ACS722KMA Datasheet

ACS722KMA
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
DESCRIPTION
FEATURES AND BENEFITS
• 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 spaceconstrained 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
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.
Continued on the next page…
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TÜV America
Certificate Number:
U8V 14 11 54214 030
CB 14 11 54214 029
CB Certificate Number:
US-22339-A1-UL
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.
Package: 16-pin SOICW (suffix MA)
Continued on the next page…
Approximate Scale 1:1
+IP
1
IP+
2
IP+
3
IP+
4
IP+
ACS722
NC
GND
NC
BW_SEL
IP
VIOUT
–IP
5
IP–
6
IP–
7
IP–
8
IP–
NC
VCC
NC
16
15
14
13
12
11
10
9
Typical Application
ACS722-DS
CL
C BYPASS
0.1 F
The ACS722 outputs an
analog signal, VIOUT , that
changes, proportionally, with
the bidirectional AC or DC
primary sensed current, IP ,
within the specified measurement range. The BW_SEL pin
can be used to select one of
the two bandwidths to optimize the noise performance.
Grounding the BW_SEL pin
puts the part in the high
bandwidth (80 kHz) mode.
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
Features and Benefits (continued)
• Chopper stabilization results in extremely stable quiescent
output voltage
• Nearly zero magnetic hysteresis
• Ratiometric output from supply voltage
Description (continued)
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 hightemperature Pb-based solder balls, currently exempt from RoHS.
The device is fully calibrated prior to shipment from the factory.
Selection Guide
Part Number
IPR (A)
Sens(Typ) at VCC = 3.3 V
(mV/A)
ACS722KMATR-10AB-T
±10
132
ACS722KMATR-20AB-T
±20
66
ACS722KMATR-40AB-T
±40
33
1Contact Allegro
TA (°C)
Packing1
-40 to 125
Tape and Reel, 3000 pieces per reel
for additional packing options.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
ACS722KMA
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
SPECIFICATIONS
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
TA
–40 to 125
°C
Junction Temperature
TJ(max)
Range K
165
°C
Storage Temperature
Tstg
–65 to 165
°C
Isolation Characteristics
Characteristic
Symbol
Dielectric Strength Test Voltage
VISO
Notes
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).
Working Voltage for Basic Isolation
VWVBI
Maximum approved working voltage for basic (single)
isolation according UL 60950-1 (edition 2)
Working Voltage for Reinforced Isolation
VWVRI
Maximum approved working voltage for reinforced
isolation according to UL 60950-1 (edition 2)
Rating
Unit
4800
VRMS
1550
VPK
1097
VRMS or VDC
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
Thermal Characteristics
Characteristic
Symbol
Test Conditions*
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.
Package Thermal Resistance
(Junction to Lead)
RθJL
Mounted on the Allegro ASEK 722 evaluation board.
Value
Units
23
ºC/W
5
ºC/W
*Additional thermal information available on the Allegro website.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
ACS722KMA
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
VCC
Master Current
Supply
To All Subcircuits
Programming
Control
POR
Hall
Current
Drive
Temperature
Sensor
EEPROM and
Control Logic
Offset
Control
IP+
IP+
IP+
IP+
Dynamic Offset
Cancellation
Sensitivity
Control
IP –
IP –
IP –
IP–
Tuned
Filter
BW_SEL
VIOUT
GND
Functional Block Diagram
IP+ 1
16 NC
IP+ 2
15 GND
IP+ 3
14 NC
IP+ 4
13 BW_SEL
IP-
12 VIOUT
5
IP-
6
11 NC
IP-
7
10 VCC
IP-
8
9 NC
Pin-out Diagram
Terminal List Table
Number
Name
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
11, 14
NC
12
VIOUT
13
BW_SEL
15
GND
Description
Device power supply terminal
No internal connection; recommened to connect to GND for the best ESD
performance
Analog output signal
Terminal for selecting 20 kHz or 80 kHz bandwidth
Signal ground terminal
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
ACS722KMA
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
COMMON ELECTRICAL CHARACTERISTICS1: valid through the full range of TA = –40°C to 125°C , and at VCC =
3.3 V; unless otherwise specified
Characteristic
Symbol
Supply Voltage
VCC
Supply Current
ICC
Output Capacitance Load
CL
Test Conditions
Min.
Typ.
Max.
Units
3
3.3
3.6
V
VCC within VCC(min) and VCC(max)
–
9
12
mA
VIOUT to GND
–
–
10
nF
4.7
–
–
kΩ
–
0.85
–
mΩ
Output Resistive Load
RL
VIOUT to GND
Primary Conductor Resistance
RIP
TA = 25°C
Magnetic Coupling Factor
CF
Rise Time
Propagation Delay
Response Time
Internal Bandwidth
Noise Density
Noise
Nonlinearity
Saturation Voltage2
Power-On Time
–
4.5
–
G/A
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
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
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
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
Input referenced noise density;
TA = 25°C, CL = 1 nF
–
300
–
µA(rms)/
√Hz
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)
ELIN
Through full range of IP
–
±1
VOH
RL = 4.7 kΩ, TA = 25°C
VCC –
0.33
–
–
V
VOL
RL = 4.7 kΩ, TA = 25°C
–
–
0.33
V
tPO
Output reaches 90% of steady-state
level, TA = 25°C, IP = IPR(max) applied
–
64
–
μs
tr
tpd
tRESPONSE
BWi
IND
IN
%
1Device
may be operated at higher primary current levels, IP , ambient temperatures, TA , and internal leadframe temperatures, provided the Maximum Junction Temperature, TJ(max), is not exceeded.
2The sensor IC will continue to respond to current beyond the range of I until the high or low saturation voltage; however, the nonlinearity in this region will be worse than
P
through the rest of the measurement range.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
xKMATR-10AB PERFORMANCE CHARACTERISTICS: TA Range K, valid at TA = – 40°C to 125°C, VCC = 3.3 V, unless
otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.1
Max.
Units
Nominal Performance
Current Sensing Range
IPR
–10
–
10
A
Sens
IPR(min) < IP < IPR(max)
–
132
–
mV/A
VIOUT(Q)
Bidirectional; IP = 0 A
–
VCC x
0.5
–
V
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
–
%
–2
±1.5
2
%
Sensitivity
Zero Current Output Voltage
Accuracy Performance
Total Output Error2
ETOT
Total Output Error Components
3:
Sensitivity Error
ESENS
Offset Voltage4
ETOT = ESENS + 100 × VOE/(Sens × IP)
TA = 25°C to 125°C; measured at IP = IPR(max)
TA = –40°C to 25°C; ; measured at IP = IPR(max)
–
±2.3
–
%
IP = 0 A; TA = 25°C to 125°C
–15
±7
15
mV
IP = 0 A; TA = -40°C to 25°C
–
±20
–
mV
Esens_drift
–
±1
–
%
Etot_drift
–
±1
–
%
VOE
Lifetime Drift Characteristics
Sensitivity Error Lifetime Drift
Total Output Error Lifetime
Drift
Typical values with +/- are 3 sigma values.
Percentage of IP , with IP = IPR(max)
part will not have both the maximum/minimum sensitivity error and maximum/minimum offset voltage, as that would violate the maximum/minimum total output
error specification. Also, 3 sigma distribution values are combined by taking the square root of the sum of the squares. See Application Information section.
4 Offset Voltage does not incorporate any error due to external magnetic fields. See section: Impact of External Magnetic Fields.
1
2
3 A single
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
6
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
xKMATR-20AB PERFORMANCE CHARACTERISTICS: TA Range K, valid at TA = – 40°C to 125°C, VCC = 3.3 V, unless
otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.1
Max.
Units
Nominal Performance
Current Sensing Range
IPR
–20
–
20
A
Sens
IPR(min) < IP < IPR(max)
–
66
–
mV/A
VIOUT(Q)
Bidirectional; IP = 0 A
–
VCC x
0.5
–
V
IP = IPR(max), TA = 25°C to 125°C
–2
±1.2
2
%
IP = IPR(max), TA = –40°C to 25°C
–
±2.1
–
%
–1.5
±0.75
1.5
%
Sensitivity
Zero Current Output Voltage
Accuracy Performance
Total Output Error2
ETOT
Total Output Error Components
3:
Sensitivity Error
ESENS
Offset Voltage4
ETOT = ESENS + 100 × VOE/(Sens × IP)
TA = 25°C to 125°C; measured at IP = IPR(max)
TA = –40°C to 25°C; ; measured at IP = IPR(max)
–
±1.25
–
%
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
Esens_drift
–
±1
–
%
Etot_drift
–
±1
–
%
VOE
Lifetime Drift Characteristics
Sensitivity Error Lifetime Drift
Total Output Error Lifetime
Drift
Typical values with +/- are 3 sigma values.
Percentage of IP , with IP = IPR(max)
part will not have both the maximum/minimum sensitivity error and maximum/minimum offset voltage, as that would violate the maximum/minimum total output
error specification. Also, 3 sigma distribution values are combined by taking the square root of the sum of the squares. See Application Information section.
4 Offset Voltage does not incorporate any error due to external magnetic fields. See section: Impact of External Magnetic Fields.
1
2
3 A single
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
7
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
xKMATR-40AB PERFORMANCE CHARACTERISTICS: TA Range K, valid at TA = – 40°C to 125°C, VCC = 3.3 V, unless
otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.1
Max.
Units
Nominal Performance
Current Sensing Range
IPR
–40
–
40
A
Sens
IPR(min) < IP < IPR(max)
–
33
–
mV/A
VIOUT(Q)
Bidirectional; IP = 0 A
–
VCC x
0.5
–
V
IP = IPR(max), TA = 25°C to 125°C
–2
±1.25
2
%
IP = IPR(max), TA = –40°C to 25°C
–
±2
–
%
–1.5
±1.2
1.5
%
Sensitivity
Zero Current Output Voltage
Accuracy Performance
Total Output Error2
ETOT
Total Output Error Components
3:
Sensitivity Error
ESENS
Offset Voltage4
ETOT = ESENS + 100 × VOE/(Sens × IP)
TA = 25°C to 125°C; measured at IP = IPR(max)
TA = –40°C to 25°C; ; measured at IP = IPR(max)
–
±1.75
–
%
IP = 0 A; TA = 25°C to 125°C
–10
±3
10
mV
IP = 0 A; TA = -40°C to 25°C
–
±5
–
mV
Esens_drift
–
±1
–
%
Etot_drift
–
±1
–
%
VOE
Lifetime Drift Characteristics
Sensitivity Error Lifetime Drift
Total Output Error Lifetime
Drift
Typical values with +/- are 3 sigma values.
Percentage of IP , with IP = IPR(max)
part will not have both the maximum/minimum sensitivity error and maximum/minimum offset voltage, as that would violate the maximum/minimum total output
error specification. Also, 3 sigma distribution values are combined by taking the square root of the sum of the squares. See Application Information section.
4 Offset Voltage does not incorporate any error due to external magnetic fields. See section: Impact of External Magnetic Fields.
1
2
3 A single
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
8
ACS722KMA
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
CHARACTERISTIC PERFORMANCE
xKMATR-10AB Key Parameters
Offset Voltage vs. Temperature
1675
25
1670
20
1665
15
Offset Voltage (mV)
VIOUT(Q) (mV)
Zero Current Output Voltage vs. Temperature
1660
1655
1650
1645
10
5
0
-5
1640
-10
1635
-15
1630
-50
-20
0
50
100
150
-50
0
50
Temperature (ºC)
Sensitivity Error vs. Temperature
Sensitivity vs. Temperature
4.00
136
3.00
135
Sensitivity Error (%)
Sensitivity (mV/A)
150
Temperature (ºC)
137
134
133
132
131
2.00
1.00
0.00
-1.00
130
129
-50
100
-2.00
0
50
100
150
-50
0
Temperature (ºC)
50
100
150
Temperature (ºC)
Total Error at IPR(max) vs. Temperature
Nonlinearity vs. Temperature
4.00
2.0
1.5
3.00
Total Error (%)
Nonlinearity (%)
1.0
0.5
0.0
-0.5
2.00
1.00
0.00
-1.0
-1.00
-1.5
-2.00
-2.0
-50
0
50
100
150
-50
Temperature (ºC)
0
50
100
150
Temperature (ºC)
+3 Sigma
Average
-3 Sigma
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
9
ACS722KMA
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
xKMATR-20AB Key Parameters
Offset Voltage vs. Temperature
1665
15
1660
10
Offset Voltage (mV)
VIOUT(Q) (mV)
Zero Current Output Voltage vs. Temperature
1655
1650
0
-5
1645
1640
-50
5
-10
0
50
100
150
-50
0
50
Temperature (ºC)
68
2.0
67
Sensitivity Error (%)
Sensitivity (mV/A)
2.5
67
66
66
65
1.5
1.0
0.5
0.0
0.5
-1.0
-1.5
65
-2.0
0
50
100
150
-50
0
Temperature (ºC)
100
150
Total Error at IPR(max) vs. Temperature
1.0
3.0
0.8
2.5
0.6
2.0
0.4
1.5
Total Error (%)
Nonlinearity (%)
50
Temperature (ºC)
Nonlinearity vs. Temperature
0.2
0.0
-0.2
-0.4
-0.6
-0.8
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
-1.0
-50
150
Sensitivity Error vs. Temperature
Sensitivity vs. Temperature
68
-50
100
Temperature (ºC)
0
50
100
150
-50
Temperature (ºC)
0
50
100
150
Temperature (ºC)
+3 Sigma
Average
-3 Sigma
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
10
ACS722KMA
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
xKMATR-40AB Key Parameters
Offset Voltage vs. Temperature
1656
6
1654
4
Offset Voltage (mV)
VIOUT(Q) (mV)
Zero Current Output Voltage vs. Temperature
1652
1650
1648
1646
0
-2
-4
1644
-50
2
-6
0
50
100
150
-50
0
50
Temperature (ºC)
100
150
Temperature (ºC)
Sensitivity Error vs. Temperature
Sensitivity vs. Temperature
34
2.5
2.0
34
Sensitivity Error (%)
Sensitivity (mV/A)
1.5
33
33
33
33
33
32
-50
1.0
0.5
0.0
-0.5
-1.0
-1.5
-2.0
-2.5
0
50
100
150
-50
0
Temperature (ºC)
2.5
0.8
2.0
0.6
1.5
0.4
1.0
Total Error (%)
Nonlinearity (%)
1.0
0.2
0.0
-0.2
-0.4
0.5
-0.5
-1.0
-1.5
-0.8
-1.0
-2.0
-2.5
50
150
0.0
-0.6
0
100
Total Error at IPR(max) vs. Temperature
Nonlinearity vs. Temperature
-50
50
Temperature (ºC)
100
150
-50
Temperature (ºC)
0
50
100
150
Temperature (ºC)
+3 Sigma
Average
-3 Sigma
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
11
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.
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 corresponding ETOT versus IP .
Increasing
VIOUT (V)
Nonlinearity (ELIN)
The nonlinearity is a measure of how linear the output of the sensor IC is over the full current measurement range. The nonlinearity is calculated as:
{ [
ELIN = 1–
VIOUT (IPR(max)) – VIOUT(Q)
2 × VIOUT (IPR(max)/2) – VIOUT(Q)
[{
Accuracy at
25°C Only
IPR(min)
Full Scale IP
Accuracy at
25°C Only
Decreasing
VIOUT (V)
Accuracy Across
Temperature
Figure 1: Output Voltage versus Sensed Current
+ETOT
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.
Across Temperature
25°C Only
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 voltage and the actual output voltage, divided by the ideal sensitivity,
relative to the current flowing through the primary conduction
path:
VIOUT_ideal(IP) – VIOUT(IP)
Sensideal(IP) × IP
IPR(max)
0A
Offset Voltage (VOE)
ETOT(IP) =
+IP (A)
VIOUT(Q)
–IP (A)
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.
Accuracy at
25°C Only
Ideal VIOUT
Accuracy Across
Temperature
× 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.
Accuracy Across
Temperature
× 100 (%)
The Total Output Error incorporates all sources of error and is a
function of IP . At relatively high currents, ETOT will be mostly
–IP
+IP
–ETOT
Figure 2: Total Output Error versus Sensed Current
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
12
ACS722KMA
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
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 external 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:
B
CF
For example, an external field of 1 Gauss will result in around
0.22 A of error. If the ACS722KMATR-10AB, which has a nominal 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
Error (A)
0.5
0.11
(
Error (mV)
10AB
20AB
40AB
15
7
4
1
0.22
29
15
7
2
0.44
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 components of Total Error, Sensitivity Error and Offset Voltage. The
2
)
100 × VOE
Sens × IP
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:
ETOTAVG (IP) = ESENSAVG +
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.
External Field
(Gauss)
2
ETOT(IP) = ESENS +
100 × VOEAVG
Sens × IP
The resulting total error will be a sum of ETOT and ETOT_AVG.
Using these equations and the 3 sigma distributions for Sensitivity 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 infinity due to division by zero (refer to Figure 3)
15.00
Total Error (% of current measured)
Error(B) =
±3 sigma value for Total Error (ETOT) as a function of the sensed
current (IP) is estimated as:
10.00
-40C+3sig
5.00
-40C-3sig
25C+3sig
0.00
25C-3sig
125C+3sig
-5.00
125C-3sig
-10.00
-15.00
0
5
10
15
20
25
30
35
40
Current (A)
Figure 3: Predicted Total Error as a Function of Sensed
Current for the ACS722KMATR-40AB
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
13
ACS722KMA
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
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).
V
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
90% VIOUT
VCC(min.)
t1
t2
tPO
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
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.
VCC
VCC(typ.)
0
t
Figure 4: Power-On Time
(%)
90
Primary Current
VIOUT
Rise Time, tr
20
10
0
Propagation Delay, tpd
t
Figure 5: Rise Time and Propagation Delay
(%)
90
Primary Current
VIOUT
Response Time, tRESPONSE
0
t
Figure 6: Response Time
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
14
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
NOT TO SCALE
All dimensions in millimeters.
15.75
9.54
0.65
1.27
Package Outline
Slot in PCB to maintain >8 mm creepage
once part is on PCB
2.25
7.25
1.27
3.56
17.27
Current
Out
Current
In
21.51
Perimeter holes for stitching to the other,
matching current trace design, layers of
the PCB for enhanced thermal capability.
Figure 7: High-Isolation PCB Layout
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
15
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
PACKAGE OUTLINE DRAWING
For Reference Only – Not for Tooling Use
(Reference MS-013AA)
NOT TO 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
8°
0°
10.30 ±0.20
16
0.33
0.20
7.50 ±0.10
10.30 ±0.33
A
1
1.27 1.40 REF
0.40
2
Branded Face
0.25 BSC
SEATING PLANE
16X
C
2.65 MAX
0.10
C
GAUGE PLANE
SEATING
PLANE
0.30
0.10
1.27 BSC
0.51
0.31
0.65
1.27
16
NNNNNNNNNNNN
YYWW
LLLLLLLLLLLL
2.25
1
9.50
1
C
2
PCB Layout Reference View
B
Standard Branding Reference View
N = Device part number
= Supplier emblem
Y = Last two digits of year of manufacture
W = Week of manufacture
L = Lot number
A
Terminal #1 mark area
B
Branding scale and appearance at supplier discretion
C 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
Figure 8: Package MA, 16-pin SOICW
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
16
High Accuracy, Hall-effect Based Current Sensor
IC in High Isolation SOIC16 Package
ACS722KMA
Document Revision History
Revision
Date
–
March 4, 2015
Change
Initial release
Copyright ©2011-2015, Allegro MicroSystems, LLC
Allegro MicroSystems, LLC reserves the right to make, from time to time, such departures from the detail specifications as may be required to
permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that
the information being relied upon is current.
Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of
Allegro’s product can reasonably be expected to cause bodily harm.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, LLC assumes no responsibility for its
use; nor for any infringement of patents or other rights of third parties which may result from its use.
For the latest version of this document, visit our website:
www.allegromicro.com
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
17
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