ACS730
1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 Package
FEATURES AND BENEFITS
DESCRIPTION
• Industry-leading noise performance with greatly
improved bandwidth through proprietary amplifier and
filter design techniques
• High bandwidth 1 MHz analog output
• Patented integrated digital temperature compensation
circuitry allows high accuracy over temperature in an
open loop sensor
• 1.2 mΩ primary conductor resistance for low power loss
and high inrush current withstanding capability
• Small footprint, low-profile SOIC8 package suitable for
space-constrained applications
• Integrated shield virtually eliminates capacitive coupling
from current conductor to die due to high dV/dt voltage
transients
• 5 V, single supply operation
• Output voltage proportional to AC or DC current
• Factory-trimmed sensitivity and quiescent output voltage
for improved accuracy
• High PSRR for noisy environments
The Allegro™ ACS730 current sensor family provides
economical and precise solutions for AC or DC current sensing
in industrial, commercial, and communications systems. The
device package allows for easy implementation by the customer.
Typical applications include motor control, load detection and
management, switched-mode power supplies, and overcurrent
fault protection.
The terminals of the conductive path are electrically isolated
from the sensor leads (pins 5 through 8). This allows the
ACS730 current sensor to be used in high-side current sense
applications without the use of high-side differential amplifiers
or other costly isolation techniques.
Package: 8-Pin SOIC (suffix LC)
The ACS730 is provided in a small, low-profile surface-mount
SOIC8 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.
Not to scale
1
2
IP
3
4
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 Hall IC, which is programmed
for accuracy after packaging. The output of the device has a
positive slope when an increasing current flows through the
primary copper conduction path (from pins 1 and 2, to pins 3
and 4), which is the path used for current sensing. The internal
resistance of this conductive path is typically 1.2 mΩ, providing
low power loss.
IP+
ACS730
VCC
IP+
VIOUT
IP–
VZCR
IP–
GND
8
7
6
5
Typical Application
ACS730-DS
CVZCR
1 nF
CBYPASS
0.1 µF
The ACS730 outputs an
analog signal, VIOUT, that
varies linearly with the
bidirectional AC or DC
primary sensed current,
IP, within the range specified.
1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 Package
ACS730
SELECTION GUIDE
Part Number
Optimized
Range, IP
(A)
Sensitivity1,
Sens(Typ)
(mV/A)
ACS730KLCTR-20AB-T
±20
100
ACS730KLCTR-40AB-T
±40
50
ACS730KLCTR-50AB-T
±50
40
1
2
TA
(°C)
Packing2
–40 to 125
Tape and reel, 3000 pieces per reel
Measured at VCC = 5 V
Contact Allegro for additional packing options.
SPECIFICATIONS
Absolute Maximum Ratings
Characteristic
Symbol
Notes
Rating
Units
Supply Voltage
VCC
6
V
Reverse Supply Voltage
VRCC
–0.1
V
Output Voltage
VIOUT
6
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 170
°C
Isolation Characteristics1
Characteristic
Dielectric Strength Test Voltage
Working Voltage for Basic Isolation
Clearance
Creepage
Symbol
Notes
Value
Units
VISO
Agency type-tested for 60 seconds per UL 60950-1
(edition 2); production-tested at 1500 VRMS for 1 second,
in accordance with UL 60950-1 (edition 2)
2400
VRMS
210 (2)
VPK or VDC
150
VRMS
VWVBI
Maximum approved working voltage for basic (single)
isolation according to UL 60950-1 (edition 2)
Dcl
Minimum distance through air from IP leads to signal leads
1.6
mm
Dcr
Minimum distance along package body from IP leads to
signal leads
1.6
mm
Pending UL certification.
Higher working voltages, up to 420 Vpk/Vdc and 297 Vrms are possible if the tie-bars on the side of the package are conformal-coated, effectively increasing the creepage
and clearance of the package to around 3.9 mm.
1
2
Thermal Characteristics
Characteristic
Symbol
Test Conditions3
Value
Units
Package Thermal Resistance
(Junction to Ambient)
RθJA
Mounted on the Allegro 85-xxxx evaluation board with
1500 mm2 of 2 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.4
23
°C/W
Package Thermal Resistance
(Junction to Lead)
RθJL
Mounted on the Allegro ASEK722 evaluation board.
5
°C/W
3 Additional
thermal information available on the Allegro website.
Further details on the board are available from the Frequently Asked Questions document on our website. Further information about board design and thermal performance
also can be found in the Applications Information section of this datasheet.
4
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 Package
ACS730
Functional Block Diagram
VCC
To All Subcircuits
POR
Temp
Sensor
Hall
Voltage
Regulator
Bandgap
Reference
Programming
Control
EEPROM and Control Logic
IP+
IP+
Fine
Sensitivity
Control
Coarse
Sensitivity
Control
Offset Control
and VZCR
Generation
VZCR
VIOUT
IP–
IP–
GND
Pinout Diagram and Terminal List Table
Terminal List Table
IP+
1
8
VCC
IP+
2
7
VIOUT
IP–
3
6
VZCR
IP–
4
5
GND
Package LC, 8-Pin SOICN
Pinout Diagram
Number
Name
1, 2
IP+
3, 4
IP–
5
GND
Description
Terminals for current being sensed; fused internally
Terminals for current being sensed; fused internally
Signal ground terminal
6
VZCR
Zero count reference
7
VIOUT
Analog output signal
8
VCC
Device power supply terminal
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 Package
ACS730
COMMON ELECTRICAL CHARACTERISTICS1: Valid over full range of TA , VCC = 5 V, unless otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Unit
Supply Voltage
VCC
4.5
5
5.5
V
Supply Current
ICC
VCC = 5 V, output open
–
17
25
mA
Power-On Time
tPO
TA = 25°C
–
150
–
μs
Output Capacitance Load
CL
VIOUT to GND
–
–
0.47
nF
CVZCR
VZCR to GND
–
–
1
nF
RL
VIOUT to GND, VIOUT to VCC
10
–
–
kΩ
RVZCR
VIOUT to GND, VZCR to VCC
10
–
–
kΩ
Reference Capacitance Load
Output Resistive Load
Reference Resistive Load
Voltage2
Output High Saturation
VOH
VIOUT, TA = 25°C
VCC – 0.4
VCC – 0.3
–
V
Output Low Saturation Voltage2
VOL
VIOUT, TA = 25°C
–
0.1
0.2
V
RIP
TA = 25°C
–
1.2
–
mΩ
MCF
TA = 25°C
–
10
–
G/A
tr
TA = 25°C, CL = 0.47 nF, 1 V step on output
–
0.6
–
μs
tRESPONSE
TA = 25°C, CL = 0.47 nF, 1 V step on output
–
0.7
–
μs
Small signal –3 dB; CL = 0.47 nF
–
1
–
MHz
Primary Conductor Resistance
Magnetic Coupling Factor
Rise Time
Response Time
Internal Bandwidth
BW
–
40
–
µA(rms)/
√Hz
Noise Density
IND(rms)
Input referenced noise density;
TA = 25°C, CL = 0.47 nF
Power Supply Rejection Ratio
PSRR
0 to 200 Hz, 100 mV pk-pk ripple on VCC,
IP = 0 A, VIOUT and VZCR
–
35
–
dB
–
15
–
dB
Sensitivity Power Supply Rejection Ratio
SPSRR
DC, VCC(min) < VCC < VCC(max), IP =
IPR(max)
Offset Power Supply Rejection Ratio
OPSRR
DC, VCC(min) < VCC < VCC(max)
–
30
–
dB
Output Source Current
IOUT(src)
VIOUT shorted to GND
–
5.5
–
mA
Output Sink Current
IOUT(snk)
VIOUT shorted to VCC
–
3
–
mA
TA = 25°C
–
2.5
–
V
TA = 25°C
–10
±3
10
mV
TA = 25°C to 125°C
–20
±10
20
mV
TA = –40°C to 25°C
–
±10
–
mV
Zero Current Reference Voltage
Zero Current Reference Offset Voltage
VZCR
VZCR(ofs)
Reference Source Current
IVZCR(src)
VZCR shorted to GND
–
2
–
mA
Reference Sink Current
IVZCR(snk)
VZCR shored to VCC
–
14
–
mA
1 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.
2 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.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 Package
ACS730
xKLCTR-20AB PERFORMANCE CHARACTERISTICS: Valid over full range of TA, VCC = 5 V, unless otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.1
Max.
Unit
–20
–
20
A
NOMINAL PERFORMANCE
Current Sensing Range
Sensitivity
Zero Current Output Voltage
IPR
Sens
VIOUT(Q)
–
100
–
mV/A
IP = 0 A, TA = 25°C
–
2.5
–
V
IP = 20 A; TA = 25°C to 125°C
–4
±3
4
%
ACCURACY PERFORMANCE
Total Output Error2
Sensitivity Error
Offset Voltage
Nonlinearity
ETOT
Esens
VOE
ELIN
IP = 20 A; TA = –40°C to 25°C
–
±4
–
%
IP = 20 A; TA = 25°C to 125°C
–2.5
±1.5
2.5
%
IP = 20 A; TA = –40°C to 25°C
–
±4
–
%
IP = 0 A; TA = 25°C to 125°C
–75
±50
75
mV
IP = 0 A; TA = –40°C to 25°C
–
±50
–
mV
IP within IPOA, TA = 25°C to 125°C
–2
±0.75
2
%
IP within IPOA, TA = –40°C to 25°C
–
±0.75
–
%
±1.5
–
%
LIFETIME DRIFT CHARACTERISTICS
Total Output Error Lifetime Drift
Etot_drift
IP = 20 A
–
Sensitivity Error Lifetime Drift
Esens_drift
IP = 20 A
–
±1
–
%
Voff_drift
IP = 0 A
–
±20
–
mV
Offset Voltage Lifetime Drift
1
Typical values with ± are 3 sigma values, except for Lifetime Drift which are mean values.
of IP , output filtered.
2 Percentage
xKLCTR-40AB PERFORMANCE CHARACTERISTICS: Valid over full range of TA, VCC = 5 V, unless otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.1
Max.
Unit
–40
–
40
A
NOMINAL PERFORMANCE
Current Sensing Range
Sensitivity
Zero Current Output Voltage
IPR
Sens
VIOUT(Q)
–
50
–
mV/A
IP = 0 A, TA = 25°C
–
2.5
–
V
IP = 20 A; TA = 25°C to 125°C
–4
±3
4
%
IP = 20 A; TA = –40°C to 25°C
–
±4.5
–
%
IP = 40 A; TA = 25°C to 125°C
–5
±3
5
%
IP = 40 A; TA = –40°C to 25°C
–
±5
–
%
IP = 20 A; TA = 25°C to 125°C
–2.5
±2
2.5
%
IP = 20 A; TA = –40°C to 25°C
–
±3.5
–
%
IP = 40 A; TA = 25°C to 125°C
–3.5
±2.5
3.5
%
IP = 40 A; TA = –40°C to 25°C
–
±5
–
%
IP = 0 A; TA = 25°C to 125°C
–40
±20
40
mV
IP = 0 A; TA = –40°C to 25°C
–
±30
–
mV
IP within IPOA, TA = 25°C to 125°C
–2
±0.75
2
%
IP within IPOA, TA = –40°C to 25°C
–
±0.75
–
%
ACCURACY PERFORMANCE
Total Output Error2
Sensitivity Error
ETOT
Esens
Offset Voltage
VOE
Nonlinearity
ELIN
LIFETIME DRIFT CHARACTERISTICS
Total Output Error Lifetime Drift
Etot_drift
IP = 40 A
–
±1.5
–
%
Sensitivity Error Lifetime Drift
Esens_drift
IP = 20 A
–
±1
–
%
Voff_drift
IP = 0 A
–
±20
–
mV
Offset Voltage Lifetime Drift
Typical values with ± are 3 sigma values, except for Lifetime Drift which are mean values.
2 Percentage of I , output filtered.
P 1
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 Package
ACS730
xKLCTR-50AB PERFORMANCE CHARACTERISTICS: Valid over full range of TA, VCC = 5 V, unless otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.1
Max.
Unit
NOMINAL PERFORMANCE
Current Sensing Range
Sensitivity
Zero Current Output Voltage
IPR
–50
–
50
A
Sens
–
40
–
mV/A
IP = 0 A, TA = 25°C
–
2.5
–
V
IP = 25 A; TA = 25°C to 125°C
–4
±3
4
%
IP = 25 A; TA = –40°C to 25°C
–
±5
–
%
IP = 50 A; TA = 25°C to 125°C
–5
±3
5
%
IP = 50 A; TA = –40°C to 25°C
–
±5
–
%
IP = 25 A; TA = 25°C to 125°C
–2.5
±2
2.5
%
IP = 25 A; TA = –40°C to 25°C
–
±4
–
%
IP = 50 A; TA = 25°C to 125°C
–3.5
±3
3.5
%
VIOUT(Q)
ACCURACY PERFORMANCE
Total Output Error2
Sensitivity Error
Offset Voltage
Nonlinearity
ETOT
Esens
VOE
ELIN
IP = 50 A; TA = –40°C to 25°C
–
±5
–
%
IP = 0 A; TA = 25°C to 125°C
–40
±20
40
mV
IP = 0 A; TA = –40°C to 25°C
–
±30
–
mV
IP within IPOA, TA = 25°C to 125°C
–2
±0.75
2
%
IP within IPOA, TA = –40°C to 25°C
–
±0.75
–
%
LIFETIME DRIFT CHARACTERISTICS
Total Output Error Lifetime Drift
Etot_drift
IP = 50 A
–
±1.5
–
%
Sensitivity Error Lifetime Drift
Esens_drift
IP = 25 A
–
±1
–
%
Voff_drift
IP = 0 A
–
±20
–
mV
Offset Voltage Lifetime Drift
Typical values with ± are 3 sigma values, except for Lifetime Drift which are mean values.
2 Percentage of I , output filtered.
P 1
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
6
ACS730
1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 Package
CHARACTERISTIC PERFORMANCE
Response Time (tRESPONSE)
10 A input signal (IP) with rise time < 1 µs
Sensitivity = 100 mV/A, CBYPASS = 0.1 µF, CL = 470 pF, VZCR = 1 nF
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
7
ACS730
1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 Package
Propagation Delay (tPD)
10 A input signal (IP) with rise time < 1 µs
Sensitivity = 100 mV/A, CBYPASS = 0.1 µF, CL = 470 pF, VZCR = 1 nF
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
8
ACS730
1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 Package
Rise Time (tRISE)
10 A input signal (IP) with rise time < 1 µs
Sensitivity = 100 mV/A, CBYPASS = 0.1 µF, CL = 470 pF, VZCR = 1 nF
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
9
1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 Package
ACS730
CHARACTERISTIC PERFORMANCE
xKLCTR-20AB Key Parameters
Zero Current Output Voltage Error vs. Temperature
Zero Current Reference Voltage Error vs. Temperature
15
60
Offset Voltage (mV)
Offset Voltage (mV)
80
40
20
0
-20
-40
-60
10
5
0
-5
-10
-50
0
50
100
150
-50
0
Temperature (°C)
1.0
1.0
0.0
0.0
Sensitivity Error (%)
Sensitivity Error (%)
100
150
Sensitivity Error Full Scale vs. Temperature
Sensitivity Error Half Scale vs. Temperature
-1.0
-2.0
-3.0
-4.0
-1.0
-2.0
-3.0
-4.0
-5.0
-5.0
-50
0
50
100
-50
150
0
50
100
150
Temperature (°C)
Temperature (°C)
Nonlinearity vs. Temperature
Total Error at IPR(max) 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
-6.0
-50
0
50
100
150
-50
Temperature (°C)
0
50
100
150
Temperature (°C)
+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
1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 Package
ACS730
xKLCTR-40AB Key Parameters
Zero Current Output Voltage Error vs. Temperature
Zero Current Reference Voltage Error vs. Temperature
20
Offset Voltage (mV)
Offset Voltage (mV)
30
10
0
-10
-20
-30
-50
0
50
100
12
10
8
6
4
2
0
-2
-4
-6
-8
-10
150
-50
0
Temperature (°C)
1.5
2.0
1.0
1.0
0.5
Sensitivity Error (%)
Sensitivity Error (%)
100
150
Sensitivity Error Full Scale vs. Temperature
Sensitivity Error Half Scale vs. Temperature
0.0
-0.5
-1.0
-1.5
-2.0
-2.5
0.0
-1.0
-2.0
-3.0
-4.0
-5.0
-3.0
-6.0
-3.5
-50
0
50
100
-50
150
0
50
100
150
Temperature (°C)
Temperature (°C)
Nonlinearity vs. Temperature
Total Error at IPR(max) vs. Temperature
3.0
3.0
2.5
2.0
2.0
1.0
Total Error (%)
Nonlinearity (%)
50
Temperature (°C)
1.5
1.0
0.5
0.0
0.0
-1.0
-2.0
-3.0
-4.0
-0.5
-5.0
-1.0
-6.0
-50
0
50
100
150
-50
Temperature (°C)
+3 Sigma
0
50
100
150
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
1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 Package
ACS730
xKLCTR-50AB Key Parameters
Zero Current Output Voltage Error vs. Temperature
Zero Current Reference Voltage Error vs. Temperature
12
10
30
Offset Voltage (mV)
Offset Voltage (mV)
40
20
10
0
-10
-20
8
6
4
2
0
-2
-4
-6
-30
-8
-50
0
50
100
150
-50
0
Temperature (°C)
2.0
2.0
1.5
1.0
1.0
Sensitivity Error (%)
Sensitivity Error (%)
100
150
Sensitivity Error Full Scale vs. Temperature
Sensitivity Error Half Scale vs. Temperature
0.5
0.0
-0.5
-1.0
-1.5
0.0
-1.0
-2.0
-3.0
-4.0
-5.0
-2.0
-6.0
-2.5
-50
0
50
100
-50
150
0
50
100
150
Temperature (°C)
Temperature (°C)
Nonlinearity vs. Temperature
Total Error at IPR(max) vs. Temperature
5.0
2.0
1.0
4.0
0.0
Total Error (%)
Nonlinearity (%)
50
Temperature (°C)
3.0
2.0
1.0
0.0
-1.0
-2.0
-3.0
-4.0
-5.0
-1.0
-6.0
-50
0
50
100
150
-50
Temperature (°C)
+3 Sigma
0
50
100
150
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
12
1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 Package
ACS730
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 circuit sensitivity (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.
Increasing
VIOUT (V)
ELIN =
{
1–
VIOUT (IR(max)) – VIOUT(Q)
2 • VIOUT (IR(max)/2) – VIOUT(Q)
}
Accuracy at
25°C Only
IPR(min)
• 100(%)
–IP (A)
Full Scale IP
Accuracy at
25°C Only
Decreasing
VIOUT (V)
Accuracy Across
Temperature
Figure 1: Output Voltage versus Sensed Current
+ETOT
VIOUT_IDEAL(IP) – VIOUT(IP)
• 100 (%)
SensIDEAL × IP
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 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 .
IPR(max)
0A
Offset Voltage (VOE). The deviation of the device output from
its ideal quiescent value of 2.5 V due to nonmagnetic causes. To
convert this voltage to amperes, divide by the device sensitivity,
Sens.
ETOT (IP) =
+IP (A)
VIOUT(Q)
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 2.5 V for a bidirectional device.
Variation in VIOUT(Q) can be attributed to the resolution of the
Allegro linear IC quiescent voltage trim and thermal drift.
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:
Accuracy at
25°C Only
Ideal VIOUT
Accuracy Across
Temperature
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:
Accuracy Across
Temperature
Across Temperature
25°C Only
–IP
+IP
–ETOT
Figure 2: Total Output Error versus Sensed Current
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1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 Package
ACS730
Power Supply Rejection Ratio (PSRR). The ratio of the change
on VIOUT or VZCR to a change in VCC in dB.
PSRR = 20 log10
(|
ΔVCC
ΔVIOUT
|)
OPSRR = 20 log10
Sensitivity Power Supply Rejection Ratio (PSRR). The ratio of
the percent change in sensitivity from the sensitivity at 5 V to the
percent change in VCC in dB.
SPSRR (VCC) = 20 log10
(|
Sens5V × (VCC – 5 V)
[SensVCC × Sens5V] × 5 V
Offset Power Supply Rejection Ratio (OPSRR). The ratio of
the change in offset to a change in VCC in dB.
(|
ΔVCC
ΔVOE
|)
An OPSRR value of 30 dB means that a 500 mV change in VCC
(going from 5 to 5.5 V, for example) results in around 15 mV of
change in the offset.
|)
A SPSRR value of 15 dB means that a ten percent change in VCC
(going from 5 to 5.5 V, for example) results in around a 1.75 percent change in sensitivity.
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115 Northeast Cutoff
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14
1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 Package
ACS730
APPLICATION INFORMATION
Impact of External Magnetic Fields
Estimating Total Error vs. Sensed Current
The ACS730 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:
The Performance Characteristics tables give distribution values
(±3 sigma) for Total Error at IP(max) and IP(half); 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:
Error (B) =
B
MCF
2
ETOT (IP) = ESENS +
where B is the strength of the external field perpendicular to the
surface of the package in gauss (G), and MCF is the magnetic
coupling factor in gauss/amperes (G/A). Then, multiplying by
the sensitivity of the part (Sens) gives the error in mV seen at the
output.
For example, an external field of 1 gauss will result in around
0.1 A of error. If the ACS730KLCTR-20AB, which has a nominal
sensitivity of 100 mV/A, is being used, that equates to 10 mV of
error on the output of the sensor.
External Field
(Gauss)
Error
(A)
0.5
1
2
Error (mV)
20B
40B
50B
0.05
5
2.5
2
0.1
10
5
4
0.2
20
10
8
(
100 × VOE
Sens × IP
2
)
Here, ESENS and VOE are the ±3 sigma values for those error
terms. If there is an 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 below for the ACS730KLCTR-20AB. As expected, as the
sensed current (IP) approaches zero, the error in percent goes
towards infinity due to division by zero (refer to Figure 3).
Total Error (% of current measured)
20.00
15.00
10.00
-40ºC + 3σ
5.00
-40ºC – 3σ
0.00
25ºC + 3σ
-5.00
125ºC + 3σ
25ºC – 3σ
125ºC – 3σ
-10.00
-15.00
-20.00
0
2
4
6
8
10
12
14
16
18
20
Current (A)
Figure 3: Predicted Total Error as a Function of the Sensed Current for the ACS730KLCTR-20AB
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ACS730
1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 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.
V
VCC
VCC(typ.)
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
0
Rise Time (tr). The time interval between a) when the sensor
reaches 10% of its full-scale value, and b) when it reaches 90% of
its full scale value.
Propagation Delay (tpd ). The time interval between a) when the
sensed input current reaches 20% of its full-scale value, and b)
when the sensor output reaches 20% of its full-scale value.
(%)
90
Figure 3: Power-On Time (tPO)
t
Primary Current
VIOUT
Rise Time, tr
20
10
0
Propagation Delay, tpd
t
Figure 4: Rise Time (tr) and Propagation Delay (tpd)
Response Time (tRESPONSE). The time interval between a) when
the sensed input current reaches 90% of its final value, and b)
when the sensor output reaches 90% of its full-scale value.
(%)
90
Primary Current
VIOUT
Response Time, tRESPONSE
0
Figure 5: Response Time (tRESPONSE)
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t
16
1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 Package
ACS730
PACKAGE OUTLING DRAWING
For Reference Only – Not for Tooling Use
(Reference MS-012AA)
Dimensions in millimeters – NOT TO SCALE
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
8°
0°
4.90 ±0.10
1.27
0.65
8
8
0.25
0.17
3.90 ±0.10
5.60
6.00 ±0.20
A
1.04 REF
1
1.75
2
1
1.27
0.40
C
2
PCB Layout Reference View
0.25 BSC
SEATING PLANE
Branded Face
GAUGE PLANE
C
8X
0.10
1.75 MAX
C
NNNNNNN
SEATING
PLANE
PPT-AAA
LLLLL
0.51
0.31
0.25
0.10
1.27 BSC
1
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.
B
Standard Branding Reference View
N = Device part number
P = Package Designator
T = Device temperature range
A = Amperage
L = Lot number
Belly Brand = Country of Origin
Figure 6: Package LC, 8-Pin SOICN
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17
1 MHz Bandwidth, Galvanically Isolated Current Sensor IC
in Small Footprint SOIC8 Package
ACS730
Revision History
Revision
Revision Date
–
February 29, 2016
Description of Revision
Initial release
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
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115 Northeast Cutoff
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18