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ACS780XLR Datasheet(PDF) 15 Page - Allegro MicroSystems |
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ACS780XLR Datasheet(HTML) 15 Page - Allegro MicroSystems |
15 / 24 page ![]() High-Precision Linear Hall-Effect-Based Current Sensor IC With 200 µΩ Current Conductor ACS780xLR 15 Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com Definitions of Accuracy Characteristics CHARACTERISTIC DEFINITIONS SENSITIVITY (Sens) The change in device output in response to a 1 A change through the primary conductor. The sensitivity is the product of the mag- neticcircuitsensitivity(G/A)andthelinearICamplifiergain (mV/G).ThelinearICamplifiergainisprogrammedatthefactory to optimize the sensitivity (mV/A) for the half-scale current of the device. NOISE (VNOISE) The noise floor is derived from the thermal and shot noise observed in Hall elements. Dividing the noise (mV) by the sensi- tivity (mV/A) provides the smallest current that the device is able to resolve. NONLINEARITY (ELIN) The ACS770 is designed to provide a linear output in response toarampingcurrent.Considertwocurrentlevels:I1andI2.Ide- ally, the sensitivity of a device is the same for both currents, for a given supply voltage and temperature. Nonlinearity is present when there is a difference between the sensitivities measured at I1 and I2. Nonlinearity is calculated separately for the positive (ELINpos)andnegative(ELINneg)appliedcurrentsasfollows: ELINpos = 100 (%) × {1 – (SensIPOS2/ SensIPOS1) } ELINneg = 100 (%) × {1 – (SensINEG2/ SensINEG1)} where: SensIx = (VIOUT(Ix) – VIOUT(Q))/ Ix and IPOSx and INEGx are positive and negative currents. Then: ELIN=max(ELINpos,ELINneg ) RATIOMETRY The device features a ratiometric output. This means that the quiescent voltage output, VOUTQ, and the magnetic sensitivity, Sens, are proportional to the supply voltage, VCC.The ratiometric change(%)inthequiescentvoltageoutputisdefinedas: VCC 5 V VOUT(Q)(VCC) VOUT(Q)(5V) RatERRVOUT(Q) = × 100 % 1 – ( ) andtheratiometricchange(%)insensitivityisdefinedas: VCC 5 V Sens(VCC) Sens(5V) RatERRSens = × 100 % 1 – ( ) QUIESCENT OUTPUT VOLTAGE (VOUT(Q)) Theoutputofthedevicewhentheprimarycurrentiszero.For bidirectional sensors, it nominally remains at VCC⁄2andforuni- directional sensors at 0.1 × VCC. Thus, VCC = 5 V translates into VOUT(BI) = 2.5 V and VOUT(QU) = 0.5 V. Variation in VOUT(Q)can be attributed to the resolution of the Allegro linear IC quiescent voltage trim and thermal drift. ELECTRICAL OFFSET VOLTAGE (VOE) The deviation of the device output from its ideal quiescent value due to nonmagnetic causes. TOTAL OUTPUT ERROR (ETOT) The maximum deviation of the actual output from its ideal value, also referred to as accuracy, illustrated graphically in the output voltage versus current chart on the following page. ETOTisdividedintofourareas: • 0 A at 25°C. Accuracy at the zero current flow at 25°C, without the effects of temperature. • 0 A over Δ temperature. Accuracy at the zero current flow including temperature effects. • Full-scale current at 25°C. Accuracy at the full-scale current at 25°C, without the effects of temperature. • Full-scale current over Δ temperature. Accuracy at the full- scale current flow including temperature effects. = × 100 (%) ETOT(IP) VIOUT(IP) – VIOUT_IDEAL(IP) SensIDEAL × IP where VIOUT_IDEAL(IP) = VIOUT(Q)+ (SensIDEAL × IP ) |
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