ALLEGRO ACS712 ELCTR-05 Datasheet

ACS712

Fully Integrated, Hall Effect-Based Linear Current Sensor IC

with 2.1 kVRMS Isolation and a Low-Resistance Current Conductor

Features and Benefits

▪ Low-noise analog signal path
▪ Device bandwidth is set via the new FILTER pin
▪ 5 µs output rise time in response to step input current
▪ 80 kHz bandwidth
▪ Total output error 1.5% at T

= 25°C

A

▪ 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
▪ 66 to 185 mV/A output sensitivity
▪ Output voltage proportional to AC or DC currents
▪ Factory-trimmed for accuracy
▪ Extremely stable output offset voltage
▪ Nearly zero magnetic hysteresis
▪ Ratiometric output from supply voltage

TÜV America
Certificate Number:
U8V 06 05 54214 010

Package: 8 Lead SOIC (suffix LC)

Description

The Allegro™ ACS712 provides economical and precise
solutions for AC or DC 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, switch­mode power supplies, and overcurrent fault protection. The
device is not intended for automotive applications.

The device consists of a precise, low-offset, linear Hall 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 the Hall IC converts 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 (>V
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 sampling. The internal resistance of

this conductive path is 1.2 mΩ typical, providing low power

loss. The thickness of the copper conductor allows survival of

IOUT(Q)

)

Approximate Scale 1:1

Continued on the next page…

Typical Application

1

IP+

2

IP+

I

Application 1. The ACS712 outputs an analog signal, V
that varies linearly with the uni- or bi-directional AC or DC
primary sampled current, IP , within the range specified. CF
is recommended for noise management, with values that
depend on the application.

ACS712

P

3

FILTER

IP–

4

IP–

VCC

VIOUT

GND

8

7

6

5

V

C
1 nF

OUT

+5 V

C

BYP

0.1 µF

F

OUT

.

ACS712-DS, Rev. 15

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ACS712

Fully Integrated, Hall Effect-Based Linear Current Sensor IC

with

2.1 kVRMS Isolation and a Low-Resistance Current Conductor

Description (continued)

the device at up to 5× overcurrent conditions. The terminals of the

conductive path are electrically isolated from the signal leads (pins

5 through 8). This allows the ACS712 to be used in applications

requiring electrical isolation without the use of opto-isolators or
other costly isolation techniques.

The ACS712 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 Packing*

ACS712ELCTR-05B-T Tape and reel, 3000 pieces/reel –40 to 85 ±5 185

ACS712ELCTR-20A-T Tape and reel, 3000 pieces/reel –40 to 85 ±20 100

ACS712ELCTR-30A-T Tape and reel, 3000 pieces/reel –40 to 85 ±30 66

*Contact Allegro for additional packing options.

TA

(°C)

Optimized Range, IP

(A)

Sensitivity, Sens

(Typ) (mV/A)

Absolute Maximum Ratings

Characteristic Symbol Notes Rating Units

Supply Voltage V

Reverse Supply Voltage V

Output Voltage V

Reverse Output Voltage V

Output Current Source I

Output Current Sink I

Overcurrent Transient Tolerance I

Nominal Operating Ambient Temperature T

Maximum Junction Temperature T

Storage Temperature T

IOUT(Source)

IOUT(Sink)

J

CC

RCC

IOUT

RIOUT

P

A

(max) 165 ºC

stg

1 pulse, 100 ms 100 A

Range E –40 to 85 ºC

8 V

–0.1 V

8 V

–0.1 V

3 mA

10 mA

–65 to 170 ºC

Isolation Characteristics

Characteristic Symbol Notes Rating Unit

Dielectric Strength Test Voltage* V

Working Voltage for Basic Isolation V

Working Voltage for Reinforced Isolation V

* Allegro does not conduct 60-second testing. It is done only during the UL certification process.

Parameter Specification

Fire and Electric Shock

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ISO

WFSI

WFRI

Agency type-tested for 60 seconds per
UL standard 60950-1, 1st Edition

For basic (single) isolation per UL standard
60950-1, 1st Edition

For reinforced (double) isolation per UL standard
60950-1, 1st Edition

CAN/CSA-C22.2 No. 60950-1-03

UL 60950-1:2003

EN 60950-1:2001

2100 VAC

354 VDC or V

184 VDC or V

Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

pk

pk

2

ACS712

+5 V

VCC

(Pin 8)

Hall Current

Drive

Fully Integrated, Hall Effect-Based Linear Current Sensor IC

with

2.1 kVRMS Isolation and a Low-Resistance Current Conductor

Functional Block Diagram

IP+

(Pin 1)

IP+

(Pin 2)

IP−

(Pin 3)

IP−

(Pin 4)

Terminal List Table

Number Name Description

1 and 2 IP+ Terminals for current being sampled; fused internally

3 and 4 IP– Terminals for current being sampled; fused internally

5 GND Signal ground terminal

6 FILTER Terminal for external capacitor that sets bandwidth

7 VIOUT Analog output signal

8 VCC Device power supply terminal

Sense Temperature

Coefficient Trim

Cancellation

Dynamic Offset

Sense

Trim

GND

(Pin 5)

Signal

Recovery

0 Ampere

Offset Adjust

Pin-out Diagram

1

IP+

2

IP+

3

IP–

4

IP–

8

7

6

5

VCC

VIOUT

FILTER

GND

R

F(INT)

FILTER

(Pin 6)

VIOUT
(Pin 7)

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Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

3

ACS712

Fully Integrated, Hall Effect-Based Linear Current Sensor IC

with

2.1 kVRMS Isolation and a Low-Resistance Current Conductor

COMMON OPERATING CHARACTERISTICS

1

over full range of TA , CF = 1 nF, and VCC = 5 V, unless otherwise specified

Characteristic Symbol Test Conditions Min. Typ. Max. Units

ELECTRICAL CHARACTERISTICS

Supply Voltage V
Supply Current I
Output Capacitance Load C
Output Resistive Load R
Primary Conductor Resistance R
Rise Time t
Frequency Bandwidth f –3 dB, T
Nonlinearity E
Symmetry E

Zero Current Output Voltage V

Power-On Time t

Magnetic Coupling
Internal Filter Resistance

1

Device may be operated at higher primary current levels, IP, and ambient, TA , and internal leadframe temperatures, TA , provided that the Maximum

2

3

CC

CC

LOAD

LOAD

PRIMARYTA

r

LIN

SYM

IOUT(Q)

PO

R

F(INT)

VCC = 5.0 V, output open – 10 13 mA
VIOUT to GND – – 10 nF
VIOUT to GND 4.7 – – kΩ

= 25°C – 1.2 – mΩ

IP = IP(max), TA = 25°C, C

= 25°C; IP is 10 A peak-to-peak – 80 – kHz

A

Over full range of I
Over full range of I

P

P

= open – 3.5 – μs

OUT

Bidirectional; IP = 0 A, TA = 25°C –

Output reaches 90% of steady-state level, TJ = 25°C, 20 A present
on leadframe

4.5 5.0 5.5 V

– 1.5 – %

98 100 102 %

×

V

CC

0.5

– V

– 35 – µs

– 12 – G/A

1.7 kΩ

Junction Temperature, TJ(max), is not exceeded.

2

1G = 0.1 mT.

3

R

F(INT)

forms an RC circuit via the FILTER pin.

COMMON THERMAL CHARACTERISTICS

1

Min. Typ. Max. Units

Operating Internal Leadframe Temperature T

E range –40 – 85 °C

A

Value Units

Junction-to-Lead Thermal Resistance

Junction-to-Ambient Thermal Resistance R

1

Additional thermal information is available on the Allegro website.

2

The Allegro 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 connect-

2

R

Mounted on the Allegro ASEK 712 evaluation board 5 °C/W

θJL

Mounted on the Allegro 85-0322 evaluation board, includes the power con-

θJA

sumed by the board

23 °C/W

ing 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.

Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

4

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ACS712

Fully Integrated, Hall Effect-Based Linear Current Sensor IC

with

2.1 kVRMS Isolation and a Low-Resistance Current Conductor

x05B PERFORMANCE CHARACTERISTICS1 T

= –40°C to 85°C, CF = 1 nF, and VCC = 5 V, unless otherwise specified

A

Characteristic Symbol Test Conditions Min. Typ. Max. Units

Optimized Accuracy Range I
Sensitivity Sens Over full range of I

Noise V

Zero Current Output Slope ∆V

Sensitivity Slope ∆Sens

Total Output Error

1

Device may be operated at higher primary current levels, IP, and ambient temperatures, TA, provided that the Maximum Junction Temperature, T

2

P

NOISE(PP)

OUT(Q)

E

TOTIP

= 25°C 180 185 190 mV/A

P, TA

Peak-to-peak, TA = 25°C, 185 mV/A programmed Sensitivity,

= 47 nF, C

C

F

= open, 2 kHz bandwidth

OUT

TA = –40°C to 25°C – –0.26 – mV/°C
T

= 25°C to 150°C – –0.08 – mV/°C

A

T

= –40°C to 25°C – 0.054 – mV/A/°C

A

T

= 25°C to 150°C – –0.008 – mV/A/°C

A

=±5 A, TA = 25°C – ±1.5 – %

–5 – 5 A

– 21 – mV

is not exceeded.

2

Percentage of IP, with IP = 5 A. Output filtered.

x20A PERFORMANCE CHARACTERISTICS1 T

= –40°C to 85°C, CF = 1 nF, and VCC = 5 V, unless otherwise specified

A

Characteristic Symbol Test Conditions Min. Typ. Max. Units

Optimized Accuracy Range I
Sensitivity Sens Over full range of I

Noise V

Zero Current Output Slope ∆V

Sensitivity Slope ∆Sens

Total Output Error

1

Device may be operated at higher primary current levels, IP, and ambient temperatures, TA, provided that the Maximum Junction Temperature,

2

P

NOISE(PP)

OUT(Q)

E

TOTIP

= 25°C 96 100 104 mV/A

P, TA

Peak-to-peak, TA = 25°C, 100 mV/A programmed Sensitivity,
CF = 47 nF, C

= open, 2 kHz bandwidth

OUT

TA = –40°C to 25°C – –0.34 – mV/°C
T

= 25°C to 150°C – –0.07 – mV/°C

A

T

= –40°C to 25°C – 0.017 – mV/A/°C

A

T

= 25°C to 150°C – –0.004 – mV/A/°C

A

=±20 A, TA = 25°C – ±1.5 – %

–20 – 20 A

– 11 – mV

TJ(max), is not exceeded.

2

Percentage of IP, with IP = 20 A. Output filtered.

J(max)

,

x30A PERFORMANCE CHARACTERISTICS1 T

Characteristic Symbol Test Conditions Min. Typ. Max. Units

Optimized Accuracy Range I
Sensitivity Sens Over full range of I

Noise V

Zero Current Output Slope ∆V

Sensitivity Slope ∆Sens

Total Output Error

1

Device may be operated at higher primary current levels, IP, and ambient temperatures, TA, provided that the Maximum Junction Temperature,

TJ(max), is not exceeded.

2

Percentage of IP, with IP = 30 A. Output filtered.

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= –40°C to 85°C, CF = 1 nF, and VCC = 5 V, unless otherwise specified

A

P

NOISE(PP)

, TA = 25°C 63 66 69 mV/A

P

Peak-to-peak, TA = 25°C, 66 mV/A programmed Sensitivity,
CF = 47 nF, C

= open, 2 kHz bandwidth

OUT

–30 – 30 A

– 7 – mV

TA = –40°C to 25°C – –0.35 – mV/°C

OUT(Q)

2

E

TOTIP

T

= 25°C to 150°C – –0.08 – mV/°C

A

T

= –40°C to 25°C – 0.007 – mV/A/°C

A

T

= 25°C to 150°C – –0.002 – mV/A/°C

A

= ±30 A , TA = 25°C – ±1.5 – %

Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

5

ACS712

Mean Supply Current versus Ambient Temperature

10.30

10.25

10.20

10.15

10.10

10.05

(mA)

CC

10.00

9.95

Mean I

9.90

9.85

9.80

9.75

–0.5

–1.0

–1.5

–2.0

(mA)

–2.5

OM

I

–3.0

–3.5

–4.0

–4.5

–5.0

Mean Total Output Error versus Ambient Temperature

(%)

TOT

E

(V)

IOUT

V

0 A Output Voltage versus Ambient Temperature 0 A Output Voltage Current versus Ambient Temperature

2520

2515

2510

(mV)

2505

IOUT(Q)

2500

V

2495

2490

2485

Fully Integrated, Hall Effect-Based Linear Current Sensor IC

with

2.1 kVRMS Isolation and a Low-Resistance Current Conductor

Characteristic Performance

IP = 5 A, unless otherwise specified

V

= 5 V

CC

-50 -25 0 25 50 75 125100 150

Magnetic Offset versus Ambient Temperature

0

V
After excursion to 20 A

-50 -25 0 25 50 75 125100 150

8

6

4

2

0

–2

–4

–6

–8

–50 0–25 25 50

Output Voltage versus Sensed Current

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

–7 –6 –5 –4 –3 –2

-50 -25 0 25 50 75 125100 150

TA (°C)

= 5 V; IP = 0 A,

CC

T

(°C) TA (°C)

A

TA (°C)

V

= 5 V

CC

–1 0 1 2 3 4 5 6 7

IP (A)

IP = 0 A

TA (°C)

TA (°C)

–40

150

12575 100 150

25
85

Supply Current versus Supply Voltage

10.9

10.8

10.7

10.6

(mA)

10.5

CC

I

10.4

10.3

10.2

10.1

10.0

4.5 4.6 4.84.7 4.9

Nonlinearity versus Ambient Temperature

0.6

0.5

0.4

(%)

LIN

0.3

E

0.2

0.1

0

–50 0–25 25 50

V

5.0 5.35.1 5.2 5.4 5.5

VCC (V)

= 5 V

CC

Sensitivity versus Ambient Temperature

186.5

186.0

185.5

185.0

184.5

184.0

Sens (mV/A)

183.5

183.0

182.5

182.0

181.5

181.0
–50 0–25 25 50

Sensitivity versus Sensed Current

200.00

190.00

180.00

170.00

160.00

150.00

Sens (mV/A)

140.00

130.00

120.00

110.00

100.00

-6 -4 -2 0 2 4 6

0.20

0.15

0.10

0.05

(A)

0

OUT(Q)

I

–0.05

–0.10

–0.15

-50 -25 0 25 50 75 125100 150

TA (°C)

TA (°C)

Ip (A)

TA (°C)

–40

150

25
85

IP = 0 A

12575 100 150

12575 100 150

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Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

6

ACS712

Fully Integrated, Hall Effect-Based Linear Current Sensor IC

with

2.1 kVRMS Isolation and a Low-Resistance Current Conductor

Characteristic Performance

IP = 20 A, unless otherwise specified

Mean Supply Current versus Ambient Temperature

9.7

9.6

9.5

(mA)

CC

9.4

9.3

Mean I

9.2

9.1

-50 -25 0 25 50 75 125100 150

V

CC

= 5 V

TA (°C)

Magnetic Offset versus Ambient Temperature

0

–0.5

–1.0

–1.5

–2.0

(mA)

–2.5

OM

I

–3.0

–3.5

–4.0

–4.5

–5.0

Mean Total Output Error versus Ambient Temperature

(%)

TOT

E

–2

–4

–6

–8

5.0

4.5

4.0

3.5

3.0

(V)

2.5

IOUT

2.0

V

1.5

1.0

0.5

0 A Output Voltage versus Ambient Temperature

2525

2520

2515

2510

(mV)

2505

IOUT(Q)

2500

V

2495

2490

2485

V

= 5 V; IP = 0 A,

CC

After excursion to 20 A

-50 -25 0 25 50 75 125100 150

8

6

4

2

0

–50 0–25 25 50

TA (°C)

12575 100 150

TA (°C)

Output Voltage versus Sensed Current

V

= 5 V

CC

TA (°C)

–40
–20

25
85

125

0

–25 –20 –15 –10 –5 0

-50 -25 0 25 50 75 125100 150

5 10 15 20 25

IP (A)

IP = 0 A

TA (°C)

Supply Current versus Supply Voltage

10.4

10.2

10.0

9.8

(mA)

CC

I

9.6

9.4

9.2

9.0

4.5 4.6 4.84.7 4.9

Nonlinearity versus Ambient Temperature

0.35

0.30

0.25

(%)

0.20

LIN

E

0.15

0.10

0.05

0
–50 0–25 25 50

Sensitivity versus Ambient Temperature

100.8

100.6

100.4

100.2

100.0

99.8

Sens (mV/A)

99.6

99.4

99.2

99.0
–50 0–25 25 50

Sensitivity versus Sensed Current

110.00

108.00

106.00

104.00

102.00

100.00

98.00

Sens (mV/A)

96.00

94.00

92.00

90.00
–25 –20 –15 –10 –5 0

5.0 5.35.1 5.2 5.4 5.5

VCC (V)

TA (°C)

–40

150

25
85

12575 100 150

12575 100 150

T

(°C)

A

TA (°C)

5 10 15 20 25

Ip (A)

0 A Output Voltage Current versus Ambient Temperature

0.25

0.20

0.15

0.10

(A)

0.05

OUT(Q)

I

0

–0.05

–0.10

–0.15

-50 -25 0 25 50 75 125100 150

IP = 0 A

TA (°C)

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Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

7

ACS712

Mean Supply Current versus Ambient Temperature

(mA)

CC

Mean I

(mA)

OM

I

Mean Total Output Error versus Ambient Temperature

(%)

TOT

E

(V)

IOUT

V

0 A Output Voltage versus Ambient Temperature 0 A Output Voltage Current versus Ambient Temperature

2535

2530

2525

2520

2515

(mV)

2510

IOUT(Q)

2505

V

2500

2495

2490

2485

Fully Integrated, Hall Effect-Based Linear Current Sensor IC

with

2.1 kVRMS Isolation and a Low-Resistance Current Conductor

Characteristic Performance

IP = 30 A, unless otherwise specified

9.6

9.5

9.4

V

9.3

9.2

9.1

9.0

8.9

-50 -25 0 25 50 75 125100 150

Magnetic Offset versus Ambient Temperature

0

–0.5

–1.0

–1.5

–2.0

–2.5

–3.0

–3.5

–4.0

–4.5

–5.0

–2

–4

–6

–8

V

CC

After excursion to 20 A

-50 -25 0 25 50 75 125100 150

8

6

4

2

0

–50 0–25 25 50

Output Voltage versus Sensed Current

5.0

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

–30 –20 –10 0 10 20

-50 -25 0 25 50 75 125100 150

= 5 V

CC

TA (°C)

= 5 V; IP = 0 A,

TA (°C)

V

= 5 V

CC

TA (°C)

TA (°C)

IP (A)

IP = 0 A

12575 100 150

TA (°C)

–40
–20

125

25
85

30

Supply Current versus Supply Voltage

10.2

10.0

9.8

(mA)

9.6

CC

I

9.4

9.2

9.0

4.5 4.6 4.84.7 4.9

Nonlinearity versus Ambient Temperature

0.45

0.40

0.35

0.30

(%)

0.25

LIN

E

0.20

0.15

0.10

0.05

0

–50 0–25 25 50

Sensitivity versus Ambient Temperature

66.6

66.5

66.4

66.3

66.2

Sens (mV/A)

66.1

66.0

65.9

65.8

65.7
–50 0–25 25 50

Sensitivity versus Sensed Current

70.00

69.00

68.00

67.00

66.00

65.00

Sens (mV/A)

64.00

63.00

62.00

61.00

60.00
–30 –20 –10 0 10 20

0.35

0.30

0.25

0.20

0.15

(A)

0.10

OUT(Q)

0.05

I

0

–0.05

–0.10

–0.15

-50 -25 0 25 50 75 125100 150

5.0 5.35.1 5.2 5.4 5.5

VCC (V)

V

= 5 V

CC

T

(°C)

A

TA (°C)

Ip (A)

IP = 0 A

TA (°C)

12575 100 150

12575 100 150

TA (°C)

–40

150

25
85

30

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Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

8

Fully Integrated, Hall Effect-Based Linear Current Sensor IC

[{

[{

V

V





/

CC

/

5 V

‰



ACS712

Definitions of Accuracy Characteristics

with

2.1 kVRMS Isolation and a Low-Resistance Current Conductor

Sensitivity (Sens). The change in device 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 (V

). The product of the linear IC amplifier gain

NOISE

(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 (E

). The degree to which the voltage output from

LIN

the IC 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

where V

∆ gain × % sat (

1–

IOUT_full-scale amperes

2 (V

IOUT_half-scale amperes

V

IOUT_full-scale amperes

– V

– V

IOUT(Q)

= the output voltage (V) when the

IOUT(Q)

)

)

sampled current approximates full-scale ±IP .

Accuracy is divided into four areas:

• 0 A at 25°C. Accuracy at the zero current flow at 25°C, with-
out 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 the full-scale current

at 25°C, without the effects of temperature.

• Full-scale current over Δ temperature. Accuracy at the full-

scale current flow including temperature effects.

Ratiometry. The ratiometric feature means that its 0 A output,

V

proportional to its supply voltage, V

, (nominally equal to VCC/2) and sensitivity, Sens, are

IOUT(Q)

. The following formula is

CC

used to derive the ratiometric change in 0 A output voltage,

ΔV

IOUT(Q)RAT

The ratiometric change in sensitivity, ΔSens

(%).

100

V

IOUT(Q)VCC

100

Sens

VCC /

VCC

V

/ V

IOUT(Q)5V

5 V

Sens

(%), is defined as:

RAT

5V

Symmetry (E

). The degree to which the absolute voltage

SYM

output from the IC varies in proportion to either a positive or
negative full-scale primary current. The following formula is
used to derive symmetry:

IOUT_+ full-scale amperes

100

V

IOUT(Q)

– V

IOUT_–full-scale amperes

Quiescent output voltage (V

IOUT(Q)

–

IOUT(Q)

). The output of the device

when the primary current is zero. For a unipolar supply voltage,

it nominally remains at VCC ⁄ 2. Thus, VCC = 5 V translates into
V

= 2.5 V. Variation in V

IOUT(Q)

IOUT(Q)

can be attributed to the
resolution of the Allegro linear IC quiescent voltage trim and
thermal drift.

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 (E

). The accuracy represents the maximum devia-

TOT

tion of the actual output from its ideal value. This is also known
as the total output error. The accuracy is illustrated graphically in
the output voltage versus current chart at right.

Output Voltage versus Sampled Current

Accuracy at 0 A and at Full-Scale Current

Increasing V

Accuracy

v rO e ∆Temperature

Accuracy

Accuracy

v rO e ∆Temperature

25°C Only

Accuracy
25°C Only

0 A

Decreasing V

IP(min)

–I

(A)

P

Average

V

IOUT

(V)

IOUT

Accuracy
25°C Only

Full Scale

(V)

IOUT

IP(max)

Accuracy

v rO e ∆Temperature

+IP (A)

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Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

9

Fully Integrated, Hall Effect-Based Linear Current Sensor IC

ACS712

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, t

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, V
chart at right.

, is defined as the time it takes for the output

PO

with

2.1 kVRMS Isolation and a Low-Resistance Current Conductor

(min), as shown in the

CC

Rise time (tr). The time interval between a) when the device

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 device, in which ƒ(–3 dB) = 0.35 / tr.

Both tr and t

RESPONSE

are detrimentally affected by eddy current

losses observed in the conductive IC ground plane.

Power on Time versus External Filter Capacitance
200
180
160
140
120
100

(µs)

80

PO

t

60
40
20

0

0 10 20 30 40 50

Noise vs. Filter Cap

10000

1000

(mA)

100

(p-p)

10

Noise

1

0.01 0.1 1 10 100 1000

1200

1000

800

(µs)

600

r

t

400

200

0

0.1 1 10 100 1000

Noise versus External Filter Capacitance

Rise Time versus External Filter Capacitance

Expanded in chart at right

IP =

5 A

C

(nF)

F

C

(nF)

F

}

CF (nF)

IP =

0 A

Open 3.5
1 5.8

4.7 17.5
22 73.5
47 88.2

220 623
470 1120

CF (nF) tr (µs)

100 291.3

I (%)

90

10

0

Primary Current

Transducer Output

Rise Time, t

Step Response

TA=25°C

r

t

Output (mV)

15 A

Excitation Signal

Rise Time versus External Filter Capacitance

0

0.1 1 10 100
CF (nF)

(µs)
t

180
160
140
120
100

r

80
60
40
20

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Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

10

ACS712

Fully Integrated, Hall Effect-Based Linear Current Sensor IC

with

2.1 kVRMS Isolation and a Low-Resistance Current Conductor

Chopper Stabilization Technique

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 has 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

Regulator

Hall Element

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.

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.

Clock/Logic

Low-Pass
Filter

Amp

Hold

Sample and

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Concept of Chopper Stabilization Technique

Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

11

ACS712

T

+5 V

Fully Integrated, Hall Effect-Based Linear Current Sensor IC

with

2.1 kVRMS Isolation and a Low-Resistance Current Conductor

Typical Applications

+5 V

C

BYP

0.1 µF

C

VCC

VIOUT

FILTER

GND

8

7

6

5

1

IP+

2

IP+

I

ACS712

P

3

IP–

4

IP–

R

F

10 kΩ

OUT

0.1 µF

R1
1 MΩ

C

F

1 nF

R2
33 kΩ

Application 2. Peak Detecting Circuit

+5 V

C

BYP

0.1 µF

VCC

VIOUT

FILTER

GND

8

7

R

F

2 kΩ

6

5

1

IP+

2

IP+

ACS712

I

P

3

IP–

4

IP–

V

PEAK

C2

0.1 µF

R4
10 kΩ

V

OUT

+

–

U1

D1

LT11 78

1N914

R3
330 kΩ

C1

0.1 µF

V

Q1
2N7002

RESE

C

BYP

0.1 µF

1

IP+

2

VIOUT

IP+

I

ACS712

P

3

FILTER

IP–

4

IP–

VCC

GND

R1
100 kΩ

R2
100 kΩ

8

7

R

F

1 kΩ

6

C

F

0.01 µF

5

LM321

1

+

5

4

–

3

2

R3

3.3 kΩ

V

OUT

C1
1000 pF

Application 3. This configuration increases gain to 610 mV/A
(tested using the ACS712ELC-05A).

+5 V

C

V

OUT

C
1 nF

R1
10 kΩ

F

D1
1N4448W

C1

A-to-D
Converter

BYP

0.1 µF

1

VCC

IP+

2

VIOUT

IP+

I

ACS712

P

3

FILTER

IP–

4

IP–

GND

R1
33 kΩ

R

1

U1
LMV7235

PU

100 kΩ

Fault

R2
100 kΩ

8

V

7

OUT

6

C

F

1 nF

5

4

5

–

3

+

2

D1
1N914

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.

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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.

Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

12

Fully Integrated, Hall Effect-Based Linear Current Sensor IC

R





ACS712

Improving Sensing System Accuracy Using the FILTER Pin

with

2.1 kVRMS Isolation and a Low-Resistance Current Conductor

In low-frequency sensing applications, it is often advantageous

to add a simple RC filter to the output of the device. Such a low-

pass filter improves the signal-to-noise ratio, and therefore the
resolution, of the device output signal. However, the addition of

an RC filter to the output of a sensor IC can result in undesirable

device output attenuation — even for DC signals.

Signal attenuation, ∆V

, is a result of the resistive divider

ATT

effect between the resistance of the external filter, RF (see
Application 6), and the input impedance and resistance of the
customer interface circuit, R

. The transfer function of this

INTFC

resistive divider is given by:

Even if R

and R

F

∆V

V

=

AT T

IOUT

are designed to match, the two individual

INTFC





RF + R



INTFC

INTFC

.




resistance values will most likely drift by different amounts over

+5 V

Pin 3 Pin 4

IP– IP–

Application 6. 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, R
This resistive divider will cause excessive attenuation,

as given by the transfer function for ∆V

ATT

.

INTFC

.

0.1 µF

temperature. Therefore, signal attenuation will vary as a function

of temperature. Note that, in many cases, the input impedance,

, of a typical analog-to-digital converter (ADC) can be as

R

INTFC

low as 10 kΩ.

The ACS712 contains an internal resistor, a FILTER pin connec-

tion 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, C

(see Application 7)

F

from the FILTER pin to ground. The buffer amplifier inside of
the ACS712 (located after the internal resistor and FILTER pin

connection) eliminates the attenuation caused by the resistive

divider effect described in the equation for ∆V

. Therefore, the

ATT

ACS712 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.

VCC

Cancellation

Dynamic Offset

Gain

Voltage

Regulator

Amp

Pin 8

Temperature
Coefficient

To all subcircuits

Filter

Trim Control

Allegro ACS706

Out

Offset

VIOUT
Pin 7

R

F

N.C.
Pin 6

Low Pass Filter

C
1 nF

F

Resistive Divider

Input

Application

Interface

Circuit

R

INTFC

Application 7. Using the FILTER pin
provided on the ACS712 eliminates the
attenuation effects of the resistor divider
between R
cation 6.

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and R

F

, shown in Appli-

INTFC

+5 V

Pin 1

Pin 2

Pin 3

Pin 4

Recovery

GND
Pin 5

Signal

GND
Pin 5

0 Ampere

Offset Adjust

Allegro ACS712

Buffer Amplifier

and Resistor

FILTER

Pin 6

C

F

1 nF

Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

VIOUT
Pin 7

Input

Application

Interface

Circuit

R

INTFC

13

IP+ IP+

Pin 1 Pin 2

VCC

Pin 8

Hall Current

Drive

IP+

IP+

IP–

IP–

Sense Temperature

Coefficient Trim

Cancellation

Dynamic Offset

Sense

Trim

ACS712

Fully Integrated, Hall Effect-Based Linear Current Sensor IC

with

2.1 kVRMS Isolation and a Low-Resistance Current Conductor

Package LC, 8-pin SOIC

4.90 ±0.10

8

A

21

8X

C0.10

0.51

0.31

1.27 BSC

For Reference Only; not for tooling use (reference MS-012AA)
Dimensions in millimeters
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown

Terminal #1 mark area

A

Branding scale and appearance at supplier discretion

B

C

Reference land pattern layout (reference IPC7351
SOIC127P600X175-8M); all pads a minimum of 0.20 mm from all

D

adjacent pads; adjust as necessary to meet application process
requirements and PCB layout tolerances

3.90 ±0.10 6.00 ±0.20

Branded Face

SEATING

SEATING

PLANE

PLANE

1.75 MAX

0.25

0.10

8°
0°

0.25

0.17

1.04 REF

1.27

0.40

0.25 BSC

SEATING PLANE

C

C

GAUGE PLANE

8

0.65

1.75

21

PCB Layout Reference View

C

NNNNNNN
TPP-AAA
LLLLL

1

B

Standard Branding Reference View

N = Device part number
T = Device temperature range
P = Package Designator
A = Amperage
L = Lot number
Belly Brand = Country of Origin

1.27

5.60

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Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

14

ACS712

Fully Integrated, Hall Effect-Based Linear Current Sensor IC

with

2.1 kVRMS Isolation and a Low-Resistance Current Conductor

Revision History

Revision Revision Date Description of Revision

Rev. 15 November 16, 2012

Update rise time and isolation, I
patents

reference data,

OUT

Copyright ©2006-2013, Allegro MicroSystems, LLC
The products described herein are protected by U.S. patents: 5,621,319; 7,598,601; and 7,709,754.
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 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, 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.

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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

15