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ACS725 Schematic ( PDF Datasheet ) - Allegro MicroSystems

Teilenummer ACS725
Beschreibung Galvanically Isolated Current Sensor IC
Hersteller Allegro MicroSystems
Logo Allegro MicroSystems Logo 




Gesamt 17 Seiten
ACS725 Datasheet, Funktion
ACS725
Automotive Grade, Galvanically Isolated Current Sensor IC
With Common Mode Field Rejection in a Small Footprint SOIC8 Package
FEATURES AND BENEFITS
• 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 120KHz 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
Continued on the next page…
Package: 8-Pin SOIC (suffix LC)
Tytpeested
TÜV America
Certificate Number:
U8V 14 11 54214 032
CB 14 11 54214 031
CB Certificate Number:
US-22334-A2-UL
Approximate Scale 1:1
DESCRIPTION
The AllegroACS725 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.
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…
ACS725-DS
1
IP+
VCC 8
+IP ACS725
2
IP+
7
VIOUT
IP
3
IP–
–IP
FILTER 6
4
IP–
GND 5
CF
1 nF
CLOAD
CBYPASS
0.1 µF
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.
Typical Application






ACS725 Datasheet, Funktion
ACS725
Automotive Grade, Galvanically Isolated Current Sensor IC
With Common Mode Field Rejection in a Small Footprint SOIC8 Package
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
Sens
VIOUT(Q)
IPR(min) < IP < IPR(max)
Unidirectional; IP = 0 A
0 – 10 A
– 264 – mV/A
Vcc x
0.1
V
Accuracy Performance
Total Output Error2
ETOT
IP = IPR(max); TA = 25°C to 150ºC
IP = IPR(max); TA = –40°C to 25ºC
Total Output Error Components3 ETOT = ESENS + 100 x VOE/(Sens x IP)
Sensitivity Error
Esens
IP = IPR(max); TA = 25°C to 150ºC
IP = IPR(max); TA = –40°C to 25ºC
Offset Voltage
VOE
IP = 0 A; TA = 25°C to 150ºC
IP = 0 A; TA = –40°C to 25ºC
Lifetime Drift Characteristics
-2.5 ±0.9
-6 ±4
-2 ±0.9
-5.5 ±4
–15 ±5
–30 ±15
2.5
6
2
5.5
15
30
%
%
mV
Sensitivity Error Lifetime Drift
Total Output Error Lifetime
Drift
Esens_drift
Etot_drift
– ±2 – %
– ±2 – %
1 Typical values with ± are 3 sigma values
2 Percentage of IP , with IP = IPR(max).
3 A single part will not have both the maximum/minimum sensitivity error and maximum/minimum 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.
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
Nominal Performance
Current Sensing Range
Sensitivity
Zero Current Output Voltage
IPR
Sens
VIOUT(Q)
IPR(min) < IP < IPR(max)
Bidirectional; IP = 0 A
-20 - 20 A
- 66 - mV/A
-
Vcc x
0.5
-
V
Accuracy Performance
Total Output Error2
ETOT
IP = IPR(max); TA = 25°C to 150ºC
IP = IPR(max); TA = –40°C to 25ºC
Total Output Error Components3 ETOT = ESENS + 100 x VOE/(Sens x IP)
Sensitivity Error
Esens
IP = IPR(max); TA = 25°C to 150ºC
IP = IPR(max); TA = –40°C to 25ºC
Offset Voltage
VOE
IP = 0 A; TA = 25°C to 150ºC
IP = 0 A; TA = –40°C to 25ºC
Lifetime Drift Characteristics
-2 ±0.8
-6 ±4
-1.5 ±0.8
-5.5 ±4
-10 ±4
-30 ±5
2
6
1.5
5
10
30
%
%
mV
Sensitivity Error Lifetime Drift
Total Output Error Lifetime
Drift
Esens_drift
Etot_drift
– ±2 – %
– ±2 – %
1 Typical values with ± are 3 sigma values
2 Percentage of IP , with IP = IPR(max).
3 A single part will not have both the maximum/minimum sensitivity error and maximum/minimum 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.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
6

6 Page









ACS725 pdf, datenblatt
ACS725
Automotive Grade, Galvanically Isolated Current Sensor IC
With Common Mode Field Rejection in a Small Footprint SOIC8 Package
APPLICATION INFORMATION
Estimating Total Error vs. 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 compo-
nents of Total Error, Sensitivity Error and Offset Voltage. The
±3 sigma value for Total Error (ETOT) as a function of the sensed
current (IP) is estimated as:
( )ETOT (IP) =
E +2
SENS
100 × VOE
Sens × IP
2
Here, ESENS and VOE are the ±3 sigma values for those error
terms. If there is an average sensitivity error or average offset
voltage, then the average Total Error is estimated as:
E (I ) = E +TOTAVG P
SENSAVG
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 Sensitiv-
ity 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 infin-
ity due to division by zero.
8
6
4 -40ºC + 3σ
-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
12

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