Data Sheet

Hall Effect Linear Current Sensor with Overcurrent
Fault Output for < 100 V Isolation Applications
ACS711
11
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
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pro-
grammed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)
andthenoisefloorfortheAllegroHalleffectlinearIC.Thenoise
floorisderivedfromthethermalandshotnoiseobservedinHall
elements.Dividingthenoise(mV)bythesensitivity(mV/A)pro-
vides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fluxconcentratorapproaching
thefull-scalecurrent.Thefollowingequationisusedtoderivethe
linearity:
100
1–
[{
[{
V
IOUT_full-scale amperes
– V
IOUT(Q)
∆ gain × % sat (
)
2 (V
IOUT_half-scale amperes
– V
IOUT(Q)
)
whereV
IOUT_full-scaleamperes
=theoutputvoltage(V)whenthe
sensedcurrentapproximatesfull-scale±I
P
.
Symmetry (E
SYM
). Thedegreetowhichtheabsolutevoltage
outputfromthesensorvariesinproportiontoeitherapositive
ornegativefull-scaleprimarycurrent.Thefollowingformulais
usedtoderivesymmetry:
100
V
IOUT_+ full-scale amperes
– V
IOUT(Q)
V
IOUT(Q)
– V
IOUT_–full-scale amperes

Quiescent output voltage (V
IOUT(Q)
). Theoutputofthesensor
whentheprimarycurrentiszero.Foraunipolarsupplyvoltage,
it

nominallyremainsatV
CC
⁄2.Thus,V
CC
=3.3Vtranslates
intoV
IOUT(Q)
=1.65V.VariationinV
IOUT(Q)
canbeattributedto
theresolutionoftheAllegrolinearICquiescentvoltagetrimand
thermaldrift.
Electrical offset voltage (V
OE
). Thedeviationofthedeviceout-
putfromitsidealquiescentvalueofV
CC
/2duetononmagnetic
causes.Toconvertthisvoltagetoamperes,dividebythedevice
sensitivity,Sens.
Accuracy (E
TOT
). 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below.
Ratiometry.Theratiometricfeaturemeansthatits0Aoutput,
V
IOUT(Q)
,(nominallyequaltoV
CC
/2)andsensitivity,Sens,are
proportionaltoitssupplyvoltage,V
CC
.Thefollowingformulais
usedtoderivetheratiometricchangein0Aoutputvoltage,
ΔV
IOUT(Q)RAT
(%):
Theratiometricchangeinsensitivity,ΔSens
RAT
(%),isdefinedas:
Definitions of Accuracy Characteristics
100
V
IOUT(Q)VCC
/ V
IOUT(Q)3.3V
V
CC
/
3.3 V

100
Sens
VCC
/ Sens
3.3V
V
CC
/
3.3 V

Output Voltage versus Sensed Current
Accuracy at 0 A and at Full-Scale Current
Increasing V
IOUT
(V)
+I
P
(A)
Accuracy
Accuracy
Accuracy
25°C Only
Accuracy
25°C Only
Accuracy
25°C Only
Accuracy
0 A
v rO e ∆Temp erature
Average
V
IOUT
–I
P
(A)
v rO e ∆Temp erature
v rO e ∆Temp erature
Decreasing V
IOUT
(V)
I
P
(min)
I
P
(max)
Full Scale