The Allegro™ ACS722 current sensor IC is an economical and
precise solution for AC or DC current sensing in industrial,
commercial, and communication systems. The small package
is ideal for space constrained applications while also saving
costs due to reduced board area. Typical applications include
motor control, load detection and management, switched-mode
power supplies, and overcurrent fault protection.
The device consists of a precise, low-offset, linear Hall
sensor circuit with a copper conduction path located near the
surface of the die. Applied current flowing through this copper
conduction path generates a magnetic field which is sensed by
the integrated Hall IC and converted into a proportional voltage.
Device accuracy is optimized through the close proximity of the
magnetic field to the Hall transducer. A precise, proportional
voltage is provided by the low-offset, chopper-stabilized
BiCMOS Hall IC, which includes Allegro’s patented digital
temperature compensation, resulting in extremely accurate
performance over temperature. The output of the device has
a positive slope when an increasing current flows through the
primary copper conduction path (from pins 1 through 4, to pins
5 through 8), which is the path used for current sensing. The
internal resistance of this conductive path is 0.85 mΩ typical,
providing low power loss.
The terminals of the conductive path are electrically isolated
from the sensor leads (pins 9 through 16). This allows the
ACS722 current sensor IC to be used in high-side current sense
applications without the use of high-side differential amplifiers
or other costly isolation techniques.
ACS722-DS, Rev 2
MCO-0000540
• Patented integrated digital temperature compensation
circuitry allows for near closed loop accuracy over
temperature in an open loop sensor
• UL60950-1 (ed. 2) certified
□Dielectric Strength Voltage = 4.8 kVrms
□Basic Isolation Working Voltage = 1097 Vrms
□Reinforced Isolation Working Voltage = 565 Vrms
• Industry-leading noise performance with greatly
improved bandwidth through proprietary amplifier and
filter design techniques
• Pin-selectable band width: 80 kHz for high bandwidth
applications or 20 kHz for low noise performance
• 0.85 mΩ primary conductor resistance for low power
loss and high inrush current withstand capability
• Low-profile SOIC16 package suitable for space-
constrained applications
• 3 to 3.6 V, single supply operation
• Output voltage proportional to AC or DC current
• Factory-trimmed sensitivity and quiescent output voltage
for improved accuracy
High Accuracy, Hall-Effect Based Current Sensor
IC in High Isolation SOIC16 Package
Continued on the next page…
PACKAGE: 16-pin SOICW (suffix MA)
Typical Application
1
5
2
6
3
7
4
8
+I
I
C
C
0.1 F
–I
IP+
IP+
IP+
IP+
IP–
IP–
IP–
IP–
P
P
L
BYPASS
P
NC
GND
NC
BW_SEL
VIOUT
NC
VCC
NC 9
10
11
12
13
14
15
16
ACS722 The ACS722 outputs an
analog signal, VIOUT , that
changes, proportionally, with
the bidirectional AC or DC
primary sensed current, IP ,
within the specified measure-
ment range. The BW_SEL pin
can be used to select one of
the two bandwidths to opti-
mize the noise performance.
Grounding the BW_SEL pin
puts the part in the high
bandwidth (80 kHz) mode.
Continued on the next page…
CB Certicate Number:
US-32210-M1-UL
Not to scale
FEATURES AND BENEFITS DESCRIPTION
TÜV America
Certificate Number:
U8V 16 03 54214 040
CB 16 03 54214 039
Type
tested
ACS722KMA
December 14, 2018
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
2
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
The ACS722 is provided in a low profile surface mount SOIC16
package. The leadframe is plated with 100% matte tin, which is
compatible with standard lead (Pb) free printed circuit board assembly
processes. Internally, the device is Pb-free, except for flip-chip high-
temperature Pb-based solder balls, currently exempt from RoHS.
The device is fully calibrated prior to shipment from the factory.
DESCRIPTION (continued)
• Chopper stabilization results in extremely stable quiescent
output voltage
• Nearly zero magnetic hysteresis
• Ratiometric output from supply voltage
FEATURES AND BENEFITS (continued)
SELECTION GUIDE
Part Number IPR (A) Sens(Typ) at VCC = 3.3 V
(mV/A) TA (°C) Packing [1]
ACS722KMATR-10AB-T ±10 132
–40 to 125 Tape and Reel, 3000 pieces per reel
ACS722KMATR-20AB-T ±20 66
ACS722KMATR-40AB-T ±40 33
[1] Contact Allegro for additional packing options.
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
3
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
THERMAL CHARACTERISTICS
Characteristic Symbol Test Conditions* Value Units
Package Thermal Resistance
(Junction to Ambient) RθJA
Mounted on the Allegro 85-0738 evaluation board with 700 mm2 of 4 oz.
copper on each side, connected to pins 1 and 2, and to pins 3 and 4, with
thermal vias connecting the layers. Performance values include the power
consumed by the PCB.
23 ºC/W
Package Thermal Resistance
(Junction to Lead) RθJL Mounted on the Allegro ASEK 722 evaluation board. 5 ºC/W
*Additional thermal information available on the Allegro website.
ISOLATION CHARACTERISTICS
Characteristic Symbol Notes Rating Unit
Dielectric Strength Test Voltage VISO
Agency type-tested for 60 seconds per UL 60950-1
(edition. 2). Production tested at 3000 VRMS for 1 second,
in accordance with UL 60950-1 (edition. 2).
4800 VRMS
Working Voltage for Basic Isolation VWVBI
Maximum approved working voltage for basic (single)
isolation according UL 60950-1 (edition 2)
1550 VPK
1097 VRMS or VDC
Working Voltage for Reinforced Isolation VWVRI
Maximum approved working voltage for reinforced
isolation according to UL 60950-1 (edition 2)
800 VPK
565 VRMS or VDC
Clearance Dcl Minimum distance through air from IP leads to signal
leads. 7.5 mm
Creepage Dcr Minimum distance along package body from IP leads to
signal leads 8.2 mm
ABSOLUTE MAXIMUM RATINGS
Characteristic Symbol Notes Rating Units
Supply Voltage VCC 6 V
Reverse Supply Voltage VRCC –0.1 V
Output Voltage VIOUT 25 V
Reverse Output Voltage VRIOUT –0.1 V
Operating Ambient Temperature TARange K –40 to 125 °C
Junction Temperature TJ(max) 165 °C
Storage Temperature Tstg –65 to 165 °C
SPECIFICATIONS
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
4
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
Dynamic Offset
Cancellation
Master Current
Supply Programming
Control
EEPROM and
Control Logic
Offset
Control
Sensitivity
Control
Tuned
Filter
Temperature
Sensor
Hall
Current
Drive
POR
To All Subcircuits
IP+
IP+
IP+
IP+
IP
IP
IP
–
–
–
IP–
VCC
VIOUT
GND
BW_SEL
Terminal List Table
Number Name Description
1, 2, 3, 4 IP+ Terminals for current being sensed; fused internally
5, 6, 7, 8 IP- Terminals for current being sensed; fused internally
9, 16 NC No internal connection; recommended to be left unconnected in order to
maintain high creepage.
10 VCC Device power supply terminal
11, 14 NC No internal connection; recommened to connect to GND for the best ESD
performance
12 VIOUT Analog output signal
13 BW_SEL Terminal for selecting 20 kHz or 80 kHz bandwidth
15 GND Signal ground terminal
Functional Block Diagram
Pinout Diagram
1
IP+
2
IP+
3
IP+
4
IP+
5
IP-
6
IP-
7
IP-
8
IP- 9 NC
10 VCC
11 NC
12 VIOUT
13 BW_SEL
14 NC
15 GND
16 NC
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
5
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
Characteristic Symbol Test Conditions Min. Typ. Max. Units
Supply Voltage VCC 33.3 3.6 V
Supply Current ICC VCC within VCC(min) and VCC(max) – 9 12 mA
Output Capacitance Load CLVIOUT to GND – – 10 nF
Output Resistive Load RLVIOUT to GND 4.7 – – kΩ
Primary Conductor Resistance RIP TA = 25°C – 0.85 –mΩ
Magnetic Coupling Factor CF–4.5 –G/A
Rise Time tr
IP = IP(max), TA = 25°C, CL = 1 nF,
BW_SEL tied to GND –4–μs
IP = IP(max), TA = 25°C, CL = 1 nF,
BW_SEL tied to VCC –17.5 –μs
Propagation Delay tpd
IP = IP(max), TA = 25°C, CL = 1 nF,
BW_SEL tied to GND –2–μs
IP = IP(max), TA = 25°C, CL = 1 nF,
BW_SEL tied to VCC –5–μs
Response Time tRESPONSE
IP = IP(max), TA = 25°C, CL = 1 nF,
BW_SEL tied to GND –5–μs
IP = IP(max), TA = 25°C, CL = 1 nF,
BW_SEL tied to VCC –22.5 –μs
Internal Bandwidth BWi
Small signal –3 dB; CL = 1 nF,
BW_SEL tied to GND – 80 – kHz
Small signal –3 dB; CL = 1nF,
BW_SEL tied to VCC – 20 – kHz
Noise Density IND Input referenced noise density;
TA = 25°C, CL = 1 nF – 300 – µA(rms)/
√Hz
Noise IN
Input referenced noise; BWi = 80 kHz,
TA = 25°C, CL = 1 nF – 84 – mA(rms)
Input referenced noise; BWi = 20 kHz,
TA = 25°C, CL = 1 nF – 42 – mA(rms)
Nonlinearity ELIN Through full range of IP– ±1 %
Saturation Voltage [2] VOH RL = 4.7 kΩ, TA = 25°C VCC – 0.33 – – V
VOL RL = 4.7 kΩ, TA = 25°C – – 0.33 V
Power-On Time tPO
Output reaches 90% of steady-state
level, TA = 25°C, IP = IPR(max) applied – 64 – μs
[1] Device may be operated at higher primary current levels, IP , ambient temperatures, TA , and internal leadframe temperatures, provided the Maximum Junction Tempera-
ture, TJ(max), is not exceeded.
[2] The sensor IC will continue to respond to current beyond the range of IP until the high or low saturation voltage; however, the nonlinearity in this region will be worse than
through the rest of the measurement range.
COMMON ELECTRICAL CHARACTERISTICS [1]: Valid through the full range of TA = –40°C to 125°C
,
and at VCC
= 3.3 V, unless otherwise specied
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
6
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
xKMATR-10AB PERFORMANCE CHARACTERISTICS: TA Range K, valid at TA = – 40°C to 125°C, VCC = 3.3 V,
unless otherwise specied
Characteristic Symbol Test Conditions Min. Typ.[1] Max. Units
NOMINAL PERFORMANCE
Current Sensing Range IPR –10 – 10 A
Sensitivity Sens IPR(min) < IP < IPR(max) – 132 – mV/A
Zero Current Output Voltage VIOUT(Q) Bidirectional; IP = 0 A – VCC ×
0.5 – V
ACCURACY PERFORMANCE
Total Output Error [2] ETOT
IP = IPR(max), TA = 25°C to 125°C –2.5 ±1.7 2.5 %
IP = IPR(max), TA = –40°C to 25°C – ±2.5 – %
TOTAL OUTPUT ERROR COMPONENTS [3]: ETOT = ESENS + 100 × VOE/(Sens × IP)
Sensitivity Error ESENS
TA = 25°C to 125°C; measured at IP = IPR(max) –2 ±1.5 2 %
TA = –40°C to 25°C; ; measured at IP = IPR(max) –±2.3 – %
Offset Voltage [4] VOE
IP = 0 A; TA = 25°C to 125°C –15 ±7 15 mV
IP = 0 A; TA = -40°C to 25°C – ±20 – mV
LIFETIME DRIFT CHARACTERISTICS
Sensitivity Error Lifetime Drift Esens_drift – ±1 – %
Total Output Error Lifetime Drift Etot_drift – ±1 – %
[1] Typical values with +/- are 3 sigma values.
[2] Percentage of IP
, with IP = IPR(max)
[3] A single part will not have both the maximum/minimum sensitivity error and maximum/minimum o󰀨set voltage, as that would violate the maximum/minimum total output
error specication. Also, 3 sigma distribution values are combined by taking the square root of the sum of the squares. See Application Information section.
[4] O󰀨set Voltage does not incorporate any error due to external magnetic elds. See section: Impact of External Magnetic Fields.
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
7
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
xKMATR-20AB PERFORMANCE CHARACTERISTICS: TA Range K, valid at TA = – 40°C to 125°C, VCC = 3.3 V,
unless otherwise specied
Characteristic Symbol Test Conditions Min. Typ.[1] Max. Units
NOMINAL PERFORMANCE
Current Sensing Range IPR –20 – 20 A
Sensitivity Sens IPR(min) < IP < IPR(max) – 66 – mV/A
Zero Current Output Voltage VIOUT(Q) Bidirectional; IP = 0 A – VCC ×
0.5 – V
ACCURACY PERFORMANCE
Total Output Error [2] ETOT
IP = IPR(max), TA = 25°C to 125°C –2 ±1.2 2 %
IP = IPR(max), TA = –40°C to 25°C – ±2.1 – %
TOTAL OUTPUT ERROR COMPONENTS [3]: ETOT = ESENS + 100 × VOE/(Sens × IP)
Sensitivity Error ESENS
TA = 25°C to 125°C; measured at IP = IPR(max) –1.5 ±0.75 1.5 %
TA = –40°C to 25°C; ; measured at IP = IPR(max) –±1.25 – %
Offset Voltage [4] VOE
IP = 0 A; TA = 25°C to 125°C –10 ±4.5 10 mV
IP = 0 A; TA = -40°C to 25°C – ±10 – mV
LIFETIME DRIFT CHARACTERISTICS
Sensitivity Error Lifetime Drift Esens_drift – ±1 – %
Total Output Error Lifetime Drift Etot_drift – ±1 – %
[1] Typical values with +/- are 3 sigma values.
[2] Percentage of IP
, with IP = IPR(max)
[3] A single part will not have both the maximum/minimum sensitivity error and maximum/minimum o󰀨set voltage, as that would violate the maximum/minimum total output
error specication. Also, 3 sigma distribution values are combined by taking the square root of the sum of the squares. See Application Information section.
[4] O󰀨set Voltage does not incorporate any error due to external magnetic elds. See section: Impact of External Magnetic Fields.
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
8
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
xKMATR-40AB PERFORMANCE CHARACTERISTICS: TA Range K, valid at TA = – 40°C to 125°C, VCC = 3.3 V,
unless otherwise specied
Characteristic Symbol Test Conditions Min. Typ. [1] Max. Units
NOMINAL PERFORMANCE
Current Sensing Range IPR –40 – 40 A
Sensitivity Sens IPR(min) < IP < IPR(max) – 33 – mV/A
Zero Current Output Voltage VIOUT(Q) Bidirectional; IP = 0 A – VCC ×
0.5 – V
ACCURACY PERFORMANCE
Total Output Error [2] ETOT
IP = IPR(max), TA = 25°C to 125°C –2 ±1.25 2 %
IP = IPR(max), TA = –40°C to 25°C – ±2 – %
TOTAL OUTPUT ERROR COMPONENTS [3]: ETOT = ESENS + 100 × VOE/(Sens × IP)
Sensitivity Error ESENS
TA = 25°C to 125°C; measured at IP = IPR(max) –1.5 ±1.2 1.5 %
TA = –40°C to 25°C; ; measured at IP = IPR(max) –±1.75 – %
Offset Voltage [4] VOE
IP = 0 A; TA = 25°C to 125°C –10 ±3 10 mV
IP = 0 A; TA = -40°C to 25°C – ±5 – mV
LIFETIME DRIFT CHARACTERISTICS
Sensitivity Error Lifetime Drift Esens_drift – ±1 – %
Total Output Error Lifetime Drift Etot_drift – ±1 – %
[1] Typical values with +/- are 3 sigma values.
[2] Percentage of IP
, with IP = IPR(max)
[3] A single part will not have both the maximum/minimum sensitivity error and maximum/minimum o󰀨set voltage, as that would violate the maximum/minimum total output
error specication. Also, 3 sigma distribution values are combined by taking the square root of the sum of the squares. See Application Information section.
[4] O󰀨set Voltage does not incorporate any error due to external magnetic elds. See section: Impact of External Magnetic Fields.
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
9
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
CHARACTERISTIC PERFORMANCE
Zero Current Output Voltage vs. Temperature
Offset Voltage vs. Temperature
Sensitivity vs. Temperature
Nonlinearity vs. Temperature Total Error at I vs. Temperature
PR(max)
Sensitivity Error vs. Temperature
25
20
15
10
5
0
-10
-5
-15
-20
Temperature (ºC)
Offset Voltage (mV)
-50 -50
-50
-50
-50
-50
00
0
0
0
0
50 50
50
50
50
50
100 100
100
100
100
100
150 150
150
150
150
150
Temperature (ºC)
1630
1635
1640
1645
1650
1665
1655
1670
1660
1675
V (mV)
IOUT(Q)
Temperature (ºC)
129
130
131
132
133
134
135
136
137
Sensitivity (mV/A)
Temperature (ºC)
Sensitivity Error (%)
-2.00
-1.00
0.00
1.00
2.00
3.00
4.00
Temperature (ºC)
Total Error (%)
-2.00
-1.00
0.00
1.00
2.00
3.00
4.00
Temperature (ºC)
Nonlinearity (%)
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.5
1.0
2.0
+3 Sigma Average -3 Sigma
xKMATR-10AB Key Parameters
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
10
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
Zero Current Output Voltage vs. Temperature
Offset Voltage vs. Temperature
Sensitivity vs. Temperature
Nonlinearity vs. Temperature Total Error at I vs. Temperature
PR(max)
Sensitivity Error vs. Temperature
15
10
5
0
-10
-5
Temperature (ºC)
Offset Voltage (mV)
-50 -50
-50
-50
-50
-50
00
0
0
0
0
50 50
50
50
50
50
100 100
100
100
100
100
150 150
150
150
150
150
Temperature (ºC)
1640
1645
1650
1660
1655
1665
V (mV)
IOUT(Q)
Temperature (ºC)
65
65
66
66
67
67
68
68
Sensitivity (mV/A)
Temperature (ºC)
Sensitivity Error (%)
-2.0
-1.0
-1.5
0.0
0.5
0.5
1.5
1.0
2.0
2.5
Temperature (ºC)
Total Error (%)
-2.0
-1.0
-1.5
0.0
-0.5
0.5
1.0
2.0
1.5
3.0
2.5
Temperature (ºC)
Nonlinearity (%)
-1.0
-0.8
-0.6
-0.2
-0.4
0.0
0.2
0.4
0.8
0.6
1.0
+3 Sigma Average -3 Sigma
xKMATR-20AB Key Parameters
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
11
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
Zero Current Output Voltage vs. Temperature
Offset Voltage vs. Temperature
Sensitivity vs. Temperature
Nonlinearity vs. Temperature Total Error at I vs. Temperature
PR(max)
Sensitivity Error vs. Temperature
6
4
2
0
-2
-4
-6
Temperature (ºC)
Offset Voltage (mV)
-50 -50
-50
-50
-50
-50
00
0
0
0
0
50 50
50
50
50
50
100 100
100
100
100
100
150 150
150
150
150
150
Temperature (ºC)
1644
1646
1648
1650
1654
1652
1656
V (mV)
IOUT(Q)
Temperature (ºC)
32
33
33
33
33
33
34
34
Sensitivity (mV/A)
Temperature (ºC)
Sensitivity Error (%)
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
Temperature (ºC)
Total Error (%)
Temperature (ºC)
Nonlinearity (%)
-1.0 -2.5
-0.8 -2.0
-0.6 -1.5
-0.4 -1.0
-0.2 -0.5
0.0 0.0
0.2 0.5
0.8 2.0
0.6 1.5
0.4 1.0
1.0 2.5
+3 Sigma Average -3 Sigma
xKMATR-40AB Key Parameters
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
12
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
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:
1–
[{
[{
VIOUT
(IPR(max)) – VIOUT(Q) × 100 (%)
ELIN = 2 × VIOUT
(IPR(max)/2) – VIOUT(Q)
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:
E
TOT
(I
P
)
V
IOUT_ideal
(I
P
) – V
IOUT
(I
P
)
Sens
ideal
(I
P
)
×
I
P
×
100 (%)=
The Total Output Error incorporates all sources of error and is a
function of IP . At relatively high currents, ETOT will be mostly
DEFINITIONS OF ACCURACY CHARACTERISTICS
Figure 1: Output Voltage versus Sensed Current
Figure 2: Total Output Error versus Sensed Current
0 A
Decreasing
VIOUT (V)
Accuracy Across
Temperature
Accuracy Across
Temperature
Accuracy Across
Temperature
Accuracy at
25°C Only
Accuracy at
25°C Only
Accuracy at
25°C Only
Increasing
VIOUT (V)
Ideal VIOUT
IPR(min)
IPR(max)
+IP (A)
–IP (A)
VIOUT(Q)
Full Scale IP
+IP
–IP
+ETOT
–ETOT
Across Temperature
25°C Only
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 .
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
13
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
APPLICATION INFORMATION
Impact of External Magnetic Fields
The ACS722 works by sensing the magnetic field created by the
current flowing through the package. However, the sensor cannot
differentiate between fields created by the current flow and exter-
nal magnetic fields. This means that external magnetic fields can
cause errors in the output of the sensor. Magnetic fields which are
perpendicular to the surface of the package affect the output of
the sensor, as it only senses fields in that one plane. The error in
Amperes can be quantified as:
Error(B) =
B
CF
where B is the strength of the external field perpendicular to the
surface of the package in Gauss, and CF is the coupling factor in
G/A. Then, multiplying by the sensitivity of the part (Sens) gives
the error in mV.
For example, an external field of 1 Gauss will result in around
0.22 A of error. If the ACS722KMATR-10AB, which has a nomi-
nal sensitivity of 132 mV/A, is being used, that equates to 29 mV
of error on the output of the sensor.
Table 1: External Magnetic Field (Gauss) Impact
External Field
(Gauss) Error (A) Error (mV)
10AB 20AB 40AB
0.5 0.11 15 7 4
10.22 29 15 7
20.44 58 29 15
Estimating Total Error vs. Sensed Current
The Performance Characteristics tables give distribution (±3
sigma) values for Total Error at I_PR(max); however, one often
wants to know what error to expect at a particular current. This
can be estimated by using the distribution data for the compo-
nents of Total Error, Sensitivity Error and Offset Voltage. The
±3 sigma value for Total Error (ETOT) as a function of the sensed
current (IP) is estimated as:
E(I) =
TOTP
100 × VOE
Sens × IP
E+
SENS
2()
2
Here, ESENS and VOE are the ±3 sigma values for those error
terms. If there is an average sensitivity error or average offset
voltage, then the average Total Error is estimated as:
Sens × IP
E(I) = E+
TOTP SENS
AVGAVG
100 × V
OEAVG
The resulting total error will be a sum of ETOT and ETOT_AVG.
Using these equations and the 3 sigma distributions for Sensitiv-
ity Error and Offset Voltage, the Total Error vs. sensed current
(IP) is below for the ACS722KMATR-40AB. As expected, as one
goes towards zero current, the error in percent goes towards infin-
ity due to division by zero (refer to Figure 3)
15.00
10.00
5.00
0.00
-5.00
-10.00
-15.00
051015202530 35 40
-40C+3sig
-40C-3sig
25C+3sig
25C-3sig
125C+3sig
125C-3sig
Current (A)
Total Error (% of current measured)
Figure 3: Predicted Total Error as a Function of Sensed
Current for the ACS722KMATR-40AB
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
14
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
DEFINITIONS OF DYNAMIC RESPONSE CHARACTERISTICS
Power-On Time (tPO)
When the supply is ramped to its operating voltage, the device
requires a finite time to power its internal components before
responding to an input magnetic field.
Power-On Time (tPO) is defined as the time it takes for the output
voltage to settle within ±10% of its steady state value under an
applied magnetic field, after the power supply has reached its
minimum specified operating voltage (VCC(min)) as shown in the
chart at right (refer to Figure 4).
Rise Time (tr)
The time interval between: a) when the sensor IC reaches 10%
of its full scale value; and b) when it reaches 90% of its full scale
value (refer to Figure 5). The rise time to a step response is used
to derive the bandwidth of the current sensor IC, in which ƒ(–3
dB) = 0.35 / tr. Both tr and tRESPONSE are detrimentally affected by
eddy current losses observed in the conductive IC ground plane.
Propagation Delay (tpd
)
The propagation delay is measured as the time interval between:
a) when the primary current signal reaches 20% of its final value;
and b) when the device reaches 20% of its output corresponding
to the applied current (refer to Figure 5).
Response Time (tRESPONSE)
The time interval between: a) when the primary current signal
reaches 90% of its final value; and b) when the device reaches
90% of its output corresponding to the applied current (refer to
Figure 6).
VIOUT
V
t
VCC
VCC(min.)
90% VIOUT
0
t1= time at which power supply reaches
minimum specified operating voltage
t2=
time at which output voltage settles
within ±10% of its steady state value
under an applied magnetic field
t1t2
tPO
V
CC
(typ.)
Primary Current
VIOUT
90
0
(%)
Response Time, tRESPONSE
t
Primary Current
VIOUT
90
10
20
0
(%)
Propagation Delay, tpd
Rise Time, tr
t
Figure 4: Power-On Time
Figure 5: Rise Time and Propagation Delay
Figure 6: Response Time
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
15
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
7.25
2.25
3.56
1.27
1.27
0.65
15.75
9.54
17.27
21.51
Package Outline
Slot in PCB to maintain >8 mm creepage
once part is on PCB
Current
In
Current
Out
Perimeter holes for stitching to the other,
matching current trace design, layers of
the PCB for enhanced thermal capability.
NOT TO SCALE
All dimensions in millimeters.
Figure 7: High-Isolation PCB Layout
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
16
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
Figure 8: Package MA, 16-pin SOICW
PACKAGE OUTLINE DRAWING
For Reference Only – Not for Tooling Use
(Reference MS-013AA)
NOTTO SCALE
Dimensions in millimeters
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
C
1.27 BSC
A
B
C
B
21
1
16
Branding scale and appearance at supplier discretion
C
SEATING
PLANE
C0.10
16X
0.25 BSC
1.40 REF
2.65 MAX
10.30 ±0.20
7.50 ±0.10 10.30 ±0.33
0.51
0.31
0.30
0.10
0.33
0.20
1.27
0.40
8°
0°
A
Standard Branding Reference View
Branded Face
SEATING PLANE
GAUGE PLANE
NNNNNNN
LLLLLLLL
= Device part number
= Assembly Lot Number, first eight characters
N
L
Terminal #1 mark area
C
2
1
16
0.65 1.27
9.50
2.25
PCB Layout Reference View
Reference land pattern layout (reference IPC7351 SOIC127P600X175-8M);
all pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary
to meet application process requirements and PCB layout tolerances
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
17
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
For the latest version of this document, visit our website:
www.allegromicro.com
REVISION HISTORY
Number Date Description
–March 4, 2015 Initial release
1April 13, 2016 Corrected Package Outline Drawing branding information (page 16).
2December 14, 2018 Updated certificate numbers and minor editorial updates
Copyright ©2018, Allegro MicroSystems, LLC
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permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that
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