ACS725KMA
High-Accuracy, Hall-Effect-Based Current Sensor IC with
Common-Mode Field Rejection in High-Isolation SOIC16 Package
DESCRIPTION
FEATURES AND BENEFITS
• Differential Hall sensing rejects common-mode fields
• 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
• Filter pin allows user to filter output for improved
resolution at lower bandwidth
• 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
Continued on the next page…
pe d
Ty ste
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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 Allegro™ ACS725KMA 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. The current is sensed differentially in order to reject
common-mode fields, improving accuracy in magnetically
noisy environments. The inherent 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
ACS725KMA current sensor IC to be used in high-side current
Package: 16-pin SOICW (suffix MA)
Continued on the next page…
Not to scale
+IP
1
IP+
2
IP+
3
IP+
4
IP+
NC
GND
NC
FILTER
IP
–IP
ACS725KMA
5
IP–
6
IP–
7
IP–
8
IP–
VIOUT
NC
VCC
NC
16
15
14
13
12
11
CL
10
9
CBYPASS
0.1 µF
Typical Application
ACS725KMA-DS, Rev. 1
CF
1 nF
The ACS725KMA outputs
an analog signal, VIOUT , that
changes proportionally with
the bidirectional AC or DC
primary sensed current, IP ,
within the specified measurement range.
The FILTER pin can be used
to decrease the bandwidth in
order to optimize the noise
performance.
High-Accuracy, Hall-Effect-Based Current Sensor IC with
Common-Mode Field Rejection in High-Isolation SOIC16 Package
ACS725KMA
FEATURES AND BENEFITS (continued)
• Factory-trimmed sensitivity and quiescent output voltage for
improved accuracy
• Chopper stabilization results in extremely stable quiescent
output voltage
• Nearly zero magnetic hysteresis
• Ratiometric output from supply voltage
DESCRIPTION (continued)
sense applications without the use of high-side differential amplifiers
or other costly isolation techniques.
The ACS725KMA 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. 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)
ACS725KMATR-20AB-T
±20
66
ACS725KMATR-30AB-T
±30
44
ACS725KMATR-30AU-T
30
88
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
ACS725KMA
High-Accuracy, Hall-Effect-Based Current Sensor IC with
Common-Mode Field Rejection 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
VCC + 0.5
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 to 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*
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 ASEK724 evaluation board.
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
ACS725KMA
High-Accuracy, Hall-Effect-Based Current Sensor IC with
Common-Mode Field Rejection in High-Isolation SOIC16 Package
VCC
VCC
Master Current
Supply
To All Subcircuits
Programming
Control
POR
Hall
Current
Drive
Temperature
Sensor
IP+
IP+
IP+
IP+
CBYPASS
0.1 µF
EEPROM and
Control Logic
Offset
Control
Dynamic Offset
Cancellation
Sensitivity
Control
IP–
IP–
IP–
IP–
+
–
RF(int)
GND
CF
+
–
VIOUT
FILTER
Functional Block Diagram
IP+ 1
16 NC
IP+ 2
15 GND
IP+ 3
14 NC
IP+ 4
13 FILTER
IP-
5
12 VIOUT
IP-
6
11 NC
IP-
7
10 VCC
IP-
8
9 NC
Pinout Diagram
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
11, 14
NC
Device power supply terminal
No internal connection; recommened to connect to GND for the best ESD
performance
12
VIOUT
Analog output signal
13
FILTER
Terminal for external capacitor that sets bandwidth
15
GND
Signal ground terminal
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
ACS725KMA
High-Accuracy, Hall-Effect-Based Current Sensor IC with
Common-Mode Field Rejection in High-Isolation SOIC16 Package
COMMON ELECTRICAL CHARACTERISTICS1: Valid through the full range of TA = –40°C to 125°C and VCC = 3.3 V,
unless otherwise specified
Characteristic
Symbol
Test Conditions
Supply Voltage
VCC
Supply Current
ICC
VCC within VCC(min) and VCC(max)
Output Capacitance Load
CL
Output Resistive Load
RL
RIP
TA = 25°C
Primary Conductor Resistance
Internal Filter Resistance2
Min.
Typ.
Max.
Units
3
3.3
3.6
V
–
10
14
mA
VIOUT to GND
–
–
10
nF
VIOUT to GND
4.7
–
–
kΩ
–
0.85
–
mΩ
–
1.7
–
kΩ
RF(INT)
Primary Hall Coupling Factor
G1
TA = 25°C
–
4.5
–
G/A
Secondary Hall Coupling Factor
G2
TA = 25°C
–
0.5
–
G/A
SensMATCH
TA = 25°C
–
±1
–
%
Difference in offset after a ±40 A pulse
–
150
–
mA
Hall Plate Sensitivity Matching
Hysteresis
IHYS
Rise Time
tr
IP = IP(max), TA = 25°C, CL = 1 nF
–
3
–
μs
tpd
IP = IP(max), TA = 25°C, CL = 1 nF
–
2
–
μs
tRESPONSE
IP = IP(max), TA = 25°C, CL = 1 nF
–
4
–
μs
BW
Small signal –3 dB, CL = 1 nF
–
120
–
kHz
Noise Density
IND
Input-referenced noise density;
TA = 25°C, CL = 1 nF
–
450
–
µARMS/
√Hz
Noise
IN
Input-referenced noise; CF = 4.7 nF,
CL = 1 nF, BW = 18 kHz, TA = 25°C
–
60
–
mARMS
Propagation Delay
Response Time
Internal Bandwidth
Nonlinearity
Saturation Voltage3
Power-On Time
ELIN
Through full range of IP
–
±1
VOH
RL = 4.7 kΩ, TA = 25°C
VCC – 0.3
–
–
%
V
VOL
RL = 4.7 kΩ, TA = 25°C
–
–
0.3
V
tPO
Output reaches 90% of steady-state
level, TA = 25°C, IP = IPR(max) applied
–
80
–
μs
Shorted Output to Ground Current
ISC(GND)
TA = 25°C
–
3.3
–
mA
Shorted Output to VCC Current
ISC(VCC)
TA = 25°C
–
45
–
mA
Device 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.
2R
F(INT) forms an RC circuit via the FILTER pin.
3 The 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.
1
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 with
Common-Mode Field Rejection in High-Isolation SOIC16 Package
ACS725KMA
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
Sensitivity
Zero Current Output Voltage
IPR
–20
–
20
A
Sens
IPR(min) < IP < IPR(max)
–
66
–
mV/A
VIOUT(Q)
Bidirectional; IP = 0 A
–
VCC ×
0.5
–
V
IP = IPR(max), TA = 25°C to 125°C
–2.5
±1
2.5
%
IP = IPR(max), TA = –40°C to 25°C
–
±3
–
%
–2
±1
2
%
ACCURACY PERFORMANCE
Total Output Error2
ETOT
TOTAL OUTPUT ERROR COMPONENTS
Sensitivity Error
Offset Voltage
ESENS
VOE
3:
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)
–
±2.5
–
%
IP = 0 A, TA = 25°C to 125°C
–15
±6
15
mV
IP = 0 A, TA = –40°C to 25°C
–
±17
–
mV
LIFETIME DRIFT CHARACTERISTICS
Sensitivity Error Lifetime Drift
Esens_drift
–
±1
–
%
Total Output Error Lifetime Drift
Etot_drift
–
±1
–
%
Typical values with +/- are 3 sigma values.
Percentage of IP , with IP = IPR(max).
3 A single 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.
1
2
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 with
Common-Mode Field Rejection in High-Isolation SOIC16 Package
ACS725KMA
xKMATR-30AB 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
Sensitivity
Zero Current Output Voltage
IPR
–30
–
30
A
Sens
IPR(min) < IP < IPR(max)
–
44
–
mV/A
VIOUT(Q)
Bidirectional; IP = 0 A
–
VCC ×
0.5
–
V
ACCURACY PERFORMANCE
Total Output Error2
ETOT
TOTAL OUTPUT ERROR COMPONENTS
Sensitivity Error
Offset Voltage
ESENS
VOE
3:
IP = IPR(max), TA = 25°C to 125°C
–2.5
±1
2.5
%
IP = IPR(max), TA = –40°C to 25°C
–
±2.5
–
%
–2
±1
2
%
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)
–
±2.4
–
%
IP = 0 A, TA = 25°C to 125°C
–15
±5
15
mV
IP = 0 A, TA = –40°C to 25°C
–
±11
–
mV
LIFETIME DRIFT CHARACTERISTICS
Sensitivity Error Lifetime Drift
Esens_drift
–
±1
–
%
Total Output Error Lifetime Drift
Etot_drift
–
±1
–
%
Typical values with +/- are 3 sigma values.
Percentage of IP , with IP = IPR(max).
3 A single 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.
1
2
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 with
Common-Mode Field Rejection in High-Isolation SOIC16 Package
ACS725KMA
xKMATR-30AU 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
Sensitivity
Zero Current Output Voltage
IPR
Sens
VIOUT(Q)
0
–
30
A
IPR(min) < IP < IPR(max)
–
88
–
mV/A
Unidirectional; IP = 0 A
–
VCC ×
0.1
–
V
IP = IPR(max), TA = 25°C to 125°C
–2.5
±1.25
2.5
%
IP = IPR(max), TA = –40°C to 25°C
–
±2.5
–
%
–2
±1.2
2
%
ACCURACY PERFORMANCE
Total Output Error2
ETOT
TOTAL OUTPUT ERROR COMPONENTS
Sensitivity Error
Offset Voltage
ESENS
VOE
3:
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)
–
±2.5
–
%
IP = 0 A, TA = 25°C to 125°C
–15
±10
15
mV
IP = 0 A, TA = –40°C to 25°C
–
±18
–
mV
LIFETIME DRIFT CHARACTERISTICS
Sensitivity Error Lifetime Drift
Esens_drift
–
±1
–
%
Total Output Error Lifetime Drift
Etot_drift
–
±1
–
%
Typical values with +/- are 3 sigma values.
Percentage of IP , with IP = IPR(max).
3 A single 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.
1
2
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
8
High-Accuracy, Hall-Effect-Based Current Sensor IC with
Common-Mode Field Rejection in High-Isolation SOIC16 Package
ACS725KMA
CHARACTERISTIC PERFORMANCE
xKMATR-20AB
Zero Current Output Voltage vs. Temperature
Offset Voltage vs. Temperature
20
1665
15
Offset Voltage (mV)
1670
VIOUT(Q) (mV)
1660
1655
1650
1645
1640
1635
1630
10
5
0
-5
-10
-15
-20
1625
-25
-50
0
50
100
150
-50
0
Temperature (°C)
Sensitivity vs. Temperature
150
2.0
67
1.0
Sensitivity Error (%)
Sensitivity (mV/A)
100
Sensitivity Error vs. Temperature
68
67
66
66
65
65
64
64
0.0
-1.0
-2.0
-3.0
-4.0
-50
0
50
100
150
-50
0
Temperature (°C)
50
100
150
Temperature (°C)
Total Error at IPR(max) vs. Temperature
Nonlinearity vs. Temperature
2.0
3.0
1.5
2.0
1.0
1.0
Total Error (%)
Nonlinearity (%)
50
Temperature (°C)
0.5
0.0
-0.5
-1.0
0.0
-1.0
-2.0
-3.0
-4.0
-1.5
-5.0
-2.0
-50
0
50
100
150
-50
+3 Sigma
0
50
100
150
Temperature (°C)
Temperature (°C)
Average
-3 Sigma
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
9
High-Accuracy, Hall-Effect-Based Current Sensor IC with
Common-Mode Field Rejection in High-Isolation SOIC16 Package
ACS725KMA
CHARACTERISTIC PERFORMANCE
xKMATR-30AB
Offset Voltage vs. Temperature
1665
15
1660
10
Offset Voltage (mV)
VIOUT(Q) (mV)
Zero Current Output Voltage vs. Temperature
1655
1650
1645
1640
1635
5
0
-5
-10
-15
-50
0
50
100
150
-50
0
50
Temperature (°C)
150
Sensitivity Error vs. Temperature
45
2.0
45
1.0
Sensitivity Error (%)
Sensitivity (mV/A)
Sensitivity vs. Temperature
44
44
43
43
0.0
-1.0
-2.0
-3.0
-4.0
42
-5.0
-50
0
50
100
150
-50
0
Temperature (°C)
50
100
150
Temperature (°C)
Total Error at IPR(max) vs. Temperature
Nonlinearity vs. Temperature
2.0
2.0
1.5
1.0
1.0
Total Error (%)
Nonlinearity (%)
100
Temperature (°C)
0.5
0.0
-0.5
-1.0
0.0
-1.0
-2.0
-3.0
-1.5
-4.0
-2.0
-50
0
50
100
-50
150
+3 Sigma
0
50
100
150
Temperature (°C)
Temperature (°C)
Average
-3 Sigma
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
10
High-Accuracy, Hall-Effect-Based Current Sensor IC with
Common-Mode Field Rejection in High-Isolation SOIC16 Package
ACS725KMA
CHARACTERISTIC PERFORMANCE
xKMATR-30AU
Zero Current Output Voltage vs. Temperature
Offset Voltage vs. Temperature
20
345
15
Offset Voltage (mV)
350
VIOUT(Q) (mV)
340
335
330
325
320
315
310
10
5
0
-5
-10
-15
-20
305
-25
-50
0
50
100
150
-50
0
Temperature (°C)
Sensitivity vs. Temperature
150
2.0
89
1.0
Sensitivity Error (%)
89
Sensitivity (mV/A)
100
Sensitivity Error vs. Temperature
90
88
88
87
87
86
86
85
0.0
-1.0
-2.0
-3.0
-4.0
85
84
-5.0
-50
0
50
100
150
-50
0
Temperature (°C)
50
100
150
Temperature (°C)
Total Error at IPR(max) vs. Temperature
Nonlinearity vs. Temperature
2.0
2.0
1.5
1.0
1.0
Total Error (%)
Nonlinearity (%)
50
Temperature (°C)
0.5
0.0
-0.5
-1.0
0.0
-1.0
-2.0
-3.0
-4.0
-1.5
-5.0
-2.0
-50
0
50
100
150
-50
+3 Sigma
0
50
100
150
Temperature (°C)
Temperature (°C)
Average
-3 Sigma
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
11
High-Accuracy, Hall-Effect-Based Current Sensor IC with
Common-Mode Field Rejection in High-Isolation SOIC16 Package
ACS725KMA
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.
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 Figure 1 and Figure 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 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 due to
–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
High-Accuracy, Hall-Effect-Based Current Sensor IC with
Common-Mode Field Rejection in High-Isolation SOIC16 Package
ACS725KMA
APPLICATION INFORMATION
Estimating Total Error versus Sensed Current
The Performance Characteristics tables give distribution
(±3 sigma) values for Total Error at IPR(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
±3 sigma value for Total Error (ETOT) as a function of the sensed
current (IP) is estimated as:
2
ETOT(IP) = ESENS +
(
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 +
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 versus sensed current
(IP) is shown here for the ACS725KMATR-20AB. As expected,
as one goes towards zero current, the error in percent goes
towards infinity due to division by zero (refer to Figure 3).
20
Total Error (% of current measured)
15
10
5
–40°C +3σ
–40°C –3σ
0
25°C +3σ
25°C –3σ
–5
85°C +3σ
85°C –3σ
–10
–15
–20
0
5
10
15
20
25
Current (A)
Figure 3: Predicted Total Error as a Function of Sensed
Current for the ACS725KMATR-20AB
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
13
ACS725KMA
High-Accuracy, Hall-Effect-Based Current Sensor IC with
Common-Mode Field Rejection 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
VCC
VCC(typ)
VCC(min)
t1
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).
tPO
t2= time at which output voltage settles
within ±10% of its steady state value
under an applied magnetic field
0
t
Figure 4: Power-On Time
(%)
90
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).
t2
t1= time at which power supply reaches
minimum specified operating voltage
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 fullscale 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.
VIOUT
90% VIOUT
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 with
Common-Mode Field Rejection in High-Isolation SOIC16 Package
ACS725KMA
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 with
Common-Mode Field Rejection in High-Isolation SOIC16 Package
ACS725KMA
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
ACS725KMA
High-Accuracy, Hall-Effect-Based Current Sensor IC with
Common-Mode Field Rejection in High-Isolation SOIC16 Package
Revision History
Revision
Date
–
December 11, 2015
1
March 18, 2016
Description
Initial release
Added ACS725KMATR-30AB-T variant, UL/TUV certification; removed solder balls reference in Description
Copyright ©2016, 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