four areas:
Accuracy of sensing zero current ow at 25°C, without the effects of temperature.
Accuracy of sensing zero current ow including temperature effects.
Full-scale current at 25°C:
Accuracy of sensing the full-scale current at 25°C, without the effects of temperature.
Full-scale current over Δ temperature:
Accuracy of sensing full-scale current ow including temperature effects.