ACS715LLCTR-20A-T データシートの表示（PDF） - Allegro MicroSystems

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ACS715LLCTR-20A-T

Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor

Allegro MicroSystems 

ACS715

Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor

with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor

Definitions of Accuracy Characteristics

Sensitivity (Sens). The change in sensor output in response to a

1A 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 pro-

grammed at the factory to optimize the sensitivity (mV/A) for the

full-scale current of the device.

Noise (VNOISE). The product of the linear IC amplifier gain

(mV/G) and the noise floor for the Allegro Hall effect linear IC

(≈1 G). The noise floor 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 (ELIN). 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 flux concentrator approaching

the full-scale current. The following equation is used to derive the

linearity:

{ [ 100 1– Δ gain × % sat ( VIOUT_full-scale amperes – VIOUT(Q))

2 (VIOUT_half-scale amperes – VIOUT(Q) )

where VIOUT_full-scale amperes = the output voltage (V) when the

sensed current approximates full-scale ±IP .

Quiescent output voltage (VIOUT(Q)). The output of the sensor

when the primary current is zero. For a unipolar supply voltage,

it nominally remains at VCC ⁄ 2. Thus, VCC = 5 V translates into

VIOUT(Q) = 2.5 V. Variation in VIOUT(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 out-

put from its ideal quiescent value of VCC / 2 due to nonmagnetic

causes. To convert this voltage to amperes, divide by the device

sensitivity, Sens.

Accuracy (ETOT). The accuracy represents the maximum devia-

tion 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 at right.

Accuracy is divided into four areas:

• 0 A at 25°C. Accuracy of sensing zero current flow at 25°C,

without the effects of temperature.

• 0 A over Δ temperature. Accuracy of sensing zero current

flow 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 flow including temperature effects.

Ratiometry. The ratiometric feature means that its 0 A output,

VIOUT(Q), (nominally equal to VCC/2) and sensitivity, Sens, are

proportional to its supply voltage, VCC . The following formula is

used to derive the ratiometric change in 0 A output voltage,

ΔVIOUT(Q)RAT (%).

VIOUT(Q)VCC / VIOUT(Q)5V

100 

VCC / 5 V



The ratiometric change in sensitivity, ΔSensRAT (%), is defined as:

SensVCC / Sens5V

100

‰  VCC / 5 V

Output Voltage versus Sensed Current

Accuracy at 0 A and at Full-Scale Current

Increasing VIOUT(V)

Accuracy

Over $Temp erature

Accuracy

25°C Only

Average

VIOUT

Accuracy

Over $Temp erature

Accuracy

25°C Only

–IP (A)

30 A

Full Scale

+IP (A)

0A

Decreasing VIOUT(V)

Allegro MicroSystems, Inc.

9

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

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