ACS726 Datasheet

ACS726
Galvanically Isolated Current Sensor IC
With Differential Output and Externally Adjustable Gain
FEATURES AND BENEFITS
• Fully differential architecture for improved immunity to
offset drift and common mode noise
• Spare differential back end amplifier for externally
adjustable gain and bandwidth using simple RC networks
• Greatly improved bandwidth through proprietary
amplifier and filter design techniques
• High bandwidth 120 kHz analog output
• Patented integrated digital temperature compensation
circuitry allows nearly closed-loop accuracy, through
entire temperature range, in an open loop sensor
• 1.1 mΩ primary conductor resistance for low power loss
and high inrush current withstanding capability
• Small footprint, low-profile QSOP24 package suitable
for space-constrained applications
• Integrated shield virtually eliminates capacitive coupling
from current conductor to die due to high dV/dt voltage
transients
Continued on the next page…
Package: 24-pin QSOP (suffix LF)
DESCRIPTION
The Allegro™ ACS726 current sensor IC family provides
economical and precise solutions for AC 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 fully differential output gives superior immunity to output
offset drift as well common mode noise.
ACS726 is the first current sensor IC to include a fully
differential back-end amplifier (BEA) that can be used to adjust
gain and bandwidth via external RC networks. The BEA is
fully independent and when unused, it can be powered down
to reduce power consumption.
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
Continued on the next page…
Approximate scale
1
2
3
4
5
6
IP+
IP+
IP+
IP+
IP+
IP+
NC
NC
VCC
VOUTGP
VOUTGN
ACS726
19
VINGN
18
VINGP
IP
7
8
9
10
11
12
IP–
IP–
IP–
IP–
IP–
IP–
VOUTP
VOUTN
GND
NC
NC
3.3 V
24
23
22
21
20
CBYPASS
0.1 µF
RFB1
RFB2
RIN1
RIN2
17
16
15
14
13
Typical Application
Current sensor IC gain can be set using RFB and RIN
ACS726-DS, Rev. 1
Galvanically Isolated Current Sensor IC
With Differential Output and Externally Adjustable Gain
ACS726
Features and Benefits (continued)
• 3 to 3.6 V, single supply operation
• Factory-trimmed sensitivity and quiescent output voltage for
improved accuracy
• Chopper stabilization results in extremely stable quiescent
output voltage
• Ratiometric output from supply voltage
Description (continued)
precise, proportional voltage is provided by the low-offset, chopperstabilized BiCMOS Hall IC, which is programmed for accuracy
after packaging. The output of the device has a positive differential
voltage ( VOUTP – VOUTN ) when an increasing current flows through
the primary copper conduction path (from pins 1 through 6, to pins
7 through 12), which is the path used for current sensing. The internal
resistance of this conductive path is 1.1 mΩ typical, providing low
power loss.
The terminals of the conductive path are electrically isolated from
the sensor IC signal leads (pins 13 through 24). This allows the
ACS726 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.
The ACS726 is provided in a small, low-profile surface mount
QSOP24 package (suffix LF). 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, excluding the BAE, is fully calibrated
prior to shipment from the factory.
Selection Guide
Part Number
Optimized Range for
Sensed Current, IP
(A)
Linear Range for
Sensed Current, IP
(A)
Sensitivity,
Sens (Typ)
(mV/A)1
ACS726LLFTR-20B-T3
±20
±20
100
ACS726LLFTR-40B-T3
±40
±40
50
1Measured differently when V
CC
Operating
Ambient Temperature Range
TA, (°C)
Packing2
–40 to 150
Tape and reel, 2500
pieces per 13-in. reel
= 3.3 V and using a 2000 mV dynamic range.
2Contact Allegro™ for additional packing options.
3
Variant not intended for automotive applications.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
ACS726
Galvanically Isolated Current Sensor IC
With Differential Output and Externally Adjustable Gain
Absolute Maximum Ratings
Characteristic
Supply Voltage
Reverse Supply Voltage
Symbol
Rating
Unit
VCC
VCC pin
Notes
6
V
VRCC
VCC pin
–0.1
V
VOUTP , VOUTN
VOUTP and VOUTN pins
6
V
VROUTP,
VROUTN
VOUTP and VOUTN pins
–0.1
V
VINGP, VINGIN
VINGP and VINGIN pins
6
V
BEA Reverse Input Voltage
VRINGP ,
VRINGN
VINGP and VINGN pins
–0.1
V
BEA Output Voltage
VOUTGP ,
VOUTGN
VOUTGP and VOUTGN pins
6
V
BEA Reverse Output Voltage
VROUTGP ,
VROUTGN
VOUTGP and VOUTGN pins
–0.1
V
VOUTP, VOUTN, VOUTGP, VOUTGN pins to GND
3
mA
VCC pin to VOUTP, VOUTN, VOUTGP, VOUTGN
10
mA
2100
VAC
277
VAC
391
Vpk or
VDC
Output Voltage
Reverse Output Voltage
BEA Input Voltage
Output Source Current
Output Sink Current
Electric Strength Test Voltage
Working Voltage
IOUT(SOURCE)
IOUT(SINK)
VESTV
Vworking
Between pins 1-12 and 13-24; 60 Hz, 1 minute (Agency Type Test),
TA = 25°C
For single protection according to UL 1577 standard; for higher
continuous voltage ratings, please contact Allegro
Operating Ambient Temperature
TA
–40 to 150
ºC
Maximum Junction Temperature
TJ(max)
165
ºC
Tstg
–65 to 170
ºC
Storage Temperature
Range L
Thermal Characteristics may require derating at maximum conditions, see application information
Characteristic
Package Thermal Resistance
(Junction to Ambient)
Symbol
RθJA
Test Conditions*
On Allegro ACS726 evaluation board (expected value)
Value
Unit
27
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
Galvanically Isolated Current Sensor IC
With Differential Output and Externally Adjustable Gain
ACS726
Pin-out Diagram and Terminal List Table
IP+ 1
24 NC
IP+ 2
23 NC
IP+ 3
22 VCC
IP+ 4
IP+ 5
IP+ 6
19 VINGN
IP– 7
18 VINGP
IP– 8
Terminal List Table
Number
Name
Function
21 VOUTGP
1 through 6
IP+
Terminals for current being sensed; fused internally
20 VOUTGN
7 through 12
IP–
Terminals for current being sensed; fused internally
15
GND
Signal ground terminal
17 VOUTP
16
VOUTN
Negative analog output
IP– 9
16 VOUTN
17
VOUTP
Positive analog output
IP– 10
15 GND
IP– 11
14 NC
18
VINGP
Gain stage positive analog input
IP– 12
13 NC
19
VINGN
Gain stage negative analog input
20
VOUTGN
Gain stage negative analog output
21
VOUTGP
Gain stage positive analog output
22
VCC
13,14,23,24
NC
Package LF, 24-Pin QSOP
Pin-out Diagram
Device power supply terminal
No Connection; connect to GND for optimal ESD performance
VCC
IP+
VOUTN VOUTP
Hall Current
Drive
Temperature
Sensor
EEPROM and
Control Logic
IP−
Dynamic Offset
Cancellation
Sensitivity
Control
IP+
VINGP VINGN
Offset
Control
VOUTGP
Signal
Recovery
VOUTGN
Back End Amplifier
(BEA) Stage
IP−
GND
Functional Block Diagram
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
ACS726
Galvanically Isolated Current Sensor IC
With Differential Output and Externally Adjustable Gain
COMMON OPERATING CHARACTERISTICS: not including BEA, TA= –40°C to 150°C, VCC = 3.3 V, CBYPASS = 0.1 μF;
unless otherwise specified
Characteristic
Supply Voltage
Supply Output Impedance
Supply Current
Output Capacitive Load
Output Resistive Load
Primary Conductor Resistance
Rise Time1
Propagation
Delay1
Response Time1
Internal Bandwidth1
Linearity
Error1
Saturation Voltage
Power-On Time1
Differential Quiescent Output Voltage
Symbol
Test Conditions
VCC
VCCIMP
Min.
Typ.
Max.
Unit
3
3.3
3.6
V
–
–
5
Ω
VCC = 3.3 V, no output load, BEA disabled
8
14
23
mA
ICCTOTAL
VCC = 3.0 V to 3.6 V, BEA Enabled
12
22
40
mA
CL
VOUTP to GND, VOUTN to GND
–
–
4.7
nF
RL
VOUTP to GND, VOUTN to GND
ICC
4.7
–
–
kΩ
TA = 25°C
–
1.1
–
mΩ
tr
IP = IP(MAX); TA = 25°C, CL = 1 nF
–
3.7
–
μs
tpd
IP = IP(MAX); TA = 25°C, CL = 1 nF
–
2.5
–
μs
IP = IP(MAX); TA = 25°C, CL = 1 nF, 90% input to
90% VIOUTdiff
–
5
–
μs
Small signal –3 dB; TA = 25°C, CL = 1 nF
–
120
–
kHz
Rprimary
tRESPONSE
BWi
-1
< 0.5
1
%
VSAT(H)
ErrLIN
TA = 25°C, RL = 4.7 kΩ to GND
VCC – 0.3
–
–
V
VSAT(L)
TA = 25°C, RL = 4.7 kΩ to VCC
–
–
0.3
V
TA = 25°C,
IP = IP(MAX)
–
85
–
µs
tPO
–
0
–
V
Common Mode Output Voltage1
VCMO
IP = 0, no load, VCC = 3.3 V, TA = 25°C to 150°C
1.4
1.65
1.9
V
Common Mode Offset Voltage
VCMOE
IP = 0, no load, VCC = 3.3 V, TA = 25°C to 150°C
-250
20
250
mV
Common Mode Output Voltage
Ratiometry1
∆VCMORAT
TA = 25C, VCC = 3.3 V +/-10%
–
100
–
%
Sensitivity Ratiometry1
∆SensRAT
TA = 25C, VCC = 3.3 V +/-10%
–
100
–
%
1See
VIOUTdiff(Q)
Across full range of IP
IP = 0
Characteristic Definitions section.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
ACS726
Galvanically Isolated Current Sensor IC
With Differential Output and Externally Adjustable Gain
ACS726-20B OPERATING CHARACTERISTICS: not including BEA, TA= –40°C to 150°C, VCC = 3.3 V, CBYPASS = 0.1 μF;
unless otherwise specified
Characteristic
Current Sensing Range
Differential Sensitivity1
Sensitivity Drift Over Lifetime2
Noise
Input-Referenced Noise Density
Zero Current Output Voltage
Differential Offset Voltage3
Symbol
Test Conditions
Min.
Typ.
Max.
Unit
–20
–
20
A
Across full range of IP , TA = 25°C
98
100
102
mV/A
Across full range of IP , TA = –40°C to 25°C, not
cold trimmed
–
100
–
mV/A
Across full range of IP , TA = 25°C to 150°C
97
100
103
mV/A
TA = -40C to 150C, shift after qualification testing
–
±1
–
%
–
10.5
–
mVRMS
–
305
–
µA / √Hz
IP = 0 A, TA = 25°C, VCC = 3.3 V
1.4
1.65
1.9
V
TA = 25°C
-15
±5
15
mV
–
±10
–
mV
IP
Sensdiff
∆SensLIFE
VNOISE(RMS) BWi = 120 kHz, TA = 25°C, CL= 1 nF to GND
IND(RMS)
VOUTP(Q) ,
VOUTN(Q)
VOE
BWi ≤ 120 kHz, TA = 25°C, CL= 1 nF to GND
TA = –40°C to 25°C, not cold trimmed
TA = 25°C to 150°C
Offset Voltage Drift Over Lifetime2
Total Output Error 4,5
Total Output Error Drift Over Lifetime2
∆VOELIFE
ErrTOT
∆ErrTOTLIFE
-15
±5
15
mV
TA = -40C to 150C, shift after qualification testing
–
±2
–
mV
IP = ±20 A, TA = 25°C, BWi = 120 kHz
-3
±1
3
%
IP = ±20 A, TA = –40°C to 25°C, BWi = 120 kHz,
not cold trimmed
–
±2
–
%
IP = ±20 A, TA = 25°C to 150°C, BWi = 120 kHz
-3
±1
3
%
TA = -40C to 150C, shift after qualification testing
–
±1
–
%
1This
parameter may drift a maximum of ∆SensLIFE over lifetime.
on characterization data obtained during standardized stress test for Qualification of Integrated Circuits. Cannot
be guaranteed. Drift is a function of customer application conditions. Please contact Allegro MicroSystems for further information.
3This parameter may drift a maximum of ∆V
OELIFE over lifetime.
4This parameter may drift a maximum of ∆Err
TOTLIFE over lifetime.
5Measured as a percentage of a 2000 mV dynamic range.
2Based
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
6
ACS726
Galvanically Isolated Current Sensor IC
With Differential Output and Externally Adjustable Gain
ACS726-40B OPERATING CHARACTERISTICS: not including BEA, TA= –40°C to 150°C, VCC = 3.3 V, CBYPASS = 0.1 μF;
unless otherwise specified
Characteristic
Current Sensing Range
Differential Sensitivity1
Symbol
Test Conditions
Min.
Typ.
Max.
Unit
–40
–
40
A
Across full range of IP , TA = 25°C
49
50
51
mV/A
Across full range of IP , TA = –40°C to 25°C, not
cold trimmed
–
50
–
mV/A
48.5
50
51.5
mV/A
–
±1
–
%
–
5.25
–
mVRMS
–
305
–
µA / √Hz
IP = 0 A, TA = 25°C, VCC = 3.3V
1.40
1.65
1.9
V
TA = 25°C
-15
±3
15
mV
–
±8
–
mV
-15
±3
15
mV
–
±2
–
mV
IP
Sensdiff
Across full range of IP , TA = 25°C to 150°C
Sensitivity Drift Over Lifetime2
Noise
Input-Referenced Noise Density
Zero Current Output Voltage
Differential Offset Voltage3
∆SensLIFE
TA = -40C to 150C, shift after qualification testing
VNOISE(RMS) BWi = 120 kHz, TA = 25°C, CL= 1 nF to GND
IND(RMS)
VOUTP(Q) ,
VOUTN(Q)
VOE
BWi ≤ 120 kHz, TA = 25°C, CL= 1 nF to GND
TA = –40°C to 25°C, not cold trimmed
TA = 25°C to 150°C
Offset Voltage Drift Over Lifetime2
∆VOELIFE
TA = -40C to 150C, shift after qualification testing
IP = ±40 A, TA = 25°C, BWi = 120 kHz
Total Output Error 4,5
Total Output Error Drift Over Lifetime2
ErrTOT
∆ErrTOTLIFE
-2.5
±1
2.5
%
IP = ±40 A, TA = –40°C to 25°C, BWi = 120 kHz,
not cold trimmed
–
±2
–
%
IP = ±40 A, TA = 25°C to 150°C, BWi = 120 kHz
-2.5
±1
2.5
%
–
±1
–
%
TA = -40C to 150C, shift after qualification testing
1This
parameter may drift a maximum of ∆SensLIFE over lifetime.
on characterization data obtained during standardized stress test for Qualification of Integrated Circuits. Cannot
be guaranteed. Drift is a function of customer application conditions. Please contact Allegro MicroSystems for further information.
3This parameter may drift a maximum of ∆VOELIFE over lifetime.
4This parameter may drift a maximum of ∆Err
TOTLIFE over lifetime.
5Measured as a percentage of a 2000 mV dynamic range.
2Based
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
7
ACS726
Galvanically Isolated Current Sensor IC
With Differential Output and Externally Adjustable Gain
Differential Back End Amplifier (BEA) OPERATING CHARACTERISTICS1: TA= –40°C to 150°C, VCC = 3.3 V, CBYPASS = 0.1
μF; unless otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Unit
Load
Output Capacitive Load
CL(BEA)
VOUTGP to GND, VOUTGN to GND
–
–
4.7
nF
Output Resistive Load
RL(BEA)
VOUTGP to GND, VOUTGN to GND
4.7
–
–
kΩ
Gain Setting Resistance
Feedback Resistor1
RFB(BEA)
9.4
–
50
kΩ
Resistor1
RIN(BEA)
4.7
–
25
kΩ
GOL(BEA)
–
90
–
dB
Input
AC Performance
Open Loop Gain
Closed Loop
Gain2
Bandwidth
Gain Bandwidth Product
Differential Slew Rate
Settling Time to 1%
Input-Referred Voltage Noise Density
GCL(BEA)
BW(BEA)
GBWP(BEA)
2
–
10
–
GCL(BEA) = 2, CL(BEA) = 1 nF
–
1000
–
kHz
CL(BEA) = 1 nF
–
2000
–
kHz
SRD(BEA)
GCL(BEA) = 2, CL(BEA) = 1 nF
–
1.5
–
V/µs
tS(BEA)
GCL(BEA) = 2, CL(BEA) = 1 nF,
VOUTGP – VOUTGN = 100 mV
–
3
–
µs
TA = 25°C, BW(BEA) < 120 kHz, GCL(BEA) = 2
–
40
–
nV/ √Hz
At TA = 25°C
-7
±3
7
mV
At TA = 25°C to 150°C
-7
±3
7
mV
GCL(BEA) = 2, CL(BEA) = 1 nF
3.5
7
17
mA
GCL(BEA) = 2, CL(BEA) = 1 nF, BW(BEA) < 1 kHz
–
-70
–
dB
VCMIRMIN
(BEA)
VCC = 3.3 V, GCL(BEA) = 2, RIN(BEA) = 4.7 K,
RFB(BEA) = 9.4 K
1
–
–
V
VCMIRMAX
VCC = 3.3 V, GCL(BEA) = 2, RIN(BEA) = 4.7 K,
RFB(BEA) = 9.4 K
–
–
2.15
V
GCL(BEA) = 2, CL(BEA) = 1 nF, BW(BEA) < 1 kHz
–
60
–
dB
-1.5
<1
1.5
µA
VCC –
0.3
–
–
V
VND(BEA)
DC Performance
Input-Referred Differential Offset
Voltage
VOEIR(BEA)
Quiescent Operating Current3
IQ(BEA)
Power Supply Rejection Ratio
PSRR(BEA)
Input
Minimum Common Mode Input Range
(BEA)
Common Mode Rejection Ratio
Input Bias Current
CMRR(BEA)
Ibias(BEA)
VCC = 3.3 V, VINGP = VINGN = 1.65 V
Output
Saturation Voltage
VSAT(H)(BEA)
TA = 25°C, RL(BEA) = 4.7 kΩ to GND
VSAT(L)(BEA)
TA = 25°C, RL(BEA) = 4.7 kΩ to VCC
–
–
0.3
V
Common Mode Output Voltage
VCMO(BEA)
VCC = 3.3 V, GCL = 2, TA = 25°C to 150°C
1.4
1.65
1.9
V
Common Mode Offset Voltage
VCMOE(BEA)
VCC = 3.3 V, GCL = 2, TA = 25°C to 150°C
-250
±20
250
mV
–
<1
–
Ω
–
<±0.1
–
%
DC Output Resistance
ROUT(BEA)
Linearity
ErrLin(BEA)
GCL(BEA) = 2, Over 2 V differential dynamic
range
1If
larger resistor values are used, settling time deteriorates. Adding a capacitor in parallel with the feedback resistor improves settling time.
does not guarantee BAE performance and stability for Closed Loop Gain outside the recommended range.
3The Back End Amplifier can be powered-down by connecting VINGP and VINGN to GND, causing VOUTGP and VOUTGN to be = Vcc/2
2Allegro
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
8
ACS726
Galvanically Isolated Current Sensor IC
With Differential Output and Externally Adjustable Gain
CHARACTERISTIC PERFORMANCE DATA
Data taken using the ACS726LLFTR-20B-T
Timing Data
Response Time (90%input-90%output)
IP=20 A, 10% to 90% IP rise time < 1 µS, CBYPASS = 0.1 µF, CL =1 nF from VOUTP to GND and VOUTN to GND
IP=20A
90% of input
VOUTP
VOUTN
tRESPONSE=4.3µS
90% of output
VOUTP-VOUTN
Rise Time (10%output-90%output)
IP=20 A, 10% to 90% IP rise time < 1 µS, CBYPASS = 0.1 µF, CL = 1 nF from VOUTP to GND and VOUTN to GND
IP=20A
VOUTP
VOUTN
tr=3.5µS
90% of output
VOUTP-VOUTN
10% of output
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
9
ACS726
Galvanically Isolated Current Sensor IC
With Differential Output and Externally Adjustable Gain
Propagation Delay(20%input-20%output)
IP = 20 A, 10% to 90% IP rise time < 1 µS, CBYPASS = 0.1 µF, CL = 1 nF from VOUTP to GND and VOUTN to GND
IP=20A
VOUTP
20% of input
VOUTN
tpd=2.5µS
VOUTP-VOUTN
20% of output
Power-On Time
IP = 20 A, 10% to 90% rise time < 1 µS
VOUTP
VOUTN
VCC
VCC(min)=3V
tPO=83µS
VOUTP-VOUTN
90% of output
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
10
Galvanically Isolated Current Sensor IC
With Differential Output and Externally Adjustable Gain
ACS726
CHARACTERISTICS DEFINITIONS
Accuracy Characteristics
Total Output Error (ETOT)* The maximum deviation of the
Differential Sensitivity (Sensdiff) The change in the differential
sensor IC output (VOUTP – VOUTN ) 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.
Noise (VNOISE(RMS)) The unfiltered output noise of the current
sensor IC. Dividing the noise (mV) by the sensitivity (mV/A)
provides the smallest current that the device is able to resolve.
Linearity Error (ErrLIN)* The ACS726 is designed to provide
a linear output in response to a ramping current. Consider two
current levels, I1 and I2. Ideally, the sensitivity of a device is the
same for both currents, for a given supply voltage and temperature. Nonlinearity is present when there is a difference between
the sensitivities measured at I1 and I2. Nonlinearity is calculated
separately for the positive (ErrLIN pos) and negative (ErrLINneg)
applied currents as follows:
{(
{(
)}
)}
actual output from its ideal value, also referred to as accuracy,
illustrated graphically in the Output voltage versus Sensed current chart .
ETOT is divided into four areas:
0 A at 25°C. Accuracy at the zero current flow at 25°C, without
the effects of temperature.
0 A over Δ temperature. Accuracy at the zero current flow
including temperature effects.
Full-scale current at 25°C. Accuracy at the full-scale current at
25°C, without the effects of temperature.
Full-scale current over Δ temperature. Accuracy at the fullscale
current flow including temperature effects.
ETOT(IP) = 100(%) X
[
]
(VIOUTdiff(Ip) - VIOUTdiff_IDEAL(Ip) )
Sensdiff_IDEAL X IP
Where
VIOUTdiff_IDEAL(IP) = VIOUTdiff_IDEAL(Q) + (Sensdiff_IDEAL X Ip)
where:
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.
SensIx = (VIOUTdiff(Ix) – VIOUTdiff(Q))/ Ix and IPOSx and INEGx
are positive and negative currents. Then:
This is illustrated in the total output error versus sensed current
chart.
ErrLIN = max( ErrLINpos, ErrLINneg )
Ratiometry The ratiometric feature means that the Common Mode
ErrLINpos = 100(%) X 1 -
SensIPOS2
SensIPOS1
ErrLINneg = 100(%) X 1 -
SensINEG2
SensINEG1
Differential Quiescent Output Voltage (VIOUTdiff(Q))* The differential output of the sensor IC when the primary current is zero.
It is nominally 0 V.
Differential Offset Voltage (VOE) The deviation of the device
output, from its ideal quiescent value of 0 V, due to nonmagnetic
causes. To convert this voltage to amperes, divide by the device
sensitivity, Sens.
Common Mode Output Voltage (VCMO ) The average of the
positive and negative zero current output voltages: (VOUTP(Q) +
VOUTN(Q) ) / 2. VCMO nominally equals VCC / 2.
Common Mode Offset Voltage (VCMOE) The deviation of the
Output Voltage, VCMO , and Differential Sensitivity, Sensdiff , are
proportional to the supply voltage, VCC . The following formula is
used to derive the ratiometric change in common mode 0 A output
voltage, ΔVCMORAT (%).
100

VCMO(VCC) / VCMO(3.3V)
VCC / 3.3 V

The ratiometric change in sensitivity, ΔSensRAT (%), is defined as:
100

Sensdiff(VCC) /Sensdiff(3.3V)
VCC / 3.3 V

Common Mode Output Voltage from its ideal value of VCC / 2.
*Definitions of VIOUT:
• VIOUTdiff = VOUTP – VOUTN
• VIOUTdiff(Q) = VOUTP(Q) – VOUTN(Q) ; sensed current equals 0 A
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115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
11
ACS726
Galvanically Isolated Current Sensor IC
With Differential Output and Externally Adjustable Gain
Output Voltage versus Sensed Current
Total Output Error at 0 A and at Full-Scale Current
ETOT Across
full temperature
Increasing VIOUTdiff (V)
ETOT at
25°C Only
Average
VIOUT
ETOT Across
full temperature
ETOT at
25°C Only
-20 A (20 AB)
-40 A (40 AB)
VIOUT(Q)
–IP (A)
+IP (A)
Full Scale
20 A (20 AB)
40 A (40 AB)
0A
ETOT at
25°C Only
Decreasing VIOUTdiff (V)
ETOT Across
full temperature
Total Output Error versus Sensed Current
+ETOT
Across Temperature
25°C Only
–IP
+IP
–ETOT
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
12
ACS726
Galvanically Isolated Current Sensor IC
With Differential Output and Externally Adjustable Gain
Dynamic Response Characteristics
Power-On Time
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. PowerOn Time, tPO , is defined as the time it takes for the output voltage to settle within ±10% of its steady state value when full scale
IP is applied, after the power supply has reached its minimum
specified operating voltage, VCC(min), as shown in the chart at
right.
V
VCC
VCC(typ.)
VIOUTdiff
90% VIOUT
VCC(min.)
Rise Time (tr ) The time interval between a) when the sensor
IC differential output reaches 10% of its full scale value, and b)
when it reaches 90% of its full scale value.
tPO
t1
t2
t1= time at which power supply reaches
minimum specified operating voltage
Propagation Delay (tpd ) The time interval between a) when the
input current reaches 20% of it’s final value, and b) when the differential output reaches 20% of its final value.
t2= time at which output voltage settles
within ±10% of its steady state value
under an applied magnetic field
Response Time (tRESPONSE) The time interval between a)
when the applied current reaches 90% of its final value, and b)
when the sensor differential output reaches 90% of its final value
corresponding to the applied current.
0
t
Rise Time and Propagation Delay
Response Time
(%)
90
(%)
90
Primary Current
VIOUTdiff
Primary Current
VIOUTdiff
Rise Time, t r
Response Time, t RESPONSE
0
t
20
10
0
t
Propagation Delay, t pd
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
13
Galvanically Isolated Current Sensor IC
With Differential Output and Externally Adjustable Gain
ACS726
PACKAGE OUTLINE DRAWING
For Reference Only – Not for Tooling Use
(Reference JEDEC MO-137 AE)
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
0.40
8.66 ±0.10
0.635
8º
0º
24
0.25
0.15
3.91 ±0.10
2.30
5.00
5.99 ±0.20
1.27
0.41
A
1.04 REF
1
2
0.25 BSC
Branded Face
24X
C
1.75 MAX
0.20 C
B
PCB Layout Reference View
SEATING PLANE
GAUGE PLANE
SEATING
PLANE
0.30
0.20
0.25 MAX
0.635 BSC
NNNNNNNNNNNNN
TLF-AAA
LLLLLLLLLLL
A
Terminal #1 mark area
B
Reference pad layout (reference IPC7351 SOP63P600X175-24M)
All pads a minimum of 0.20 mm from all adjacent pads; adjust as
necessary to meet application process requirements and PCB layout
tolerances
C
Branding scale and appearance at supplier discretion
C
PCB Layout Reference View
N = Device part number
T = Temperature code
LF = (Literal) Package type
A = Amperage
Package LF, 24-Pin QSOP
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
14
Galvanically Isolated Current Sensor IC
With Differential Output and Externally Adjustable Gain
ACS726
Document Revision History
Revision
Date
–
April 3, 2014
1
August 13. 2014
Change
Initial release
Removed “A” deisgnator from part number and reformatted document
Copyright ©2012-2014, 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.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
15
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