ACS712

ACS712_06 ALLEGRO | Alldatasheet

Document overview

• Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
• PDF pages: 12

Technical content

Approximate Scale 1:1 that varies linearly with the uni- or bi-directional AC or DC primary sensed current, I P , within the range specified. CF is recommended for noise management, with values that depend on the application. ACS712

Description

The Allegro ® ACS712 provides economical and precise solutions for AC or DC current sensing in industrial, automotive, 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 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 (>V IOUT(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 ACS712-DS, Rev.1 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 ▪ 50 kHz bandwidth ▪ Total output error 1.5% at T A = 25°C, and 4% at –40°C to 85°C ▪ Small footprint, low-profile SOIC8 package ▪ 1.2 m Ω internal conductor resistance ▪ 2.1 kV RMS 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 Fully Integrated, Hall Effect-Based Linear Current Sensor with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor Continued on the next page… Package: 8 pin SOIC (suffix LC) Typical Application IP+ IP+ IP– IP– IP 5GND ACS712 +5 V VIOUT VOUT 6FILTER VCC CBYP 0.1 μF CF 1 nF

Fully Integrated, Hall Effect-Based Linear Current Sensor with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current ConductorACS712 2Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com Selection Guide Part Number Packing* TOP (°C) Optimized Range, IP (A) Sensitivity, Sens (Typ) (mV/A) 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. loss. The thickness of the copper conductor allows survival 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 ACS712 current sensor 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. Description (continued) Absolute Maximum Ratings Characteristic Symbol Notes Rating Units Supply Voltage V CC 8V Reverse Supply Voltage V RCC –0.1 V Output Voltage V IOUT 8V Reverse Output Voltage V RIOUT –0.1 V Output Current Source I IOUT(Source) 3m A Output Current Sink I IOUT(Sink) 10 mA Overcurrent Transient Tolerance I P 100 total pulses, 250 ms duration each, applied at a rate of 1 pulse every 100 seconds. 60 A Maximum Transient Sensed Current I R(max) Junction Temperature, T J < TJ(max) 60 A Nominal Operating Ambient Temperature T A Range E –40 to 85 ºC Maximum Junction T J(max) 165 ºC Storage Temperature T stg –65 to 170 ºC TÜV America Certificate Number: U8V 06 05 54214 010 Parameter Specification Fire and Electric Shock CAN/CSA-C22.2 No. 60950-1-03 UL 60950-1:2003 EN 60950-1:2001

Fully Integrated, Hall Effect-Based Linear Current Sensor with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current ConductorACS712 3Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com VCC (Pin 8) (Pin 7) VIOUT RF(INT) GND (Pin 5) FILTER (Pin 6) Dynamic Offset Cancellation IP+ (Pin 1) IP+ (Pin 2) IP− (Pin 3) IP− (Pin 4) Sense Trim Signal Recovery Sense Temperature Coefficient Trim

0 Ampere

+5 V IP+ IP+ IP– IP– VCC VIOUT FILTER GND Terminal List Table Number Name Description 1 and 2 IP+ Terminals for current being sensed; fused internally 3 and 4 IP– Terminals for current being sensed; 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

Fully Integrated, Hall Effect-Based Linear Current Sensor with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current ConductorACS712 4Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com COMMON OPERATING CHARACTERISTICS1 over full range of TOP , CF = 1 nF, and VCC = 5 V, unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. Max. Units

ELECTRICAL CHARACTERISTICS

Supply Voltage V CC 4.5 5.0 5.5 V Supply Current I CC VCC = 5.0 V, output open 6 8 11 mA Output Zener Clamp Voltage V Z ICC = 11 mA, TA = 25°C 6 8.3 – V Output Resistance R IOUT IIOUT = 1.2 mA, TA=25°C – 1 2 Ω Output Capacitance Load C LOAD VIOUT to GND – – 10 nF Output Resistive Load R LOAD VIOUT to GND 4.7 – – k Ω Primary Conductor Resistance R PRIMARY TA = 25°C – 1.2 – m Ω RMS Isolation Voltage V ISORMS Pins 1-4 and 5-8; 60 Hz, 1 minute, TA=25°C 2100 – – V DC Isolation Voltage V ISODC Pins 1-4 and 5-8; 1 minute, TA=25°C – 5000 – V Propagation Time t PROP IP = IP(max), TA = 25°C, COUT = open – 3 – μs Response Time t RESPONSE IP = IP(max), TA = 25°C, COUT = open – 7 – μs Rise Time t r IP = IP(max), TA = 25°C, COUT = open – 5 – μs Frequency Bandwidth f –3 dB, T A = 25°C; IP is 10 A peak-to-peak 50 – – kHz Nonlinearity E LIN Over full range of IP – ±1 ±1.5 % Symmetry E SYM Over full range of IP 98 100 102 % Zero Current Output Voltage V IOUT(Q) Bidirectional; IP = 0 A, TA = 25°C – VCC × 0.5 –V Magnetic Offset Error VERROM IP = 0 A, after excursion of 5 A – 0 – mV Clamping Voltage VCH Typ. –110 VCC × 0.9375 Typ. +110 mV VCL Typ. –110 VCC × 0.0625 Typ. +110 mV Power-On Time t PO Output reaches 90% of steady-state level, TJ = 25°C, 20 A present on leadframe –3 5– μs Magnetic Coupling2 – 12 – G/A Internal Filter Resistance3 RF(INT) 1.7 k Ω 1Device may be operated at higher primary current levels, IP, and ambient, TA , and internal leadframe temperatures, TOP , provided that the Maximum Junction Temperature, TJ(max), is not exceeded. 21G = 0.1 mT. 3RF(INT) forms an RC circuit via the FILTER pin. COMMON THERMAL CHARACTERISTICS1 Min. Typ. Max. Units Operating Internal Leadframe Temperature T OP E range –40 – 85 °C Value Units Junction-to-Lead Thermal Resistance2 RθJL Mounted on the Allegro ASEK 712 evaluation board 5 °C/W Junction-to-Ambient Thermal Resistance R θJA Mounted on the Allegro 85-0322 evaluation board, includes the power con- sumed by the board 23 °C/W 1Additional thermal information is available on the Allegro website. 2The 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- 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 Informa- tion section of this datasheet.

Fully Integrated, Hall Effect-Based Linear Current Sensor with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current ConductorACS712 5Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com x05A PERFORMANCE CHARACTERISTICS TOP = –40°C to 85°C1, CF = 1 nF, and VCC = 5 V, unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. Max. Units Optimized Accuracy Range I P –5 – 5 A Sensitivity2 SensTA Over full range of IP, TA = 25°C – 185 – mV/A SensTOP Over full range of IP 178 – 193 mV/A Noise V NOISE(PP) Peak-to-peak, TA= 25°C, 185 mV/A programmed Sensitivity, CF = 4.7 nF, COUT = open, 20 kHz bandwidth –4 5–m V Peak-to-peak, TA = 25°C, 185 mV/A programmed Sensitivity, CF = 47 nF, COUT = open, 2 kHz bandwidth –2 0–m V Peak-to-peak, TA = 25°C, 185 mV/A programmed Sensitivity, CF = 1 nF, COUT = open, 50 kHz bandwidth –7 5–m V Electrical Offset Voltage V OE IP = 0 A –40 – 40 mV Total Output Error3 ETOT IP =±5 A, TA = 25°C – ±1.5 – % 1Device may be operated at higher primary current levels, IP, and ambient temperatures, TOP, provided that the Maximum Junction Temperature, TJ(max), is not exceeded. 2At –40°C Sensitivity may shift as much 9% outside of the datasheet limits. 3Percentage of IP, with IP = 5 A. Output filtered. x20A PERFORMANCE CHARACTERISTICS TOP = –40°C to 85°C1, CF = 1 nF, and VCC = 5 V, unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. Max. Units Optimized Accuracy Range I P –20 – 20 A Sensitivity2 SensTA Over full range of IP, TA = 25°C – 100 – mV/A SensTOP Over full range of IP 97 – 103 mV/A Noise V NOISE(PP) Peak-to-peak, TA= 25°C, 100 mV/A programmed Sensitivity, CF = 4.7 nF, COUT = open, 20 kHz bandwidth –2 4–m V Peak-to-peak, TA = 25°C, 100 mV/A programmed Sensitivity, CF = 47 nF, COUT = open, 2 kHz bandwidth –1 0–m V Peak-to-peak, TA = 25°C, 100 mV/A programmed Sensitivity, CF = 1 nF, COUT = open, 50 kHz bandwidth –4 0–m V Electrical Offset Voltage V OE IP = 0 A –30 – 30 mV Total Output Error3 ETOT IP =±20 A, TA = 25°C – ±1.5 – % 1Device may be operated at higher primary current levels, IP, and ambient temperatures, TOP, provided that the Maximum Junction Temperature, TJ(max), is not exceeded. 2At –40°C Sensitivity may shift as much 9% outside of the datasheet limits. 3Percentage of IP, with IP = 20 A. Output filtered. x30A PERFORMANCE CHARACTERISTICS TOP = –40°C to 85°C1, CF = 1 nF, and VCC = 5 V, unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. Max. Units Optimized Accuracy Range I P –30 – 30 A Sensitivity2 SensTA Over full range of IP , TA = 25°C – 66 – mV/A SensTOP Over full range of IP 64 – 68 mV/A Noise V NOISE(PP) Peak-to-peak, TA= 25°C, 66 mV/A programmed Sensitivity, CF = 4.7 nF, COUT = open, 20 kHz bandwidth –2 0–m V Peak-to-peak, TA = 25°C, 66 mV/A programmed Sensitivity, CF = 47 nF, COUT = open, 2 kHz bandwidth –7– m V Peak-to-peak, TA = 25°C, 66 mV/A programmed Sensitivity, CF = 1 nF, COUT = open, 50 kHz bandwidth –3 5–m V Electrical Offset Voltage V OE IP = 0 A –30 – 30 mV Total Output Error3 ETOT IP = ±30 A , TA = 25°C – ±1.5 – % 1Device may be operated at higher primary current levels, IP, and ambient temperatures, TOP, provided that the Maximum Junction Temperature, TJ(max), is not exceeded. 2At –40°C Sensitivity may shift as much 9% outside of the datasheet limits. 3Percentage of IP, with IP = 30 A. Output filtered.

Fully Integrated, Hall Effect-Based Linear Current Sensor with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current ConductorACS712 6Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com Characteristic Performance IP = 5 A, Sens = 185 mV/A unless otherwise specified 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 -50 0 50 100 150 200 TA (°C) TA (°C) Mean ICC (mA) VERROM (mV) VIOUT (V) 8.5 8.7 8.9 9.1 9.3 9.5 9.7 9.9 10.1 10.3 10.5 V CC (V) ICC (mA)ELIN (%) TA (°C) -50 0 50 100 150 200 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 -50 0 50 100 150 200 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 TA (°C) Mean ETOT (%) -15.0 -10.0 -5.0 0.0 5.0 10.0 15.0 -50 0 50 100 150 200 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 - 1 0 - 8 - 6 - 4 - 2 024681 0 Ip (A) Ip (A) 176.0 178.0 180.0 182.0 184.0 186.0 188.0 -10 -8 -6 -4 -2 0 2 4 6 8 10 Sens (mV/A)-40 150 TA (°C) -40 TA (°C) Mean Supply Current versus Ambient Temperature VCC = 5 V Supply Current versus Supply Voltage Magnetic Offset versus Ambient Temperature Nonlinearity versus Ambient Temperature IP = 10 A Mean Total Output Error versus Ambient Temperature IP = 10 A Output Voltage versus Sensed Current Sensitivity versus Sensed Current

Fully Integrated, Hall Effect-Based Linear Current Sensor with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current ConductorACS712 7Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com -50 0 50 100 150 200 TA (°C) TA (°C) Mean ICC (mA) VERROM (mV) VIOUT (V) 8.5 8.7 8.9 9.1 9.3 9.5 9.7 9.9 10.1 10.3 10.5 V CC (V) ICC (mA)ELIN (%) TA (°C) -50 0 50 100 150 200 0.20 0.40 0.60 0.80 1.00 -50 0 50 100 150 200 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 TA (°C) Mean ETOT (%) -5.0 -3.0 -2.0 -4.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 -50 0 50 100 150 200 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 -30 -20 -10 0 10 20 30 -30 -20 -10 0 10 20 30 Ip (A) Ip (A) 50.0 55.0 60.0 65.0 70.0 75.0 Sens (mV/A)-40 150 TA (°C) -40 TA (°C) 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 Mean Supply Current versus Ambient Temperature VCC = 5 V Supply Current versus Supply Voltage Magnetic Offset Current versus Ambient Temperature Nonlinearity versus Ambient Temperature Mean Total Output Error versus Ambient Temperature Output Voltage versus Sensed Current Sensitivity versus Sensed Current Characteristic Performance IP = 30 A, Sens = 66 mV/A unless otherwise specified

Fully Integrated, Hall Effect-Based Linear Current Sensor with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current ConductorACS712 8Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 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 pro- grammed at the factory to optimize the sensitivity (mV/A) for the full-scale current of the device. Noise (V NOISE). 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 (E LIN). 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: where V IOUT_full-scale amperes = the output voltage (V) when the sensed current approximates full-scale ±IP . Symmetry (ESYM). The degree to which the absolute voltage output from the sensor varies in proportion to either a positive or negative full-scale primary current. The following formula is used to derive symmetry: Quiescent output voltage (V IOUT(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. Electrical offset voltage (V OE). The deviation of the device out- put 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 TOT). The accuracy represents the maximum devia- tion 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. 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 full- scale current flow including temperature effects. Ratiometry. The ratiometric feature means that its 0 A output, V IOUT(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, ΔV IOUT(Q)RAT (%). The ratiometric change in sensitivity, ΔSensRAT (%), is defined as: Definitions of Accuracy Characteristics 100 1– [{ [ { VIOUT_full-scale amperes – VIOUT(Q)Δ gain × % sat ( ) 2 (VIOUT_half-scale amperes – VIOUT(Q) ) 100 VIOUT_+ full-scale amperes – VIOUT(Q) VIOUT(Q) – VIOUT_–full-scale amperes 100 VIOUT(Q)VCC / VIOUT(Q)5V VCC / 5 V 100 SensVCC / Sens5V VCC / 5 V‰ /c144 Output Voltage versus Sensed Current Accuracy at 0 A and at Full-Scale Current Increasing VIOUT(V) +IP (A) Accuracy Accuracy Accuracy 25°C Only Accuracy 25°C Only Accuracy 25°C Only Accuracy 0 A vrOe $Temp erature Average VIOUT –IP (A) vrOe $Temp erature vrOe $Temp erature Decreasing VIOUT(V) IP(min) IP(max) Full Scale

Fully Integrated, Hall Effect-Based Linear Current Sensor with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current ConductorACS712 9Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com Rise Time versus External Filter Capacitance 200 400 600 800 1000 1200 0 100 200 300 400 500 tr(μs) Power on Time versus External Filter Capacitance 100 120 140 160 180 200 01 0 2 0 3 0 4 0 5 0 CF (nF) CF (nF) CF (nF) Expanded in chart at right Rise Time versus External Filter Capacitance 150 200 250 300 350 400 0 50 75 100 125 150 tr(μs) CF (nF) tPO (μs) IP=5 A IP=0 A Noise versus External Filter Capacitance 1000 100 10000 0.01 0.1 1 10 100 1000 Noise(p-p) (mA) Noise vs. Filter Cap Definitions of Dynamic Response Characteristics Propagation delay (tPROP). The time required for the sensor output to reflect a change in the primary current signal. Propaga- tion delay is attributed to inductive loading within the linear IC package, as well as in the inductive loop formed by the primary conductor geometry. Propagation delay can be considered as a fixed time offset and may be compensated. Primary Current Transducer Output I (%) Propagation Time, tPROP t Primary Current Transducer Output I (%) Response Time, tRESPONSE t Primary Current Transducer Output I (%) Rise Time, tr t 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 / t r. Both tr and tRESPONSE are detrimentally affected by eddy current losses observed in the conductive IC ground plane. Response time (tRESPONSE). The time interval between a) when the primary current signal reaches 90% of its final value, and b) when the sensor reaches 90% of its output corresponding to the applied current. Excitation Signal Output (mV) 15 A Step Response TA=25°C CF (nF) t r (μs) 0 6.6 1 7.7 4.7 17.4 10 32.1 22 68.2 47 88.2 100 291.3 220 623.0 470 1120.0

Fully Integrated, Hall Effect-Based Linear Current Sensor with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current ConductorACS712 10Allegro MicroSystems, Inc. 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 V oltage, 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– IP +5 V LMV7235 VIOUT VOUT GND FILTER VCC ACS712 1N914 100 kΩ 33 kΩ RPU 100 kΩ Fault CBYP 0.1 μF CF 1 nF IP+ IP+ IP– IP– +5 V LT1178 2N7002 VIOUT VOUT VPEAK VRESET GND 1N914 VCC ACS712 10 kΩ 1 MΩ 33 kΩ RF 10 kΩ 330 kΩ CBYP 0.1 μF 0.1 μF COUT 0.1 μF CF 1 nF 0.1 μF FILTER IP IP+ IP+ IP– IP– IP +5 V 1N4448W VIOUT VOUT GND

3 FILTER

10 kΩ CBYP 0.1 μF RF 2 kΩ CF 1 nF 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– IP +5 V LM321 VIOUT VOUT GND 1 4 FILTER VCC ACS712 100 kΩ 100 kΩ 3.3 kΩ CBYP 0.1 μF CF 0.01 μF 1000 pF RF 1 kΩ Application 3. This configuration increases gain to 610 mV/A (tested using the ACS712ELC-05A).

Fully Integrated, Hall Effect-Based Linear Current Sensor with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current ConductorACS712 11Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 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 low- pass 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, ∆V ATT , is a result of the resistive divider effect between the resistance of the external filter, RF (see Application 6), and the input impedance and resistance of the customer interface circuit, R INTFC. The transfer function of this resistive divider is given by: 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 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 F (see Application 7) 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 ATT. Therefore, the 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. =∆VATT RINTFC RF + RINTFC VIOUT ⎟⎠ ⎛ . 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, R F, and the resistance of the customer interface circuit, RINTFC. This resistive divider will cause excessive attenuation, as given by the transfer function for ∆V ATT. Application 7. Using the FILTER pin provided on the ACS712 eliminates the attenuation effects of the resistor divider between R F and RINTFC, shown in Appli- cation 6. Application Interface Circuit Resistive Divider RINTFC Low Pass Filter RFAmp Out VCC +5 V Pin 8 Pin 7 VIOUT Pin 6 N.C. Input GND Pin 5 Filter Dynamic Offset Cancellation IP+ IP+ 0.1 MF Pin 1 Pin 2 IP– IP– Pin 3 Pin 4 Gain Temperature Coefficient Offset Voltage Regulator Trim Control To all subcircuits Input VCC Pin 8 Pin 7 VIOUT GND Pin 5 FILTER Pin 6 Dynamic Offset Cancellation IP+ Pin 1 IP+ Pin 2 IP– Pin 3 IP– Pin 4 Sense Trim Signal Recovery Sense Temperature Coefficient Trim +5 V Application Interface Circuit Buffer Amplifier and Resistor RINTFC Allegro ACS712 Allegro ACS706 CF 1 nF CF 1 nF

Fully Integrated, Hall Effect-Based Linear Current Sensor with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current ConductorACS712 12Allegro MicroSystems, Inc. Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 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; 5,686,894; 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 de par tures from the detail spec i fi ca tions as may be required to permit improvements in the per for mance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the information being relied upon is current. The in for ma tion in clud ed herein is believed to be ac cu rate and reliable. How ev er, Allegro MicroSystems, Inc. assumes no re spon si bil i ty for its use; nor for any in fringe ment of patents or other rights of third parties which may result from its use. Copyright ©2006, Allegro MicroSystems, Inc. 0.25 0.10 .010 .004 1.75 1.35 .069 .053 0.51 0.31 .020 .012 4.00 3.80 .157 .150 0.25 0.17 .010 .007 1.27 0.40 .050 .016 5.00 4.80 .197 .189 CSEATING PLANE A B 0.25 [.010] M C A B 6.20 5.80 .244 .228 C0.10 [.004] 0.25 [.010] M B M 1.27 .050 0.25 .010 GAUGE PLANE SEATING PLANE Preliminary dimensions, for reference only Dimensions in millimeters U.S. Customary dimensions (in.) in brackets, for reference only (reference JEDEC MS-012 AA) Dimensions exclusive of mold flash, gate burrs, and dambar protrusions Exact case and lead configuration at supplier discretion within limits shown A Terminal #1 mark area A Package LC, 8-pin SOIC ACS712T RLCPPP YYWWA ACS Allegro Current Sensor

712 Device family number

T Indicator of 100% matte tin leadframe plating R Operating ambient temperature range code PPP Primary sensed current YY Date code: Calendar year (last two digits) WW Date code: Calendar week A Date code: Shift code ACS712T RLCPPP L...L YYWW ACS Allegro Current Sensor T Indicator of 100% matte tin leadframe plating R Operating ambient temperature range code PPP Primary sensed current L...L Lot code YY Date code: Calendar year (last two digits) WW Date code: Calendar week Package Branding Two alternative patterns are used Text 1 Text 2 Text 3 1 For the latest version of this document, go to our website at: www.allegromicro.com