Current Sensor: ACS755xCB-100
Definitions of Accuracy Characteristics
Sensitivity (Sens):
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 amplifier gain (mV/G). The linear IC amplifier gain is trimmed at the
factory to optimize the sensitivity (mV/A) for the full-scale current of the device.
Noise (V
NOISE
):
The product of the linear IC amplifier gain (mV/G) and the noise
fl
oor for the Allegro Hall effect linear IC (≈1 G).
The noise
fl
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.
Linearity (E
LIN
):
The degree to which the voltage output from the sensor varies in direct proportion to the primary current through its
full-scale amplitude. Nonlinearity in the output can be attributed to the saturation of the
fl
ux concentrator approaching the full-scale
current. The following equation is used to derive the linearity
Nonlinearity (%) = 100
1–
V
out _
3
/
4
full-scale I
P
–V
OUT(Q)
3
V
out _
1
/
4
full-scale I
P
–V
OUT(Q)
where
‰
Vout_¼
full-scale I
P
(V) is the output voltage when the sensed current approximates 0.25
×
I
P(max)
, and
Vout_¾
full-scale I
P
(V) is the output voltage when the sensed current approximates 0.75
×
I
P(max)
.
Quiescent output voltage (V
OUT(Q)
):
The output of the sensor when the primary current is zero. For a unipolar supply voltage, it
nominally remains at 0.6 V. Variation in V
OUT(Q)
can be attributed to the resolution of the Allegro linear IC quiescent voltage trim,
magnetic hysteresis, and thermal drift.
Electrical offset voltage (V
OE
):
The deviation of the device output from its ideal quiescent value due to nonmagnetic causes.
Magnetic offset error (I
ERROM
):
The magnetic offset is due to the residual magnetism (remnant
fi
eld) of the core material. The mag-
netic 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
fl
ux concentrator. The larger mag-
netic offsets are observed at the lower operating temperatures.
Accuracy (E
TOT
):
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:
•
0 A at 25°C:
Accuracy of sensing zero current
fl
ow at 25°C, without the effects of temperature.
•
0 A over temperature:
Accuracy of sensing zero current
fl
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
fl
ow including temperature effects.
4
ACS755100-DS, Rev. 2
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
