ACS715 Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor FEATURES AND BENEFITS • • • • • • • • • • • • • • • • DESRIPTION Low-noise analog signal path Device bandwidth is set via the FILTER pin 5 µs output rise time in response to step input current 80 kHz bandwidth Total output error 1.5% typical at TA = 25°C Small footprint, low-profile SOIC8 package 1.2 mΩ internal conductor resistance 2.1 kVRMS minimum isolation voltage from pins 1-4 to pins 5-8 5.0 V, single supply operation 133 to 185 mV/A output sensitivity Output voltage proportional to DC currents Factory-trimmed for accuracy Extremely stable output offset voltage Nearly zero magnetic hysteresis Ratiometric output from supply voltage Operating temperature range, –40°C to 150°C The Allegro™ ACS715 provides economical and precise solutions for DC current sensing in automotive systems. The device package allows for easy implementation by the customer. Typical applications include motor control, load detection and management, switch-mode power supplies, and overcurrent fault protection. 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 (>VIOUT(Q)) when an increasing current flows through the primary copper conduction path (from pins 1 and 2, to pins 3 and 4), which is the path used for current 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 the device at up to 5× overcurrent conditions. The terminals of the conductive path are electrically isolated from the signal TÜV America Certificate Number: U8V 06 05 54214 010 Package: *-Pin SOIC (suffix LC) Continued on the next page… Approximate Scale 1:1 1 2 IP IP+ VCC IP+ VIOUT ACS715 3 4 IP– FILTER IP– GND +5 V 8 7 VOUT CBYP 0.1 µF 6 5 CF Typical Application 1. The ACS715 outputs an analog signal, VOUT . that varies linearly with the unidirectional DC primary sampled current, IP , within the range specified. CF is recommended for noise management, with values that depend on the application. ACS715-DS, Rev. 10 Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor ACS715 DESCRIPTION (CONTINUED) leads (pins 5 through 8). This allows the ACS715 to be used in applications requiring electrical isolation without the use of optoisolators or other costly isolation techniques. The ACS715 is provided in a small, surface mount SOIC8 package. The leadframe is plated with 100% matte tin, which is compatible with standard lead (Pb) free printed circuit board assembly processes. Internally, the device is Pb-free, except for flip-chip high-temperature Pb‑based solder balls, currently exempt from RoHS. The device is fully calibrated prior to shipment from the factory. Selection Guide Part Number Optimized Range, IP (A) Sensitivity, Sens (Typ) (mV/A) ACS715ELCTR-20A-T 0 to 20 185 ACS715ELCTR-30A-T 0 to 30 133 ACS715LLCTR-20A-T 0 to 20 185 ACS715LLCTR-30A-T 0 to 30 133 TA (°C) Packing* –40 to 85 Tape and reel, 3000 pieces/reel –40 to 150 *Contact Allegro for additional packing options. 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 Allegro MicroSystems, LLC 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 2 ACS715 Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor SPECIFICATIONS Absolute Maximum Ratings Characteristic Rating Unit VCC 8 V Reverse Supply Voltage VRCC –0.1 V Output Voltage VIOUT 8 V Reverse Output Voltage VRIOUT –0.1 V Output Current Source IOUT(Source) 3 mA 10 mA 100 A Supply Voltage Output Current Sink Symbol IOUT(Sink) Overcurrent Transient Tolerance IP Nominal Operating Ambient Temperature TA Maximum Junction Temperature Storage Temperature Notes 1 pulse, 100 ms Range E –40 to 85 ºC Range L –40 to 150 ºC TJ(max) 165 ºC Tstg –65 to 170 ºC Rating Unit Isolation Characteristics Characteristic Symbol Notes Dielectric Strength Test Voltage* VISO Agency type-tested for 60 seconds per UL standard 60950-1, 1st Edition 2100 VAC Working Voltage for Basic Isolation VWFSI For basic (single) isolation per UL standard 60950-1, 1st Edition 354 VDC or Vpk Working Voltage for Reinforced Isolation VWFRI For reinforced (double) isolation per UL standard 609501, 1st Edition 184 VDC or Vpk * Allegro does not conduct 60-second testing. It is done only during the UL certification process. Allegro MicroSystems, LLC 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 3 Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor ACS715 +5 V VCC (Pin 8) Hall Current Drive IP+ (Pin 1) Sense Temperature Coefficient Trim Dynamic Offset Cancellation IP+ (Pin 2) IP– (Pin 3) Signal Recovery VIOUT (Pin 7) Sense Trim IP– (Pin 4) 0 Ampere Offset Adjust GND (Pin 5) FILTER (Pin 6) Functional Block Diagram IP+ 1 8 VCC IP+ 2 7 VIOUT IP– 3 6 FILTER IP– 4 5 GND Package LC, 8-Pin SOIC Pin-out Diagram Terminal List Table Number Name 1 and 2 IP+ Description Input terminals for current being sampled; fused internally 3 and 4 IP– 5 GND Output terminals for current being sampled; fused internally 6 FILTER Terminal for external capacitor that sets bandwidth 7 VIOUT Analog output signal 8 VCC Signal ground terminal Device power supply terminal Allegro MicroSystems, LLC 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 4 Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor ACS715 COMMON OPERATING CHARACTERISTICS1 over full range of TA, and VCC = 5 V, unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. Max. Units 4.5 5.0 5.5 V mA ELECTRICAL CHARACTERISTICS Supply Voltage Supply Current VCC ICC VCC = 5.0 V, output open – 10 13 Output Capacitance Load CLOAD VIOUT to GND – – 10 nF Output Resistive Load RLOAD VIOUT to GND 4.7 – – kΩ mΩ Primary Conductor Resistance RPRIMARY TA = 25°C – 1.2 – Rise Time tr IP = IP(max), TA = 25°C, COUT = 10 nF – 3.5 – μs Frequency Bandwidth f –3 dB, TA = 25°C; IP is 10 A peak-to-peak – 80 – kHz Over full range of IP , IP applied for 5 ms – ±1.5 – % Unidirectional; IP = 0 A, TA = 25°C – VCC × 0.1 – V Output reaches 90% of steady-state level, no capacitor on FILTER pin; TJ = 25; 20 A present on leadframe – 35 – µs 12 – G/A Nonlinearity Zero Current Output Voltage Power-On Time Magnetic ELIN VIOUT(Q) tPO Coupling2 Internal Filter Resistance3 – RF(INT) 1.7 kΩ 1Device may be operated at higher primary current levels, IP, and ambient, TA , and internal leadframe temperatures, TA , provided that the Maximum Junction Temperature, TJ(max), is not exceeded. 21G = 0.1 mT. 3R F(INT) forms an RC circuit via the FILTER pin. COMMON THERMAL CHARACTERISTICS1 Operating Internal Leadframe Temperature TA Min. Typ. Max. Units E range –40 – 85 °C L range –40 – 150 °C Value Units Junction-to-Lead Thermal Resistance2 RθJL Mounted on the Allegro ASEK 715 evaluation board 5 °C/W Junction-to-Ambient Thermal Resistance2,3 RθJA Mounted on the Allegro 85-0322 evaluation board, includes the power consumed by the board 23 °C/W 1Additional thermal information is available on the Allegro website. evaluation board has 1500 mm2 of 2 oz. copper on each side, connected to pins 1 and 2, and to pins 3 and 4, with thermal vias connecting the layers. Performance values include the power consumed by the PCB. Further details on the board are available from the Frequently Asked Questions document on our website. Further information about board design and thermal performance also can be found in the Applications Information section of this datasheet. 3R θJA values shown in this table are typical values, measured on the Allegro evaluation board. The actual thermal performance depends on the actual application board design, the airflow in the application, and thermal interactions between the device and surrounding components through the PCB and the ambient air. To improve thermal performance, see our applications material on the Allegro website. 2The Allegro Allegro MicroSystems, LLC 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 5 Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor ACS715 x20A PERFORMANCE CHARACTERISTICS over Range E: TA = –40°C to 85°C1, CF = 1 nF, and VCC = 5 V, unless otherwise specified Characteristic Optimized Accuracy Range Sensitivity Symbol Test Conditions IP Sens Over full range of IP, IP applied for 5 ms; TA = 25°C Noise Peak-to-peak, TA = 25°C, 2 kHz external filter, 185 mV/A VNOISE(PP) programmed Sensitivity, CF = 47 nF, COUT = 10 nF, 2 kHz bandwidth Zero Current Output Slope ∆VOUT(Q) Sensitivity Slope ∆Sens Min. Typ. Max. Units 0 – 20 A 178 185 190 mV/A – 21 – mV mV/°C TA = –40°C to 25°C – 0.08 – TA = 25°C to 150°C – 0.16 – mV/°C TA = –40°C to 25°C – 0.035 – mV/A/°C TA = 25°C to 150°C Electrical Output Voltage VOE IP = 0 A Total Output Error2 ETOT IP = 20 A , IP applied for 5 ms; TA = 25°C – 0.019 – mV/A/°C –40 – 40 mV – ±1.5 – % 1Device may be operated at higher primary current levels, IP, and ambient temperatures, TA, provided that the Maximum Junction Temperature, TJ(max), is not exceeded. 2Percentage of I , with I = 20 A. Output filtered. P P x20A PERFORMANCE CHARACTERISTICS over Range L: TA = –40°C to 150°C1, CF = 1 nF, and VCC = 5 V, unless otherwise specified Characteristic Optimized Accuracy Range Sensitivity Symbol IP Sens Noise VNOISE(PP) Zero Current Output Slope ∆VOUT(Q) Sensitivity Slope Electrical Output Voltage Total Output Error2 Test Conditions ∆Sens VOE ETOT Over full range of IP, IP applied for 5 ms; TA = 25°C Over full range of IP, TA = –40°C to 150°C Min. Typ. Max. Units 0 – 20 A – 185 – mV/A 161 – 194 mV/A Peak-to-peak, TA = 25°C, 2 kHz external filter, 185 mV/A programmed Sensitivity, CF = 47 nF, COUT = 10 nF, 2 kHz bandwidth – 21 – mV mV/°C TA = –40°C to 25°C – 0.08 – TA = 25°C to 150°C – 0.16 – mV/°C TA = –40°C to 25°C – 0.035 – mV/A/°C TA = 25°C to 150°C – 0.019 – mV/A/°C –60 – 60 mV IP = 20 A , IP applied for 5 ms; TA = 25°C – ±1.5 – % IP = 20 A , IP applied for 5 ms; TA = –40°C to 150°C –6 – 6 % IP = 0 A 1Device may be operated at higher primary current levels, IP, and ambient temperatures, TA, provided that the Maximum Junction Temperature, TJ(max), is not exceeded. 2Percentage of I , with I = 20 A. Output filtered. P P Allegro MicroSystems, LLC 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 6 Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor ACS715 x30A PERFORMANCE CHARACTERISTICS over Range E: TA = –40°C to 85°C1, CF = 1 nF, and VCC = 5 V, unless otherwise specified Characteristic Optimized Accuracy Range Sensitivity Symbol Test Conditions IP Sens Over full range of IP, IP applied for 5 ms; TA = 25°C Noise Peak-to-peak, TA = 25°C, 2 kHz external filter, 133 mV/A VNOISE(PP) programmed Sensitivity, CF = 47 nF, COUT = 10 nF, 2 kHz bandwidth Zero Current Output Slope ∆VOUT(Q) Sensitivity Slope ∆Sens Min. Typ. Max. Units 0 – 30 A 129 133 137 mV/A – 15 – mV mV/°C TA = –40°C to 25°C – 0.06 – TA = 25°C to 150°C – 0.1 – mV/°C TA = –40°C to 25°C – 0.007 – mV/A/°C TA = 25°C to 150°C Electrical Output Voltage VOE IP = 0 A Total Output Error2 ETOT IP = 30 A , IP applied for 5 ms; TA = 25°C – –0.025 – mV/A/°C –30 – 30 mV – ±1.5 – % 1Device may be operated at higher primary current levels, IP, and ambient temperatures, TA, provided that the Maximum Junction Temperature, TJ(max), is not exceeded. 2Percentage of I , with I = 30 A. Output filtered. P P x30A PERFORMANCE CHARACTERISTICS over Range L: TA = –40°C to 150°C1, CF = 1 nF, and VCC = 5 V, unless otherwise specified Characteristic Optimized Accuracy Range Sensitivity Symbol IP Sens Noise VNOISE(PP) Zero Current Output Slope ∆VOUT(Q) Sensitivity Slope Electrical Output Voltage Total Output Error2 Test Conditions ∆Sens VOE ETOT Over full range of IP, IP applied for 5 ms; TA = 25°C Over full range of IP, TA = –40°C to 150°C Min. Typ. Max. Units 0 – 30 A – 133 – mV/A 125 – 137 mV/A Peak-to-peak, TA = 25°C, 2 kHz external filter, 133 mV/A programmed Sensitivity, CF = 47 nF, COUT = 10 nF, 2 kHz bandwidth – 15 – mV mV/°C TA = –40°C to 25°C – 0.06 – TA = 25°C to 150°C – 0.1 – mV/°C TA = –40°C to 25°C – 0.007 – mV/A/°C TA = 25°C to 150°C – –0.025 – mV/A/°C IP = 0 A, TA = 25ºC –40 – 40 mV IP = 0 A, TA = –40ºC to 150ºC –60 – 60 mV IP = 30 A , IP applied for 5 ms; TA = 25°C – ±1.5 – % IP = 30 A , IP applied for 5 ms; TA = –40°C to 150°C –5 – 5 % 1Device may be operated at higher primary current levels, IP, and ambient temperatures, TA, provided that the Maximum Junction Temperature, TJ(max), is not exceeded. 2Percentage of I , with I = 30 A. Output filtered. P P Allegro MicroSystems, LLC 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 7 Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor ACS715 CHARACTERISTIC PERFORMANCE IP = 20 A, unless otherwise specified Mean Supply Current versus Ambient Temperature 10.5 11.2 10.4 11.0 10.2 10.8 VCC = 5 V ICC (mA) Mean ICC (mA) 10.3 10.1 10.0 9.9 10.6 10.4 10.2 9.8 10.0 9.7 9.8 9.6 -50 -25 0 25 Supply Current versus Supply Voltage 50 75 100 125 9.6 4.5 150 4.6 4.7 4.8 4.9 TA (°C) Magnetic Offset versus Ambient Temperature 5.5 0.25 –1.5 –2.0 –2.5 ELIN (%) IOM (mA) 5.4 0.30 –1.0 VCC = 5 V; IP = 0 A, After excursion to 20 A –3.0 –3.5 0.20 0.15 0.10 –4.0 0.05 –4.5 –5.0 -50 -25 0 25 50 75 100 125 0 –50 150 –25 0 25 75 50 100 125 150 TA (°C) TA (°C) Mean Total Output Error versus Ambient Temperature 10 Sensitivity versus Ambient Temperature 188 8 187 6 Sens (mV/A) 4 ETOT (%) 5.3 Nonlinearity versus Ambient Temperature –0.5 2 0 –2 –4 186 185 184 183 –6 –8 –50 182 –25 0 25 75 50 100 125 150 –50 –25 0 25 TA (°C) Output Voltage versus Sensed Current 4.5 4.0 3.0 Sens (mV/A) VCC = 5 V 3.5 TA (°C) –40 –20 25 85 125 2.5 2.0 1.5 1.0 0.5 0 0 5 10 15 20 25 200.00 198.00 196.00 194.00 192.00 190.00 188.00 186.00 184.00 182.00 180.00 178.00 176.00 174.00 525 125 150 TA (°C) –40 25 85 150 0 5 10 15 Ip (A) 20 25 0 A Output Voltage Current versus Ambient Temperature 0.140 0.120 520 0.100 IP = 0 A IP = 0 A 0.080 IOUT(Q) (A) 515 510 505 500 0.060 0.040 0.020 0 495 490 -50 100 Sensitivity versus Sensed Current IP (A) 0 A Output Voltage versus Ambient Temperature 75 50 TA (°C) 5.0 VIOUT (V) 5.2 0.35 0 VIOUT(Q) (mV) 5.0 5.1 VCC (V) -0.020 -25 0 25 50 TA (°C) 75 100 125 150 -0.040 -50 -25 0 25 50 75 100 125 150 TA (°C) Allegro MicroSystems, LLC 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 8 Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor ACS715 CHARACTERISTIC PERFORMANCE IP = 30 A, unless otherwise specified Mean Supply Current versus Ambient Temperature 10.1 10.8 10.0 10.6 ICC (mA) Mean ICC (mA) 9.9 VCC = 5 V 90.8 9.7 10.4 10.2 10.0 9.6 9.8 9.5 9.6 9.4 -50 -25 0 25 50 75 100 125 Supply Current versus Supply Voltage 9.4 4.5 150 4.6 4.7 4.8 4.9 TA (°C) –0.5 IOM (mA) 5.5 0.25 –1.5 –2.5 ELIN (%) –2.0 VCC = 5 V; IP = 0 A, After excursion to 20 A –3.0 –3.5 –4.0 0.20 VCC = 5 V 0.15 0.10 0.05 –4.5 –5.0 -50 -25 0 25 50 75 100 125 0 –50 150 Mean Total Output Error versus Ambient Temperature 133.5 6 133.0 Sens (mV/A) 8 4 2 0 130.5 –6 130.0 25 75 50 100 125 129.5 –50 150 Output Voltage versus Sensed Current 4.5 Sens (mV/A) 4.0 VCC = 5 V 3.0 TA (°C) –40 –20 25 85 125 2.5 2.0 1.5 1.0 0.5 5 10 15 20 25 30 35 IP (A) 0 A Output Voltage versus Ambient Temperature 514 150 –25 0 25 75 50 100 125 150 140 139 138 137 136 135 134 133 132 131 130 129 128 127 126 125 Sensitivity versus Sensed Current TA (°C) –40 25 85 150 0 5 10 15 25 20 Ip (A) 30 35 0 A Output Voltage Current versus Ambient Temperature 0.080 512 0.060 510 IP = 0 A 508 IOUT(Q) (A) 506 504 502 500 498 IP = 0 A 0.040 0.020 0 -0.020 496 494 -50 125 TA (°C) 5.0 0 100 Sensitivity versus Ambient Temperature TA (°C) 3.5 75 50 131.5 131.0 0 25 132.0 –4 –25 0 132.5 –2 –8 –50 –25 TA (°C) TA (°C) VIOUT (V) 5.4 0.30 –1.0 VIOUT(Q) (mV) 5.3 0.35 0 0 5.2 Nonlinearity versus Ambient Temperature Magnetic Offset versus Ambient Temperature ETOT (%) 5.0 5.1 VCC (V) -25 0 25 50 TA (°C) 75 100 125 150 -0.040 -50 -25 0 25 50 75 100 125 150 TA (°C) Allegro MicroSystems, LLC 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 9 ACS715 Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor DEFINITIONS OF ACCURACY CHARACTERISTICS 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 (VNOISE). The product of the linear IC amplifier gain (mV/G) and the noise floor for the Allegro Hall effect linear IC (≈1 G). The noise floor is derived from the thermal and shot noise observed in Hall elements. Dividing the noise (mV) by the sensitivity (mV/A) provides the smallest current that the device is able to resolve. Linearity (ELIN). The degree to which the voltage output from the 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 1– (VIOUT_full-scale amperes –VIOUT(Q) ) 2 (VIOUT_half-scale amperes – VIOUT(Q)) [{ Accuracy is divided into four areas: • 0 A at 25°C. Accuracy 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 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. Ratiometry. The ratiometric feature means that its 0 A output, VIOUT(Q), (nominally equal to VCC × 0.1) and sensitivity, Sens, are proportional to its supply voltage, VCC . The following formula is used to derive the ratiometric change in 0 A output voltage, ΔVIOUT(Q)RAT (%). 100 VIOUT(Q)VCC / VIOUT(Q)5V VCC / 5 V The ratiometric change in sensitivity, ΔSensRAT (%), is defined as: 100 where VIOUT_full-scale amperes = the output voltage (V) when the sampled current approximates full-scale ±IP . Quiescent output voltage (VIOUT(Q)). The output of the device when the primary current is zero. For a unipolar supply voltage, it nominally remains at VCC × 0.1 . Thus, VCC = 5 V translates into VIOUT(Q) = 0.5 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 (VOE). The deviation of the device output from its ideal quiescent value of VCC × 0.1 due to nonmagnetic causes. To convert this voltage to amperes, divide by the device sensitivity, Sens. Accuracy (ETOT). The accuracy represents the maximum deviation of the actual output from its ideal value. This is also known as the total output error. The accuracy is illustrated graphically in the output voltage versus current chart at right. SensVCC / Sens5V VCC / 5 V Increasing VIOUT(V) Accuracy Over ∆Temp erature Accuracy 25°C Only Average VIOUT Accuracy Over ∆Temp erature Accuracy 25°C Only 30 A –IP (A) +IP (A) Full Scale 0A Decreasing VIOUT(V) Figure 1: Output Voltage versus Sampled Current Accuracy at 0 A and at Full-Scale Current 10 Allegro MicroSystems, LLC 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor ACS715 DEFINITIONS OF DYNAMIC RESPONSE CHARACTERISITCS Power-On Time (tPO). When the supply is ramped to its operating voltage, the device requires a finite time to power its internal components before responding to an input magnetic field. Power-On Time, tPO , is defined as the time it takes for the output voltage to settle within ±10% of its steady state value under an applied magnetic field, after the power supply has reached its minimum specified operating voltage, VCC(min), as shown in the chart at right. Figure 2: Power-On Time 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 tRESPONSE are detrimentally affected by eddy current losses observed in the conductive IC ground plane. Primary Current I (%) 90 Transducer Output 10 0 t Rise Time, tr Noise vs. Filter Cap Power on Time versus External Filter Capacitance 10000 IP = 5 A IP = 0 A 0 1200 10 20 CF (nF) 30 40 Rise Time versus External Filter Capacitance CF (nF) Open 1 4.7 22 47 100 220 470 Expanded in chart at right } tr(µs) 800 400 200 0 0.1 1 10 CF (nF) 100 1000 100 10 1 0.01 50 1000 600 Noise versus External Filter Capacitance 1000 Noise(p-p) (mA) 200 180 160 140 120 100 80 60 40 20 0 tr (µs) 3.5 5.8 17.5 73.5 88.2 291.3 623 1120 tr(µs) tPO (µs) Figure 3: Rise Time 180 160 140 120 100 80 60 40 20 0 0.1 0.1 1 CF (nF) 10 100 1000 Rise Time versus External Filter Capacitance 1 CF (nF) 10 100 Figure 4: Power-On and Rise Time Characteristics 11 Allegro MicroSystems, LLC 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor ACS715 CHOPPER STABILIZATION TECHNIQUE Sample and Hold This technique is made possible through the use of a BiCMOS Chopper Stabilization is an innovative circuit technique that is used to minimize the offset voltage of a Hall element and an asso- process that allows the use of low-offset and low-noise amplifiers ciated on-chip amplifier. Allegro patented a Chopper Stabilizain combination with high-density logic integration and sample tion technique that nearly eliminates Hall IC output drift induced and hold circuits. by temperature or package stress effects. This offset reduction +5 V VS1 Regulator technique is based on a signal modulation-demodulation process. Modulation is used to separate the undesired DC offset signal CBYP 0.1 µF Clock/Logic from the magnetically induced signal in the frequency domain. 8 1 VCC IP+ Low-Pass U1 Then, using a low-pass filter, the modulated DC offset is sup7 VElement Hall + OUT 2 LMC6772 Filter IP+ VIOUT pressed while the magnetically induced signal passes through VREF – ACS715 IP1 the Amp the filter. As a result of this chopper stabilization approach, 6 3 FILTER output voltage from the Hall IC is desensitized to the effects4 IP– CF IP– of temperature and mechanical stress. This technique produces GND 5 Q3 devices that have an extremely stable Electrical Offset Voltage, 2N7002 are immune to thermal stress, and have precise recoverability R3 Q1 10 kΩ FDS6675a after temperature cycling. R1 100 kΩ Figure 5: Concept of Chopper Stabilization Technique VS2 +5 V CBYP 0.1 µF 1 2 IP IP+ R1 33 kΩ VCC IP+ VIOUT ACS715 3 4 IP– FILTER IP– GND 8 7 1 VOUT IP2 4 3 6 5 CF 2 RPU 100 kΩ R2 100 kΩ – + 5 +5 V VCC IP+ IP+ VIOUT IP– FILTER Fault 4 IP– 1 GND 2 U1 LMV7235 6 – 8 5 IP Q4 6 2N7002 IP– FILTER 4R4 10IP– kΩ GND 5 R2 100 kΩ Application 2. 10 A Overcurrent Fault Latch. Fault threshold set by R1 and R2. This circuit latches an overcurrent fault and holds it until the 5 V rail is powered down. 2 IP1 VCC IP+ VIOUT ACS715 3 4 IP– FILTER IP– GND 3 – LM321 5 VOUT 4 2 C1 1000 pF R3 3.3 kΩ CF 0.01 µF +5 V IP+ + Application 3. This configuration increases gain to 610 mV/A (tested using the ACS712ELC-05A). VS1 1 1 RF 1 kΩ ACS715 3 D1 1N914 R2 100 kΩ 1 VCC IP+ CF 7 2 IP+ VIOUT Q2 FDS6675a Application 4. Control circuit for MOSFET ORing. R1 100 kΩ U2 LMC6772 + 7 VOUT VREF ACS715 3 CBYP CBYP 0.1 µF 0.1 µF 8 LOAD +5 V CBYP 0.1 µF 8 VREF 1 U1 LMC6772 + 7 VOUT – 2 IP2 6 5 +5 V VS2 CF IP+ VCC IP+ VIOUT ACS715 3 4 IP– FILTER IP– GND CBYP 0.1 µF 8 + 7 VOUT VREF – 6 5 CF Q3 2N7002 Q1 FDS6675a U2 LMC6772 Q4 2N7002 Q2 FDS6675a R3 10 kΩ R4 10 kΩ R2 100 kΩ R1 100 kΩ LOAD Figure 6: Typical Applications 12 Allegro MicroSystems, LLC 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor ACS715 IMPROVING SENSING SYSTEM ACCURACY USING THE FILTER PIN In low-frequency sensing applications, it is often advantageous to add a simple RC filter to the output of the device. Such a lowpass 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, ∆VATT , is a result of the resistive divider effect between the resistance of the external filter, RF (see Application 5), and the input impedance and resistance of the customer interface circuit, RINTFC. The transfer function of this resistive divider is given by: RINTFC RF + RINTFC ∆VATT = VIOUT . Even if RF and RINTFC are designed to match, the two individual resistance values will most likely drift by different amounts over temperature. Therefore, signal attenuation will vary as a function of temperature. Note that, in many cases, the input impedance, RINTFC , of a typical analog-to-digital converter (ADC) can be as low as 10 kΩ. The ACS715 contains an internal resistor, a FILTER pin connection to the printed circuit board, and an internal buffer amplifier. With this circuit architecture, users can implement a simple RC filter via the addition of a capacitor, CF (see Application 6) from the FILTER pin to ground. The buffer amplifier inside of the ACS715 (located after the internal resistor and FILTER pin connection) eliminates the attenuation caused by the resistive divider effect described in the equation for ∆VATT. Therefore, the ACS715 device is ideal for use in high-accuracy applications that cannot afford the signal attenuation associated with the use of an external RC low-pass filter. +5 V Pin 3 Pin 4 IP– IP– VCC Pin 8 Allegro ACS706 Voltage Regulator To all subcircuits Filter 0.1 µF Resistive Divider VIOUT Pin 7 Dynamic Offset Cancellation Application 5. When a low pass filter is constructed externally to a standard Hall effect device, a resistive divider may exist between the filter resistor, RF, and the resistance of the customer interface circuit, RINTFC. This resistive divider will cause excessive attenuation, as given by the transfer function for ∆VATT. Amp Out N.C. Pin 6 Input RF Application Interface Circuit Low Pass Filter Temperature Coefficient Gain Offset CF RINTFC Trim Control GND Pin 5 IP+ IP+ Pin 1 Pin 2 +5 V VCC Pin 8 Allegro ACS715 IP+ Pin 1 IP+ Pin 2 IP– Pin 3 IP– Pin 4 Sense Temperature Coefficient Trim Buffer Amplifier and Resistor Dynamic Offset Cancellation Application 6. Using the FILTER pin provided on the ACS715 eliminates the attenuation effects of the resistor divider between RF and RINTFC, shown in Application 5. Hall Current Drive Signal Recovery VIOUT Pin 7 Input Application Interface Circuit Sense Trim 0 Ampere Offset Adjust RINTFC GND Pin 5 FILTER Pin 6 CF Figure 7: Typical Applications 13 Allegro MicroSystems, LLC 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor ACS715 PACKAGE OUTLINE DRAWING For Reference Only – Not for Tooling Use (Reference MS-012AA) 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 8° 0° 4.90 ±0.10 1.27 0.65 8 8 0.25 0.17 3.90 ±0.10 5.60 6.00 ±0.20 A 1.04 REF 1 1.75 2 1 1.27 0.40 C 2 PCB Layout Reference View 0.25 BSC SEATING PLANE Branded Face GAUGE PLANE C 8X 0.10 1.75 MAX C NNNNNNN SEATING PLANE PPT-AAA LLLLL 0.51 0.31 0.25 0.10 1.27 BSC 1 A Terminal #1 mark area B Branding scale and appearance at supplier discretion C Reference land pattern layout (reference IPC7351 SOIC127P600X175-8M); all pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary to meet application process requirements and PCB layout tolerances. B Standard Branding Reference View N = Device part number P = Package Designator T = Device temperature range A = Amperage L = Lot number Belly Brand = Country of Origin Figure 8: Package LC, 8-pin SOIC 14 Allegro MicroSystems, LLC 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com Automotive Grade, Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 2.1 kVRMS Voltage Isolation and a Low-Resistance Current Conductor ACS715 Revision History Revision Revision Date 9 November 16, 2014 10 June 24, 2015 Description of Revision Update rise time and isolation, IOUT reference data, patents Revised performance characteristics Copyright ©2006-2015, 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. For the latest version of this document, go to our website at: www.allegromicro.com 15 Allegro MicroSystems, LLC 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com