ACS715
Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor
with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor
Features and Benefits
Description
▪
▪
▪
▪
▪
▪
▪
▪
▪
▪
▪
▪
▪
▪
▪
▪
The Allegro® ACS715 provides economical and precise
solutions for DC current sensing in automotive 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.
Low-noise analog signal path
Device bandwidth is set via the FILTER pin
5 μs output rise time in response to step input current
80 kHz bandwidth
Total output error 1.5% typical at TA = 25°C
Small footprint, low-profile SOIC8 package
1.2 mΩ internal conductor resistance
2.1 kVRMS minimum isolation voltage from pins 1-4 to pins 5-8
5.0 V, single supply operation
133 to 185 mV/A output sensitivity
Output voltage proportional to DC currents
Factory-trimmed for accuracy
Extremely stable output offset voltage
Nearly zero magnetic hysteresis
Ratiometric output from supply voltage
Operating temperature range, –40°C to 150°C
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 signal 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 (>VIOUT(Q))
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 thickness of the copper conductor allows survival
Package: 8 Lead SOIC (suffix LC)
Continued on the next page…
Approximate Scale 1:1
Typical Application
+5 V
1
IP+
VCC
2
IP+ VIOUT
3
IP– FILTER
IP
8
7
VOUT
CBYP
0.1 μF
ACS715
4
IP–
GND
6
5
CF
Application 1. The ACS715 outputs an analog signal, VOUT .
that varies linearly with the unidirectional DC primary sensed
current, IP , within the range specified. CF is recommended for
noise management, with values that depend on the application.
ACS715-DS
Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor
with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor
ACS715
Description (continued)
of the device at up to 5× overcurrent conditions. The terminals of
the conductive path are electrically isolated from the sensor leads
(pins 5 through 8). This allows the ACS715 current sensor to be
used in applications requiring electrical isolation without the use
of opto-isolators or other costly isolation techniques.
The ACS715 is provided in a small, 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
Optimized Range, IP
(A)
Sensitivity, Sens
(Typ) (mV/A)
ACS715ELCTR-20A-T
0 to 20
185
ACS715ELCTR-30A-T
0 to 30
133
ACS715LLCTR-20A-T
0 to 20
185
ACS715LLCTR-30A-T
0 to 30
133
TA
(°C)
Packing*
–40 to 85
Tape and reel, 3000 pieces/reel
–40 to 150
*Contact Allegro for additional packing options.
Absolute Maximum Ratings
Characteristic
Symbol
Notes
Rating
Units
Supply Voltage
VCC
8
V
Reverse Supply Voltage
VRCC
–0.1
V
Output Voltage
VIOUT
8
V
Reverse Output Voltage
VRIOUT
–0.1
V
Reinforced Isolation Voltage
VISO
Rated Input Voltage
Vworking
Output Current Source
Pins 1-4 and 5-8; 60 Hz, 1 minute, TA=25°C
2100
V
Voltage applied to leadframe (Ip+ pins)
184
V AC Max
IOUT(Source)
3
mA
IOUT(Sink)
10
mA
Output Current Sink
Overcurrent Transient Tolerance
Nominal Operating Ambient Temperature
Maximum Junction Temperature
Storage Temperature
TÜV America
Certificate Number:
U8V 06 05 54214 010
IP
1 pulse, 100 ms
100
A
Range E
–40 to 85
ºC
Range L
–40 to 150
ºC
TJ(max)
165
ºC
Tstg
–65 to 170
ºC
TA
Parameter
Specification
Fire and Electric Shock
CAN/CSA-C22.2 No. 60950-1-03
UL 60950-1:2003
EN 60950-1:2001
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
2
Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor
with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor
ACS715
Functional Block Diagram
+5 V
VCC
(Pin 8)
Hall Current
Drive
IP+
(Pin 1)
Sense Temperature
Coefficient Trim
Dynamic Offset
Cancellation
IP+
(Pin 2)
IP–
(Pin 3)
Signal
Recovery
VIOUT
(Pin 7)
Sense
Trim
IP–
(Pin 4)
0 Ampere
Offset Adjust
GND
(Pin 5)
FILTER
(Pin 6)
Pin-out Diagram
IP+
1
8
VCC
IP+
2
7
VIOUT
IP–
3
6
FILTER
IP–
4
5
GND
Terminal List Table
Number
Name
1 and 2
IP+
Input terminals for current being sensed; fused internally
3 and 4
IP–
Output terminals for current being sensed; fused internally
5
GND
6
FILTER
7
VIOUT
8
VCC
Description
Signal ground terminal
Terminal for external capacitor that sets bandwidth
Analog output signal
Device power supply terminal
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
3
ACS715
Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor
with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor
COMMON OPERATING CHARACTERISTICS1 over full range of TA, and VCC = 5 V, unless otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
4.5
5.0
5.5
V
–
10
13
mA
ELECTRICAL CHARACTERISTICS
Supply Voltage
VCC
Supply Current
ICC
VCC = 5.0 V, output open
Output Capacitance Load
CLOAD
VIOUT to GND
–
–
10
nF
Output Resistive Load
RLOAD
VIOUT to GND
4.7
–
–
kΩ
mΩ
Primary Conductor Resistance
RPRIMARY
TA = 25°C
–
1.2
–
Rise Time
tr
IP = IP(max), TA = 25°C, COUT = 10 nF
–
5
–
μs
Frequency Bandwidth
f
–3 dB, TA = 25°C; IP is 10 A peak-to-peak
–
80
–
kHz
±1.5
–
%
Nonlinearity
ELIN
Over full range of IP , IP applied for 5 ms
–
Symmetry
ESYM
Over full range of IP , IP applied for 5 ms
98
100
102
%
Unidirectional; IP = 0 A, TA = 25°C
–
VCC ×
0.1
–
V
Output reaches 90% of steady-state level, no capacitor on
FILTER pin; TJ = 25; 20 A present on leadframe
–
35
–
μs
12
–
G/A
Zero Current Output Voltage
Power-On Time
VIOUT(Q)
tPO
Magnetic Coupling2
Internal Filter Resistance3
–
RF(INT)
1.7
kΩ
1Device
may be operated at higher primary current levels, IP, and ambient, TA , and internal leadframe temperatures, TA , provided that the Maximum
Junction Temperature, TJ(max), is not exceeded.
21G = 0.1 mT.
3R
F(INT) forms an RC circuit via the FILTER pin.
COMMON THERMAL CHARACTERISTICS1
Operating Internal Leadframe Temperature
TA
Min.
Typ.
Max.
E range
–40
–
85
Units
°C
L range
–40
–
150
°C
Value
Units
Junction-to-Lead Thermal Resistance2
RθJL
Mounted on the Allegro ASEK 715 evaluation board
5
°C/W
Junction-to-Ambient Thermal Resistance2,3
RθJA
Mounted on the Allegro 85-0322 evaluation board, includes the power
consumed by the board
23
°C/W
1Additional
thermal information is available on the Allegro website.
evaluation board has 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. 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.
3R
θJA values shown in this table are typical values, measured on the Allegro evaluation board. The actual thermal performance depends on the actual
application board design, the airflow in the application, and thermal interactions between the sensor and surrounding components through the PCB and
the ambient air. To improve thermal performance, see our applications material on the Allegro website.
2The Allegro
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
4
ACS715
Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor
with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor
x20A PERFORMANCE CHARACTERISTICS over Range E: TA = –40°C to 85°C1, CF = 1 nF, and VCC = 5 V, unless otherwise specified
Characteristic
Optimized Accuracy Range
Sensitivity
Noise
Symbol
Sens
VNOISE(PP)
Zero Current Output Slope
Sensitivity Slope
Test Conditions
Min.
Typ.
Max.
0
–
20
A
178
185
190
mV/A
Peak-to-peak, TA = 25°C, 2 kHz external filter, 185 mV/A programmed Sensitivity, CF = 47 nF, COUT = 10 nF, 2 kHz bandwidth
–
21
–
mV
mV/°C
IP
∆IOUT(Q)
∆Sens
Over full range of IP , IP applied for 5ms; TA = 25°C
Units
TA = –40°C to 25°C
–
0.08
–
TA = 25°C to 150°C
–
0.16
–
mV/°C
TA = –40°C to 25°C
–
0.035
–
mV/A/°C
TA = 25°C to 150°C
Electrical Offset Voltage
VOE
IP = 0 A
Total Output Error2
ETOT
IP = 20 A , IP applied for 5 ms; TA = 25°C
–
0.019
–
mV/A/°C
–40
–
40
mV
–
±1.5
–
%
1Device
may be operated at higher primary current levels, IP, and ambient temperatures, TA, provided that the Maximum Junction Temperature,
TJ(max), is not exceeded.
2Percentage of I , with I = 20 A. Output filtered.
P
P
x20A PERFORMANCE CHARACTERISTICS over Range L: TA = –40°C to 150°C1, CF = 1 nF, and VCC = 5 V, unless otherwise specified
Characteristic
Optimized Accuracy Range
Sensitivity
Noise
Zero Current Output Slope
Sensitivity Slope
Electrical Offset Voltage
Total Output Error2
Symbol
Test Conditions
IP
Sens
VNOISE(PP)
∆IOUT(Q)
∆Sens
VOE
ETOT
Over full range of IP , IP applied for 5ms; TA = 25°C
Over full range of IP, TA = –40°C to 150°C
Min.
Typ.
Max.
0
–
20
Units
A
–
185
–
mV/A
161
–
194
mV/A
Peak-to-peak, TA = 25°C, 2 kHz external filter, 185 mV/A programmed Sensitivity, CF = 47 nF, COUT = 10 nF, 2 kHz bandwidth
–
21
–
mV
mV/°C
TA = –40°C to 25°C
–
0.08
–
TA = 25°C to 150°C
–
0.16
–
mV/°C
TA = –40°C to 25°C
–
0.035
–
mV/A/°C
TA = 25°C to 150°C
–
0.019
–
mV/A/°C
–60
–
60
mV
IP = 20 A , IP applied for 5 ms; TA = 25°C
–
±1.5
–
%
IP = 20 A , IP applied for 5 ms; TA = –40° to 150°C
–6
–
6
%
IP = 0 A
1Device
may be operated at higher primary current levels, IP, and ambient temperatures, TA, provided that the Maximum Junction Temperature,
TJ(max), is not exceeded.
2Percentage of I , with I = 20 A. Output filtered.
P
P
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
5
ACS715
Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor
with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor
x30A PERFORMANCE CHARACTERISTICS over Range E: TA = –40°C to 85°C1, CF = 1 nF, and VCC = 5 V, unless otherwise specified
Characteristic
Optimized Accuracy Range
Sensitivity
Noise
Symbol
Sens
VNOISE(PP)
Zero Current Output Slope
Sensitivity Slope
Test Conditions
Min.
Typ.
Max.
0
–
30
A
129
133
137
mV/A
Peak-to-peak, TA = 25°C, 2 kHz external filter, 133 mV/A programmed Sensitivity, CF = 47 nF, COUT = 10 nF, 2 kHz bandwidth
–
15
–
mV
mV/°C
IP
∆IOUT(Q)
∆Sens
Over full range of IP , IP applied for 5ms; TA = 25°C
Units
TA = –40°C to 25°C
–
0.06
–
TA = 25°C to 150°C
–
0.1
–
mV/°C
TA = –40°C to 25°C
–
0.007
–
mV/A/°C
TA = 25°C to 150°C
Electrical Offset Voltage
VOE
IP = 0 A
Total Output Error2
ETOT
IP = 30 A , IP applied for 5 ms; TA = 25°C
–
–0.025
–
mV/A/°C
–30
–
30
mV
–
±1.5
–
%
1Device
may be operated at higher primary current levels, IP, and ambient temperatures, TA, provided that the Maximum Junction Temperature,
TJ(max), is not exceeded.
2Percentage of I , with I = 30 A. Output filtered.
P
P
x30A PERFORMANCE CHARACTERISTICS over Range L: TA = –40°C to 150°C1, CF = 1 nF, and VCC = 5 V, unless otherwise specified
Characteristic
Optimized Accuracy Range
Sensitivity
Noise
Zero Current Output Slope
Sensitivity Slope
Electrical Offset Voltage
Total Output Error2
Symbol
Test Conditions
Min.
IP
Sens
VNOISE(PP)
∆IOUT(Q)
∆Sens
VOE
ETOT
Over full range of IP , IP applied for 5ms; TA = 25°C
Over full range of IP, TA = –40°C to 150°C
Typ.
Max.
Units
0
–
30
A
–
133
–
mV/A
125
–
137
mV/A
Peak-to-peak, TA = 25°C, 2 kHz external filter, 133 mV/A programmed Sensitivity, CF = 47 nF, COUT = 10 nF, 2 kHz bandwidth
–
15
–
mV
mV/°C
TA = –40°C to 25°C
–
0.06
–
TA = 25°C to 150°C
–
0.1
–
mV/°C
TA = –40°C to 25°C
–
0.007
–
mV/A/°C
TA = 25°C to 150°C
–
–0.025
–
mV/A/°C
mV
IP = 0 A
–40
–
40
IP = 30 A , IP applied for 5 ms; TA = 25°C
–
±1.5
–
%
IP = 30 A , IP applied for 5 ms; TA = –40° to 150°C
–5
–
5
%
1Device may be operated at higher primary current levels, I , and ambient temperatures, T , provided that the Maximum Junction Temperature,
P
A
TJ(max), is not exceeded.
2Percentage of I , with I = 30 A. Output filtered.
P
P
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
6
Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor
with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor
ACS715
Characteristic Performance
IP = 20 A, unless otherwise specified
Mean Supply Current versus Ambient Temperature
Supply Current versus Supply Voltage
10.5
11.2
10.4
11.0
VCC = 5 V
10.8
10.2
VCC = 5 V
ICC (mA)
Mean ICC (mA)
10.3
10.1
10.0
9.9
10.6
10.4
10.2
9.8
10.0
9.7
9.8
9.6
-50
-25
0
25
50
75
100
125
9.6
4.5
150
4.6
4.7
4.8
4.9
TA (°C)
Magnetic Offset versus Ambient Temperature
5.5
0.25
–1.5
–2.0
–2.5
ELIN (%)
IOM (mA)
5.4
0.30
–1.0
VCC = 5 V; IP = 0 A,
After excursion to 20 A
–3.0
–3.5
0.20
0.15
0.10
–4.0
0.05
–4.5
–5.0
-50
-25
0
25
50
75
100
125
0
–50
150
–25
0
25
75
50
100
125
150
TA (°C)
TA (°C)
Mean Total Output Error versus Ambient Temperature
Sensitivity versus Ambient Temperature
10
188
8
187
6
Sens (mV/A)
4
ETOT (%)
5.3
Nonlinearity versus Ambient Temperature
–0.5
2
0
–2
–4
186
185
184
183
–6
–8
–50
182
–25
0
25
75
50
100
125
150
–50
–25
0
25
TA (°C)
Output Voltage versus Sensed Current
4.5
4.0
Sens (mV/A)
VCC = 5 V
3.5
3.0
TA (°C)
–40
–20
25
85
125
2.5
2.0
1.5
1.0
0.5
0
0
5
10
15
20
25
30
200.00
198.00
196.00
194.00
192.00
190.00
188.00
186.00
184.00
182.00
180.00
178.00
176.00
174.00
100
125
150
35
Sensitivity versus Sensed Current
TA (°C)
–40
25
85
150
0
5
10
IP (A)
0 A Output Voltage versus Ambient Temperature
15
Ip (A)
20
25
0 A Output Voltage Current versus Ambient Temperature
5250
–19.75
5200
–19.80
IP = 0 A
5100
5050
–19.90
–19.95
5000
–20.00
4950
–20.05
-25
0
25
IP = 0 A
–19.85
IOUT(Q) (A)
5150
4900
-50
75
50
TA (°C)
5.0
VIOUT (V)
5.2
0.35
0
VIOUT(Q) (mV)
5.0 5.1
VCC (V)
50
TA (°C)
75
100
125
150
–20.10
-50
-25
0
25
50
75
100
125
150
TA (°C)
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
7
Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor
with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor
ACS715
Characteristic Performance
IP = 30 A, unless otherwise specified
Mean Supply Current versus Ambient Temperature
Supply Current versus Supply Voltage
10.1
10.8
10.0
10.6
ICC (mA)
Mean ICC (mA)
9.9
VCC = 5 V
90.8
9.7
10.4
10.0
9.6
9.8
9.5
9.6
9.4
-50
-25
0
25
50
75
100
125
VCC = 5 V
10.2
9.4
4.5
150
4.7
4.6
4.8
4.9
TA (°C)
–0.5
5.5
0.25
–1.5
–2.5
ELIN (%)
–2.0
VCC = 5 V; IP = 0 A,
After excursion to 20 A
–3.0
–3.5
0.20
VCC = 5 V
0.15
0.10
–4.0
0.05
–4.5
–5.0
-50
-25
0
25
50
75
100
125
0
–50
150
–25
0
6
133.0
Sens (mV/A)
133.5
4
2
0
132.0
131.5
131.0
–4
130.5
–6
130.0
25
75
50
100
125
129.5
–50
150
–25
0
25
Output Voltage versus Sensed Current
Sens (mV/A)
4.0
VCC = 5 V
3.0
TA (°C)
–40
–20
25
85
125
2.5
2.0
1.5
1.0
0.5
0
10
15
20
150
25
30
TA (°C)
–40
25
85
150
0
35
5
10
15
IP (A)
0 A Output Voltage versus Ambient Temperature
25
20
Ip (A)
30
35
0 A Output Voltage Current versus Ambient Temperature
5140
0
5120
–5
5100
–10
IP = 0 A
5080
IOUT(Q) (A)
5060
5040
5020
5000
IP = 0 A
–15
–20
–25
4980
–30
4960
4940
-50
125
Sensitivity versus Sensed Current
140
139
138
137
136
135
134
133
132
131
130
129
128
127
126
125
4.5
5
100
TA (°C)
5.0
0
75
50
TA (°C)
3.5
150
132.5
–2
0
125
Sensitivity versus Ambient Temperature
8
–25
100
TA (°C)
Mean Total Output Error versus Ambient Temperature
–8
–50
75
50
25
TA (°C)
ETOT (%)
5.4
0.30
–1.0
VIOUT (V)
5.3
0.35
0
VIOUT(Q) (mV)
5.2
Nonlinearity versus Ambient Temperature
Magnetic Offset versus Ambient Temperature
IOM (mA)
5.0 5.1
VCC (V)
-25
0
25
50
TA (°C)
75
100
125
150
–35
-50
-25
0
25
50
75
100
125
150
TA (°C)
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
8
ACS715
Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor
with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor
Definitions of Accuracy Characteristics
Sensitivity (Sens). The change in sensor output in response to a
1 A change through the primary conductor. The sensitivity is the
product of the magnetic circuit sensitivity (G / A) 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.
Noise (VNOISE). The product of the linear IC amplifier gain
(mV/G) and the noise floor for the Allegro Hall effect linear IC
(≈1 G). The noise floor is derived from the thermal and shot
noise observed in Hall elements. Dividing the noise (mV) by the
sensitivity (mV/A) provides the smallest current that the device is
able to resolve.
Linearity (ELIN). The degree to which the voltage output from
the sensor varies in direct proportion to the primary current
through its full-scale amplitude. Nonlinearity in the output can be
attributed to the saturation of the flux concentrator approaching
the full-scale current. The following equation is used to derive the
linearity:
{ [
100 1–
Δ gain × % sat ( VIOUT_full-scale amperes – VIOUT(Q) )
2 (VIOUT_half-scale amperes – VIOUT(Q) )
[{
Accuracy is divided into four areas:
• 0 A at 25°C. Accuracy of sensing zero current flow at 25°C,
without the effects of temperature.
• 0 A over Δ temperature. Accuracy of sensing zero current
flow including temperature effects.
• Full-scale current at 25°C. Accuracy of sensing the full-scale
current at 25°C, without the effects of temperature.
• Full-scale current over Δ temperature. Accuracy of sensing fullscale current flow including temperature effects.
Ratiometry. The ratiometric feature means that its 0 A output,
VIOUT(Q), (nominally equal to VCC/2) and sensitivity, Sens, are
proportional to its supply voltage, VCC . The following formula is
used to derive the ratiometric change in 0 A output voltage,
ΔVIOUT(Q)RAT (%).
100
100
VCC / 5 V
SensVCC / Sens5V
‰
VCC / 5 V
Output Voltage versus Sensed Current
Accuracy at 0 A and at Full-Scale Current
Increasing VIOUT(V)
Accuracy
Over $Temp erature
Accuracy
25°C Only
Electrical offset voltage (VOE). The deviation of the device output from its ideal quiescent value of VCC / 2 due to nonmagnetic
causes. To convert this voltage to amperes, divide by the device
sensitivity, Sens.
Accuracy (ETOT). The accuracy represents the maximum deviation of the actual output from its ideal value. This is also known
as the total ouput error. The accuracy is illustrated graphically in
the output voltage versus current chart at right.
The ratiometric change in sensitivity, ΔSensRAT (%), is defined as:
where VIOUT_full-scale amperes = the output voltage (V) when the
sensed current approximates full-scale ±IP .
Quiescent output voltage (VIOUT(Q)). The output of the sensor
when the primary current is zero. For a unipolar supply voltage,
it nominally remains at VCC ⁄ 2. Thus, VCC = 5 V translates into
VIOUT(Q) = 2.5 V. Variation in VIOUT(Q) can be attributed to the
resolution of the Allegro linear IC quiescent voltage trim and
thermal drift.
VIOUT(Q)VCC / VIOUT(Q)5V
Average
VIOUT
Accuracy
Over $Temp erature
Accuracy
25°C Only
30 A
–IP (A)
+IP (A)
Full Scale
0A
Decreasing VIOUT(V)
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
9
Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor
with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor
ACS715
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.
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. The rise time to a step response is used to
derive the bandwidth of the current sensor, 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.
Primary Current
I (%)
90
Transducer Output
10
0
t
Noise vs. Filter Cap
Power on Time versus External Filter Capacitance
200
180
160
140
120
100
80
60
40
20
0
10000
IP =5 A
IP =0 A
0
10
20
CF (nF)
30
40
100
10
1
0.01
50
1000
0
1
4.7
10
22
47
100
220
470
800
600
}
Expanded in chart at right
200
0
0
100
200
300
CF (nF)
400
0.1
1
CF (nF)
10
100
1000
Rise Time versus External Filter Capacitance
CF (nF)
500
tr (μs)
6.6
7.7
17.4
32.1
68.2
88.2
291.3
623.0
1120.0
tr(μs)
tr(μs)
Rise Time versus External Filter Capacitance
1200
400
Noise versus External Filter Capacitance
1000
Noise(p-p) (mA)
tPO (μs)
Rise Time, tr
400
350
300
250
200
150
100
50
0
0
25
50
75
CF (nF)
100
125
150
10
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor
with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor
ACS715
Chopper Stabilization Technique
This technique is made possible through the use of a BiCMOS
process that allows the use of low-offset and low-noise amplifiers
in combination with high-density logic integration and sample
and hold circuits.
Regulator
Clock/Logic
Low-Pass
Filter
Hall Element
Sample and
Hold
Chopper Stabilization is an innovative circuit technique that is
used to minimize the offset voltage of a Hall element and an associated on-chip amplifier. Allegro patented a Chopper Stabilization technique that nearly eliminates Hall IC output drift induced
by temperature or package stress effects. This offset reduction
technique is based on a signal modulation-demodulation process.
Modulation is used to separate the undesired dc offset signal from
the magnetically induced signal in the frequency domain. Then,
using a low-pass filter, the modulated dc offset is suppressed
while the magnetically induced signal passes through the filter.
As a result of this chopper stabilization approach, the output
voltage from the Hall IC is desensitized to the effects of temperature and mechanical stress. This technique produces devices that
have an extremely stable Electrical Offset Voltage, are immune to
thermal stress, and have precise recoverability after temperature
cycling.
Amp
Concept of Chopper Stabilization Technique
Typical Applications
+5 V
+5 V
CBYP
0.1 μF
1
2
IP
IP+
VCC
IP+ VIOUT
8
1
7
VOUT
4
IP– FILTER
IP–
GND
4
3
6
5
R1
100 kΩ
RPU
100 kΩ
R2
100 kΩ
ACS715
3
CBYP
0.1 μF
R1
33 kΩ
–
+
5
1
2
Fault
IP
2 U1
LMV7235
IP+ VIOUT
CF
4
IP– FILTER
IP–
D1
1N914
GND
2
Application 4. Control circuit for MOSFET ORing.
3
4
+
3
–
VOUT
4
C1
1000 pF
R3
3.3 kΩ
6
5
LM321
5
2
RF
1 kΩ
CF
0.01 μF
+5 V
IP+
VCC
IP+ VIOUT
IP– FILTER
IP–
GND
1
+
7 VOUT
VREF
U1
LMC6772
–
2
3
CF
IP+
VCC
IP+ VIOUT
CBYP
0.1 μF
8
+
7 VOUT
VREF
ACS715
IP2
6
5
+5 V
VS2
CBYP
0.1 μF
8
ACS715
IP1
7
1
Application 3. This configuration increases gain to 610 mV/A
(tested using the ACS712ELC-05A).
VS1
1
R2
100 kΩ
ACS715
3
Application 2. 10 A Overcurrent Fault Latch. Fault threshold
set by R1 and R2. This circuit latches an overcurrent fault
and holds it until the 5 V rail is powered down.
VCC
IP+
8
4
IP– FILTER
IP–
GND
–
6
5
CF
Q4
2N7002
Q3
2N7002
Q1
FDS6675a
U2
LMC6772
Q2
FDS6675a
R3
10 kΩ
R4
10 kΩ
R2
100 kΩ
R1
100 kΩ
LOAD
11
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor
with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor
ACS715
Improving Sensing System Accuracy Using the FILTER Pin
In low-frequency sensing applications, it is often advantageous to
add a simple RC filter to the output of the sensor. Such a lowpass filter improves the signal-to-noise ratio, and therefore the
resolution, of the sensor output signal. However, the addition of
an RC filter to the output of a sensor IC can result in undesirable
sensor output attenuation — even for dc signals.
Signal attenuation, ∆VATT , is a result of the resistive divider
effect between the resistance of the external filter, RF (see Application 5), and the input impedance and resistance of the customer
interface circuit, RINTFC. The transfer function of this resistive
divider is given by:
⎛
⎞
⎟
⎝ RF + RINTFC ⎠
∆VATT = VIOUT ⎜
⎜
RINTFC
.
Even if RF and RINTFC are designed to match, the two individual
resistance values will most likely drift by different amounts over
temperature. Therefore, signal attenuation will vary as a function
of temperature. Note that, in many cases, the input impedance,
RINTFC , of a typical analog-to-digital converter (ADC) can be as
low as 10 kΩ.
The ACS715 contains an internal resistor, a FILTER pin connection to the printed circuit board, and an internal buffer amplifier. With this circuit architecture, users can implement a simple
RC filter via the addition of a capacitor, CF (see Application 6)
from the FILTER pin to ground. The buffer amplifier inside of
the ACS715 (located after the internal resistor and FILTER pin
connection) eliminates the attenuation caused by the resistive
divider effect described in the equation for ∆VATT. Therefore, the
ACS715 device is ideal for use in high-accuracy applications that
cannot afford the signal attenuation associated with the use of an
external RC low-pass filter.
+5 V
Pin 3 Pin 4
IP–
IP–
VCC
Pin 8
Allegro ACS706
Application 5. When a low pass filter is constructed externally to a standard Hall effect device,
a resistive divider may exist between the filter
resistor, RF, and the resistance of the customer interface circuit, RINTFC. This resistive divider
will cause excessive attenuation, as given by the
transfer function for ∆VATT.
Voltage
Regulator
To all subcircuits
Filter
Dynamic Offset
Cancellation
0.1 MF
Resistive Divider
VIOUT
Pin 7
Amp
Out
N.C.
Pin 6
Input
RF
Application
Interface
Circuit
Low Pass Filter
Temperature
Coefficient
Gain
Offset
CF
RINTFC
Trim Control
GND
Pin 5
IP+
IP+
Pin 1 Pin 2
+5 V
VCC
Pin 8
Allegro ACS715
Hall Current
Drive
IP+
Pin 1
IP+
Pin 2
IP–
Pin 3
IP–
Pin 4
Sense Temperature
Coefficient Trim
Buffer Amplifier
and Resistor
Dynamic Offset
Cancellation
Application 6. Using the FILTER pin
provided on the ACS715 eliminates
the attenuation effects of the resistor divider between RF and RINTFC,
shown in Application 5.
Signal
Recovery
VIOUT
Pin 7
Input
Application
Interface
Circuit
Sense
Trim
0 Ampere
Offset Adjust
RINTFC
GND
Pin 5
FILTER
Pin 6
CF
12
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor
with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor
ACS715
Package LC, 8-pin SOIC
4.90
4º
8
0.21
3.90
6.00
A
1
0.84
2
0.25
8X
0.10 C
SEATING
PLANE
0.41
1.75 MAX
1.27
Two alternative patterns are used
ACS715T
RLCPPP
YYWWA
ACS
715
T
R
LC
PPP
YY
WW
A
1
2
Text 1
Text 2
Text 3
Package Branding
SEATING PLANE
GAUGE PLANE
C
0.18
All dimensions nominal, not for tooling use
(reference JEDEC MS-012 AA)
Dimensions in millimeters
A Terminal #1 mark area
8
7
3
6
4
5
Allegro Current Sensor
Device family number
Indicator of 100% matte tin leadframe plating
Operating ambient temperature range code
Package type designator
Primary sensed current
Date code: Calendar year (last two digits)
Date code: Calendar week
Date code: Shift code
ACS715T
RLCPPP
L...L
YYWW
ACS
715
T
R
LC
PPP
L...L
YY
WW
Allegro Current Sensor
Device family number
Indicator of 100% matte tin leadframe plating
Operating ambient temperature range code
Package type designator
Primary sensed current
Lot code
Date code: Calendar year (last two digits)
Date code: Calendar week
Copyright ©2006, 2007, Allegro MicroSystems, Inc.
The products described herein are manufactured under one or more of the following U.S. patents: 5,045,920; 5,264,783; 5,442,283; 5,389,889;
5,581,179; 5,517,112; 5,619,137; 5,621,319; 5,650,719; 5,686,894; 5,694,038; 5,729,130; 5,917,320; and other patents pending.
Allegro MicroSystems, Inc. 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 life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the
failure of that life support device or system, or to affect the safety or effectiveness of that device or system.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. 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, go to our website at:
www.allegromicro.com
13
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com