Allegro ACS714 current sensor datasheet
Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor
with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor
ACS714
13
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
Chopper Stabilization is an innovative circuit technique that is
used to minimize the offset voltage of a Hall element and an asso-
ciated on-chip amplifier. Allegro patented a Chopper Stabiliza-
tion 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 tempera-
ture 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.
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.
Chopper Stabilization Technique
Amp
Regulator
Clock/Logic
Hall Element
Sample and
Hold
Low-Pass
Filter
Concept of Chopper Stabilization Technique
+
–
IP+
IP+
IP–
IP–
I
P
7
5
5
8
+5 V
U1
LMV7235
VIOUT
V
OUT
GND
6
2
4
4
1
1
2
3
3
FILTER
VCC
ACS714
D1
1N914
R2
100 kΩ
R1
33 kΩ
R
PU
100 kΩ
Fault
C
BYP
0.1 μF
C
F
1 nF
+
–
IP+
IP+
IP–
IP–
7
5
8
+5 V
U1
LT1178
Q1
2N7002
VIOUT
V
OUT
V
PEAK
V
RESET
GND
6
2
4
1
3
D1
1N914
VCC
ACS714
R4
10 kΩ
R1
1 MΩ
R2
33 kΩ
R
F
10 kΩ
R3
330 kΩ
C
BYP
0.1 μF
C1
0.1 μF
C
OUT
0.1 μF
C
F
1 nF
C2
0.1 μF
FILTER
I
P
IP+
IP+
IP–
IP–
I
P
7
5
8
+5 V
D1
1N4448W
VIOUT
V
OUT
GND
6
2
4
1
3
FILTER
VCC
ACS714
R1
10 kΩ
C
BYP
0.1 μF
R
F
2 kΩ
C
F
1 nF
C1
A-to-D
Converter
Typical Applications
Application 5. 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.
Application 2. Peak Detecting Circuit
Application 4. Rectified Output. 3.3 V scaling and rectification application
for A-to-D converters. Replaces current transformer solutions with simpler
ACS circuit. C1 is a function of the load resistance and filtering desired.
R1 can be omitted if the full range is desired.
+
–
IP+
IP+
IP–
IP–
I
P
7
5
5
8
+5 V
LM321
VIOUT
V
OUT
GND
6
2
4
1
1
4
2
3
3
FILTER
VCC
ACS714
R2
100 kΩ
R1
100 kΩ
R3
3.3 kΩ
C
BYP
0.1 μF
C
F
0.01 μF
C1
1000 pF
R
F
1 kΩ
Application 3. This configuration increases gain to 610 mV/A
(tested using the ACS714ELC-05A).