ACS725 Datasheet

ACS725
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 Package
FEATURES AND BENEFITS
DESCRIPTION
• Differential Hall sensing rejects common-mode fields
• 1.2 mΩ primary conductor resistance for low power loss
and high inrush current withstand capability
• Integrated shield virtually eliminates capacitive coupling
from current conductor to die, greatly suppressing output
noise due to high dv/dt transients
• Industry-leading noise performance with greatly
improved bandwidth through proprietary amplifier and
filter design techniques
• High-bandwidth 120 kHz analog output for faster
response times in control applications
• Filter pin allows user to filter the output for improved
resolution at lower bandwidth
• Patented integrated digital temperature compensation
circuitry allows for near closed loop accuracy over
temperature in an open-loop sensor
• Small footprint, low-profile SOIC8 package suitable for
space-constrained applications
• Filter pin simplifies bandwidth limiting for better
resolution at lower frequencies
The Allegro™ ACS725 current sensor IC is an economical and
precise solution for AC or DC current sensing in industrial,
automotive, commercial, and communications 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 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 1.2 mΩ typical,
providing low power loss.
Continued on the next page…
Package: 8-Pin SOIC (suffix LC)
pe d
Ty ste
te
TÜV America
Certificate Number:
U8V 14 11 54214 032
CB 14 11 54214 031
CB Certificate Number:
US-22334-A2-UL
The terminals of the conductive path are electrically isolated
from the sensor leads (pins 5 through 8). This allows the
ACS725 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.
Continued on the next page…
Not to scale
1
VCC
IP+
+IP
8
ACS725
2
IP+
VIOUT
7
IP
3
IP–
FILTER
CBYPASS
0.1 µF
6
–IP
4
IP–
GND
5
CF
1 nF
Typical Application
ACS725-DS, Rev. 2
CLOAD
The ACS725 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.
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 Package
ACS725
Features and Benefits (continued)
Description (continued)
• 3.3 V, single supply operation
• Output voltage proportional to AC or DC current
• 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
The ACS725 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.
Selection Guide
Part Number
IPR
(A)
Sens(Typ)
at VCC = 3.3 V
(mV/A)
ACS725LLCTR-10AU-T
10
264
ACS725LLCTR-20AB-T
±20
66
ACS725LLCTR-20AU-T
20
132
ACS725LLCTR-30AB-T
±30
44
ACS725LLCTR-30AU-T
30
88
ACS725LLCTR-40AB-T
±40
33
TA
(°C)
Packing*
-40 to 150
Tape and Reel, 3000 pieces per reel
*Contact Allegro 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
ACS725
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 Package
SPECIFICATIONS
Absolute Maximum Ratings
Characteristic
Supply Voltage
Symbol
Notes
VCC
Rating
Units
6
V
Reverse Supply Voltage
VRCC
–0.1
V
Output Voltage
VIOUT
VCC + 0.5
V
Reverse Output Voltage
VRIOUT
Operating Ambient Temperature
TA
Range L
–0.1
V
–40 to 150
°C
Junction Temperature
TJ(max)
165
°C
Storage Temperature
Tstg
–65 to 165
°C
Isolation Characteristics
Characteristic
Dielectric Strength Test Voltage
Working Voltage for Basic Isolation
Clearance
Creepage
Symbol
Notes
Rating
Unit
VISO
Agency type-tested for 60 seconds per UL standard
60950-1 (edition 2). Production tested at VISO for 1 second,
in accordance with UL 60950-1 (edition 2).
2400
VRMS
Maximum approved working voltage for basic (single)
isolation according UL 60950-1 (edition 2)
420
Vpk or VDC
297
Vrms
Dcl
Minimum distance through air from IP leads to signal leads
3.9
mm
Dcr
Minimum distance along package body from IP leadds to
signal leads
3.9
mm
VWVBI
Thermal Characteristics
Characteristic
Symbol
Test Conditions*
Value
Units
Package Thermal Resistance
(Junction to Ambient)
RθJA
Mounted on the Allegro 85-0140 evaluation board with 800
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 ASEK725 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
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 Package
ACS725
VCC
VCC
Master Current
Supply
To All Subcircuits
Programming
Control
POR
Hall
Current
Drive
CBYPASS
0.1 µF
EEPROM and
Control Logic
Temperature
Sensor
Offset
Control
IP+
Sensitivity
Control
Dynamic Offset
Cancellation
IP+
IP–
+
–
RF(int)
+
–
VIOUT
IP–
GND
CF
FILTER
Functional Block Diagram
Pinout Diagram and Terminal List Table
Terminal List Table
IP+
1
8
VCC
IP+
2
7
VIOUT
IP–
3
6
FILTER
IP–
4
5
GND
Package LC, 8-Pin SOICN
Pinout Diagram
Number
Name
1, 2
IP+
Description
Terminals for current being sensed; fused internally
3, 4
IP–
5
GND
Terminals for current being sensed; fused internally
6
FILTER
Terminal for external capacitor that sets bandwidth
7
VIOUT
Analog output signal
8
VCC
Signal ground terminal
Device power supply terminal
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
ACS725
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 Package
COMMON ELECTRICAL CHARACTERISTICS1: valid through the full range of TA , VCC = 3.3 V, CF = 0, unless otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Unit
3
3.3
3.6
V
–
10
14
mA
Supply Voltage
VCC
Supply Current
ICC
VCC = 3.3 V, output open
Output Capacitance Load
CL
VIOUT to GND
–
–
10
nF
Output Resistive Load
RL
VIOUT to GND
4.7
–
–
kΩ
RIP
TA = 25°C
–
1.2
–
mΩ
–
1.8
–
kΩ
Primary Conductor Resistance
Internal Filter Resistance2
Primary Hall Coupling Factor
Secondary Hall Coupling Factor
Hall plate Sensitivity Matching
RF(int)
G1
TA = 25ºC
–
11
–
G/A
G2
TA = 25ºC
–
2.8
–
G/A
Sensmatch
TA = 25ºC
–
±1
–
%
Rise Time
tr
IP = IP(max), TA = 25°C, CL = 1 nF
–
3
–
μs
Propagation Delay
tpd
IP = IP(max), TA = 25°C, CL = 1 nF
–
2
–
μs
Response Time
tRESPONSE
IP = IP(max), TA = 25°C, CL = 1 nF
–
4
–
μs
Bandwidth
BW
Small signal –3 dB; CL = 1 nF
–
120
–
kHz
Noise Density
IND
Input referenced noise density;
TA = 25°C, CL = 1 nF
–
200
–
µA(rms)/
√Hz
Noise
IN
Input referenced noise: CF = 4.7 nF,
CL = 1 nF, BW = 18 kHz, TA = 25°C
–
27
–
mA(rms)
–1.5
–
+1.5
%
Nonlinearity
ELIN
Through full range of IP
Sensitivity Ratiometry Coefficient
SENS_RAT_
COEF
VCC = 3.0 to 3.6 V, TA = 25ºC
–
1.3
–
–
Zero Current Output Ratiometry Coefficient
QVO_RAT_
COEF
VCC = 3.0 to 3.6 V, TA = 25ºC
–
1
–
–
VOH
RL = 4.7 kΩ
–
VCC – 0.3
–
V
VOL
RL = 4.7 kΩ
–
0.3
–
V
tPO
Output reaches 90% of steady-state
level, TA = 25°C, IP = IPR(max) applied
–
80
–
μs
Saturation Voltage3
Power-On Time
Shorted Output to Ground Current
Isc(gnd)
TA = 25ºC
–
3.3
–
mA
Shorted Output to VCC Current
Isc(vcc)
TA = 25ºC
–
45
–
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.
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.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 Package
ACS725
xLLCTR-10AU PERFORMANCE CHARACTERISTICS: TA Range L, valid at TA = – 40°C to 150°C, VCC = 3.3 V, unless
otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.1
Max.
Unit
Nominal Performance
Current Sensing Range
Sensitivity
Zero Current Output Voltage
IPR
0
–
10
A
IPR(min) < IP < IPR(max)
–
264
–
mV/A
Unidirectional; IP = 0 A
–
VCC ×
0.1
–
V
IP = IPR(max); TA = 25°C to 150ºC
–2.5
±0.9
2.5
IP = IPR(max); TA = –40°C to 25ºC
-6
±4
6
IP = IPR(max); TA = 25°C to 150ºC
–2
±0.9
2
IP = IPR(max); TA = –40°C to 25ºC
–5.5
±4
5.5
IP = 0 A; TA = 25°C to 150ºC
–15
±5
15
IP = 0 A; TA = –40°C to 25ºC
–30
±15
30
Esens_drift
–3
±1
3
%
Etot_drift
–3
±1
3
%
Sens
VIOUT(Q)
Accuracy Performance
Total Output Error2
ETOT
%
Total Output Error Components3 ETOT = ESENS + 100 x VOE/(Sens x IP)
Sensitivity Error
Esens
Offset Voltage
VOE
%
mV
Lifetime Drift Characteristics
Sensitivity Error Lifetime Drift
Total Output Error Lifetime
Drift
Typical values with ± are 3 sigma values
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 Percentage
xLLCTR-20AU PERFORMANCE CHARACTERISTICS: TA Range L, valid at TA = – 40°C to 150°C, VCC = 3.3 V, unless
otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.1
Max.
Unit
Nominal Performance
Current Sensing Range
Sensitivity
Zero Current Output Voltage
IPR
0
–
20
A
IPR(min) < IP < IPR(max)
–
132
–
mV/A
Unidirectional; IP = 0 A
–
VCC ×
0.1
–
V
IP = IPR(max); TA = 25°C to 150ºC
–2
±0.8
2
IP = IPR(max); TA = –40°C to 25ºC
–6
±4
6
IP = IPR(max); TA = 25°C to 150ºC
–1.5
±0.8
1.5
IP = IPR(max); TA = –40°C to 25ºC
–5.5
±4
5.5
IP = 0 A; TA = 25°C to 150ºC
–10
±4
10
IP = 0 A; TA = –40°C to 25ºC
–30
±5
30
Esens_drift
–3
±1
3
%
Etot_drift
–3
±1
3
%
Sens
VIOUT(Q)
Accuracy Performance
Total Output Error2
ETOT
%
Total Output Error Components3 ETOT = ESENS + 100 x VOE/(Sens x IP)
Sensitivity Error
Esens
Offset Voltage
VOE
%
mV
Lifetime Drift Characteristics
Sensitivity Error Lifetime Drift
Total Output Error Lifetime
Drift
Typical values with ± are 3 sigma values
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 Percentage
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
6
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 Package
ACS725
xLLCTR-20AB PERFORMANCE CHARACTERISTICS: TA Range L, valid at TA = – 40°C to 150°C, VCC = 3.3 V, unless
otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.1
Max.
Unit
–20
–
20
A
–
66
–
mV/A
Bidirectional; IP = 0 A
–
VCC ×
0.5
–
V
IP = IPR(max); TA = 25°C to 150ºC
–2
±0.8
2
IP = IPR(max); TA = –40°C to 25ºC
–6
±4
6
IP = IPR(max); TA = 25°C to 150ºC
–1.5
±0.8
1.5
IP = IPR(max); TA = –40°C to 25ºC
–5.5
±4
5.5
IP = 0 A; TA = 25°C to 150ºC
–10
±4
10
IP = 0 A; TA = –40°C to 25ºC
–30
±5
30
Esens_drift
–3
±1
3
%
Etot_drift
–3
±1
3
%
Nominal Performance
Current Sensing Range
Sensitivity
Zero Current Output Voltage
IPR
Sens
VIOUT(Q)
IPR(min) < IP < IPR(max)
Accuracy Performance
Total Output Error2
ETOT
%
Total Output Error Components3 ETOT = ESENS + 100 x VOE/(Sens x IP)
Sensitivity Error
Esens
Offset Voltage
VOE
%
mV
Lifetime Drift Characteristics
Sensitivity Error Lifetime Drift
Total Output Error Lifetime
Drift
Typical values with ± are 3 sigma values
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 Percentage
xLLCTR-30AB PERFORMANCE CHARACTERISTICS: TA Range L, valid at TA = – 40°C to 150°C, VCC = 3.3 V, unless
otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.1
Max.
Unit
–30
–
30
A
–
44
–
mV/A
Bidirectional; IP = 0 A
–
VCC ×
0.5
–
V
IP = IPR(max); TA = 25°C to 150ºC
–2
±0.7
2
IP = IPR(max); TA = –40°C to 25ºC
–6
±4
6
IP = IPR(max); TA = 25°C to 150ºC
–1.5
±0.7
1.5
IP = IPR(max); TA = –40°C to 25ºC
–5.5
±4
5.5
IP = 0 A; TA = 25°C to 150ºC
–10
±3
10
IP = 0 A; TA = –40°C to 25ºC
–30
±5
30
Esens_drift
–3
±1
3
%
Etot_drift
–3
±1
3
%
Nominal Performance
Current Sensing Range
Sensitivity
Zero Current Output Voltage
IPR
Sens
VIOUT(Q)
IPR(min) < IP < IPR(max)
Accuracy Performance
Total Output Error2
ETOT
%
Total Output Error Components3 ETOT = ESENS + 100 x VOE/(Sens x IP)
Sensitivity Error
Esens
Offset Voltage
VOE
%
mV
Lifetime Drift Characteristics
Sensitivity Error Lifetime Drift
Total Output Error Lifetime
Drift
Typical values with ± are 3 sigma values
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 Percentage
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
7
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 Package
ACS725
xLLCTR-30AU PERFORMANCE CHARACTERISTICS: TA Range L, valid at TA = – 40°C to 150°C, VCC = 3.3 V, unless
otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.1
Max.
Unit
0
–
30
A
–
88
–
mV/A
Unidirectional; IP = 0 A
–
VCC ×
0.1
–
V
IP = IPR(max); TA = 25°C to 150ºC
–2
±0.8
2
IP = IPR(max); TA = –40°C to 25ºC
–6
±4
6
IP = IPR(max); TA = 25°C to 150ºC
–1.5
±0.8
1.5
IP = IPR(max); TA = –40°C to 25ºC
–5.5
±4
5.5
IP = 0 A; TA = 25°C to 150ºC
–10
±4
10
IP = 0 A; TA = –40°C to 25ºC
–30
±5
30
Esens_drift
–3
±1
3
%
Etot_drift
–3
±1
3
%
Nominal Performance
Current Sensing Range
Sensitivity
Zero Current Output Voltage
IPR
Sens
VIOUT(Q)
IPR(min) < IP < IPR(max)
Accuracy Performance
Total Output Error2
ETOT
%
Total Output Error Components3 ETOT = ESENS + 100 x VOE/(Sens x IP)
Sensitivity Error
Esens
Offset Voltage
VOE
%
mV
Lifetime Drift Characteristics
Sensitivity Error Lifetime Drift
Total Output Error Lifetime
Drift
Typical values with ± are 3 sigma values
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 Percentage
xLLCTR-40AB PERFORMANCE CHARACTERISTICS: TA Range L, valid at TA = – 40°C to 150°C, VCC = 3.3 V, unless
otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.1
Max.
Unit
Nominal Performance
Current Sensing Range
Sensitivity
Zero Current Output Voltage
IPR
–40
–
40
A
Sens
IPR(min) < IP < IPR(max)
–
33
–
mV/A
VIOUT(Q)
Bidirectional; IP = 0 A
–
VCC ×
0.5
–
V
IP = IPR(max); TA = 25°C to 150ºC
–2
±1
2
IP = IPR(max); TA = –40°C to 25ºC
–6
±4
6
IP = IPR(max); TA = 25°C to 150ºC
–1.5
±1
1.5
IP = IPR(max); TA = –40°C to 25ºC
–5.5
±4
5.5
IP = 0 A; TA = 25°C to 150ºC
–10
±3
10
IP = 0 A; TA = –40°C to 25ºC
–30
±5
30
Esens_drift
–3
±1
3
%
Etot_drift
–3
±1
3
%
Accuracy Performance
Total Output Error2
ETOT
%
Total Output Error Components3 ETOT = ESENS + 100 x VOE/(Sens x IP)
Sensitivity Error
Esens
Offset Voltage
VOE
%
mV
Lifetime Drift Characteristics
Sensitivity Error Lifetime Drift
Total Output Error Lifetime
Drift
Typical values with ± are 3 sigma values
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.
1
2 Percentage
3 A single
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
8
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 Package
ACS725
CHARACTERISTIC PERFORMANCE
xLLCTR-10AU
Offset Voltage vs. Temperature
Zero Current Output Voltage vs. Temperature
20
345
15
Offset Voltage (mV)
350
VIOUT(Q) (mV)
340
335
330
325
320
10
5
0
-5
-10
-15
315
310
-20
-50
0
50
100
150
-50
0
Temperature (ºC)
50
100
150
Temperature (ºC)
Sensitivity Error vs. Temperature
Sensitivity vs. Temperature
1
268
266
Sensitivity Error (%)
Sensitivity (mV/A)
0
264
262
260
258
256
254
-1
-2
-3
-4
252
250
-5
-50
0
50
100
-50
150
0
50
100
150
Temperature (ºC)
Temperature (ºC)
Nonlinearity vs. Temperature
Total Error at IPR(max) vs. Temperature
1.00
2
0.80
1
0
0.40
Total Error (%)
Nonlinearity (%)
0.60
0.20
0.00
-0.20
-0.40
-1
-2
-3
-4
-0.60
-5
-0.80
-6
-1.00
-50
0
50
100
-50
150
Temperature (ºC)
+3 Sigma
0
50
100
150
Temperature (ºC)
Average
-3 Sigma
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
9
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 Package
ACS725
xLLCTR-20AU
Offset Voltage vs. Temperature
6.00
334
4.00
Offset Voltage (mV)
VIOUT(Q) (mV)
Zero Current Output Voltage vs. Temperature
336
332
330
328
326
324
322
2.00
0.00
-2.00
-4.00
-6.00
-8.00
-10.00
320
-50
0
50
100
-50
150
0
Sensivity vs. Temperature
150
1.5
1
Sensivity Error (%)
133
Sensivity (mV/A)
100
Sensivity Error vs. Temperature
134
132
131
130
129
128
0.5
0
-0.5
-1
-1.5
-2
-2.5
-3
-3.5
127
-4
-50
0
50
100
150
-50
0
Temperature (°C)
50
100
150
Temperature (°C)
Total Error at IPR(max) vs. Temperature
Nonlinearity vs. Temperature
1
1
0.8
0.5
0.6
0
0.4
-0.5
Total Error (%)
Nonlinearity (%)
50
Temperature (°C)
Temperature (°C)
0.2
0
-0.2
-0.4
-1
-1.5
-2
-2.5
-0.6
-3
-0.8
-3.5
-4
-1
-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
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 Package
ACS725
xLLCTR-20AB
Offset Voltage vs. Temperature
Zero Current Output Voltage vs. Temperature
6
1655
5
1654
4
Offset Voltage (mV)
1656
VIOUT(Q) (mV)
1653
1652
1651
1650
1649
1648
3
2
1
0
-1
-2
-3
1647
1646
-4
1645
-5
-50
0
50
100
-50
150
0
100
150
Temperature (ºC)
Temperature (ºC)
Sensitivity vs. Temperature
Sensitivity Error vs. Temperature
67
1
66
0
Sensitivity Error (%)
Sensitivity (mV/A)
50
66
65
65
64
-1
-2
-3
-4
64
63
-5
-50
0
50
100
-50
150
0
Temperature (ºC)
50
100
150
Temperature (ºC)
Nonlinearity vs. Temperature
Total Error at IPR(max) vs. Temperature
1
1.00
0.80
0
0.40
Total Error (%)
Nonlinearity (%)
0.60
0.20
0.00
-0.20
-0.40
-1
-2
-3
-0.60
-4
-0.80
-1.00
-5
-50
0
50
100
150
-50
Temperature (ºC)
+3 Sigma
0
50
100
150
Temperature (ºC)
Average
-3 Sigma
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
11
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 Package
ACS725
xLLCTR-30AB
Offset Voltage vs. Temperature
1656
6
1654
4
Offset Voltage (mV)
VIOUT(Q) (mV)
Zero Current Output Voltage vs. Temperature
1652
1650
1648
1646
2
0
-2
-4
1644
-6
-50
0
50
100
150
-50
0
Temperature (ºC)
Sensitivity vs. Temperature
100
150
Sensitivity Error vs. Temperature
45
1
44
0
Sensitivity Error (%)
Sensitivity (mV/A)
50
Temperature (ºC)
44
43
43
-1
-2
-3
-4
42
42
-5
-50
0
50
100
150
-50
0
Temperature (ºC)
50
100
150
Temperature (ºC)
Total Error at IPR(max) vs. Temperature
Nonlinearity vs. Temperature
1
1.00
0.80
0
0.40
Total Error (%)
Nonlinearity (%)
0.60
0.20
0.00
-0.20
-0.40
-0.60
-1
-2
-3
-4
-0.80
-5
-1.00
-50
0
50
100
-50
150
50
100
150
Temperature (ºC)
Temperature (ºC)
+3 Sigma
0
Average
-3 Sigma
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
12
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 Package
ACS725
xLLCTR-40AB
Offset Voltage vs. Temperature
1656
6
1654
4
Offset Voltage (mV)
VIOUT(Q) (mV)
Zero Current Output Voltage vs. Temperature
1652
1650
1648
1646
2
0
-2
-4
1644
-6
-50
0
50
100
150
-50
0
Temperature (ºC)
Sensitivity vs. Temperature
100
150
Sensitivity Error vs. Temperature
2
33
33
1
Sensitivity Error (%)
33
Sensitivity (mV/A)
50
Temperature (ºC)
33
33
32
32
32
32
0
-1
-2
-3
-4
32
31
-5
-50
0
50
100
150
-50
0
Temperature (ºC)
50
100
150
Temperature (ºC)
Nonlinearity vs. Temperature
Total Error at IPR(max) vs. Temperature
2
1.00
0.80
1
0.40
Total Error (%)
Nonlinearity (%)
0.60
0.20
0.00
-0.20
-0.40
0
-1
-2
-3
-0.60
-4
-0.80
-1.00
-5
-50
0
50
100
150
-50
Temperature (ºC)
+3 Sigma
0
50
100
150
Temperature (ºC)
Average
-3 Sigma
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
13
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 Package
ACS725
APPLICATION INFORMATION
Estimating Total Error vs. Sensed Current
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:
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
Total Error (% of Current Measured)
ETOT (IP) = ESENS +
(
100 × VOE
Sens × IP
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 vs. sensed current
(IP) is below for the ACS725LLCTR-20AB. As expected, as one
goes towards zero current, the error in percent goes towards infinity due to division by zero.
2
)
8
6
-40ºC + 3σ
4
-40ºC – 3σ
2
25ºC + 3σ
0
25ºC – 3σ
-2
85ºC + 3σ
-4
85ºC – 3σ
-6
-8
0
5
10
15
20
Current (A)
Figure 1: Predicted Total Error as a Function of the Sensed Current for the ACS725LLCTR-20AB
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
14
ACS725
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 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 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.
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:
VIOUT(IPR(max)) – VIOUT(Q)
ELIN = 1–
• 100(%)
2 • VIOUT(IPR(max)/2) – VIOUT(Q)
Increasing
VIOUT (V)
Accuracy at
25°C Only
IPR(min)
ETOT (IP) =
+IP (A)
VIOUT(Q)
–IP (A)
Full Scale IP
IPR(max)
0A
Accuracy at
25°C Only
Decreasing
VIOUT (V)
Accuracy Across
Temperature
Figure 1: Output Voltage versus Sensed Current
+ETOT
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 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
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.
Accuracy Across
Temperature
Across Temperature
25°C Only
–IP
+IP
VIOUT_ideal(IP) – VIOUT (IP)
• 100 (%)
Sensideal(IP) • 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 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 .
–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
15
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 Package
ACS725
Sensitivity Ratiometry Coefficient (SENS_RAT_COEF). The
coefficient defining how the sensitivity scales with VCC. The
ideal coefficient is 1, meaning the sensitivity scales proportionally with VCC. A 10% increase in VCC results in a 10% increase
in sensitivity. A coefficient of 1.1 means that the sensitivity
increases by 10% more than the ideal proportionality case. This
means that a 10% increase in VCC results in an 11% increase in
sensitivity. This relationship is described by the following equation:
Sens(VCC ) = Sens(3.3 V) 1 +
(VCC – 3.3 V) • SENS_RAT_COEF
3.3 V
This can be rearranged to define the sensitivity ratiometry coefficient as:
SENS_RAT_COEF =
Sens(VCC )
3.3 V
–1 •
(VCC – 3.3 V)
Sens(3.3 V)
Zero Current Output Ratiometry Coefficient (QVO_RAT_
COEF). The coefficient defining how the zero current output
voltage scales with VCC. The ideal coefficient is 1, meaning the
output voltage scales proportionally with VCC, always being
equal to VCC/2. A coefficient of 1.1 means that the zero current
output voltage increases by 10% more than the ideal proportionality case. This means that a 10% increase in VCC results in an
11% increase in the zero current output voltage. This relationship
is described by the following equation:
VIOUTQ(VCC ) = VIOUTQ(3.3 V) 1 +
(VCC – 3.3 V) • QVO_RAT_COEF
3.3 V
This can be rearranged to define the zero current output ratiometry coefficient as:
QVO_RAT_COEF =
VIOUTQ(VCC )
3.3 V
–1 •
(V
VIOUTQ(3.3 V)
CC – 3.3 V)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
16
ACS725
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a 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 IC
reaches 10% of its full scale value, and b) when it reaches 90%
of its full scale value. 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 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.
(%)
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 primary current signal reaches 90% of its final value, and b)
when the device reaches 90% of its output corresponding to the
applied current.
(%)
90
Primary Current
VIOUT
Response Time, tRESPONSE
0
Figure 5: Response Time (tRESPONSE)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
t
17
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 Package
ACS725
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
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
18
ACS725
Automotive-Grade, Galvanically Isolated Current Sensor IC
With Common-Mode Field Rejection in a Small Footprint SOIC8 Package
Document Revision History
Revision
Change
Pages
Responsible
Date
All
A. Latham
January 19, 2015
–
Initial Release
1
Added ACS725LLCTR-20AU-T to Selection Guide and Performance
Characteristics charts, and corrected Sensitivity Error;
added xLLCTR-20AU Characteristic Performance charts.
2, 6-8,
10
A. Latham
September 28, 2015
2
Added ACS725LLCTR-30AU-T to Selection Guide and Performance
Characteristics charts.
2, 8
A. Latham
December 11, 2015
Copyright ©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
19
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