ACS722KMA View Datasheet(PDF) - Allegro MicroSystems
Part Name
Description
MFG CO.
ACS722KMA
Allegro MicroSystems
'ACS722KMA' PDF : 17 Pages View PDF
ACS722KMA
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
DEFINITIONS OF ACCURACY CHARACTERISTICS
Sensitivity (Sens)
The change in sensor IC output in response to a 1 A change
through the primary conductor. The sensitivity is the product
of the magnetic coupling factor (G / A) (1 G = 0.1 mT)and the
linear IC amplifier gain (mV/G). The linear IC amplifier gain is
programmed at the factory to optimize the sensitivity (mV/A) for
the full-scale current of the device.
Nonlinearity (ELIN)
The nonlinearity is a measure of how linear the output of the sen-
sor IC is over the full current measurement range. The nonlinear-
ity is calculated as:
{ [ ELIN =
1–
VIOUT (IPR(max)) – VIOUT(Q)
2 × VIOUT (IPR(max)/2) – VIOUT(Q)
× 100 (%)
where VIOUT(IPR(max)) is the output of the sensor IC with the
maximum measurement current flowing through it and
VIOUT(IPR(max)/2) is the output of the sensor IC with half of the
maximum measurement current flowing through it.
Zero Current Output Voltage (VIOUT(Q))
The output of the sensor when the primary current is zero. For
a unipolar supply voltage, it nominally remains at 0.5 × VCC for
a bidirectional device and 0.1 × VCC for a unidirectional device.
For example, in the case of a bidirectional output device, VCC =
3.3 V translates into VIOUT(Q) = 1.65 V. Variation in VIOUT(Q) can
be attributed to the resolution of the Allegro linear IC quiescent
voltage trim and thermal drift.
Offset Voltage (VOE)
The deviation of the device output from its ideal quiescent value
of 0.5 × VCC (bidirectional) or 0.1 × VCC (unidirectional) due to
nonmagnetic causes. To convert this voltage to amperes, divide
by the device sensitivity, Sens.
Total Output Error (ETOT)
The the difference between the current measurement from the
sensor IC and the actual current (IP), relative to the actual current.
This is equivalent to the difference between the ideal output volt-
age and the actual output voltage, divided by the ideal sensitivity,
relative to the current flowing through the primary conduction
path:
due to sensitivity error, and at relatively low currents, ETOT will
be mostly due to Offset Voltage (VOE ). In fact, at IP = 0, ETOT
approaches infinity due to the offset. This is illustrated in Figures
1 and 2. Figure 1 shows a distribution of output voltages versus IP
at 25°C and across temperature. Figure 2 shows the correspond-
ing ETOT versus IP .
Increasing
VIOUT (V)
Accuracy Across
Temperature
Accuracy at
25°C Only
Accuracy Across
Temperature
Ideal VIOUT
Accuracy at
25°C Only
IPR(min)
–IP (A)
VIOUT(Q)
+IP (A)
Full Scale IP
IPR(max)
0A
Accuracy at
25°C Only
Accuracy Across
Temperature
Decreasing
VIOUT (V)
Figure 1: Output Voltage versus Sensed Current
+ETOT
Across Temperature
25°C Only
–IP
+IP
ETOT(IP) =
VIOUT_ideal(IP) – VIOUT(IP)
Sensideal(IP) × IP
×
100
(%)
–ETOT
The Total Output Error incorporates all sources of error and is a
function of IP . At relatively high currents, ETOT will be mostly
Figure 2: Total Output Error versus Sensed Current
Allegro MicroSystems, LLC
12
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
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