ACS716 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection Features and Benefits Description Industry-leading noise performance with greatly improved bandwidth through proprietary amplifier and filter design techniques Small footprint package suitable for space-constrained applications 1 m primary conductor resistance for low power loss High isolation voltage, suitable for line-powered applications User-adjustable Overcurrent Fault level Overcurrent Fault signal typically responds to an overcurrent condition in < 2 s Integrated shield virtually eliminates capacitive coupling from current conductor to die due to high dV/dt voltage transients Filter pin capacitor improves resolution in low bandwidth applications 3 to 3.6 V, single supply operation Factory trimmed sensitivity and quiescent output voltage Chopper stabilization results in extremely stable quiescent output voltage Ratiometric output from supply voltage The Allegro(R) ACS716 current sensor provides economical and precise means for current sensing applications in industrial, commercial, and communications systems. The device is offered in a small footprint surface mount package that allows easy implementation in customer applications. Package: 16-pin SOIC Hall Effect IC Package (suffix LA) The ACS716 consists of a precision linear Hall sensor integrated circuit with a copper conduction path located near the surface of the silicon die. Applied current flows through the copper conduction path, and the analog output voltage from the Hall sensor linearly tracks the magnetic field generated by the applied current. The accuracy of the ACS716 is maximized with this patented packaging configuration because the Hall element is situated in extremely close proximity to the current to be measured. High level immunity to current conductor dV/dt and stray electric fields, offered by Allegro proprietary integrated shield technology, guarantees low ripple at output and low offset drift in high-side, high voltage applications. The voltage on the Overcurrent Input (VOC pin) allows customers to define an overcurrent fault threshold for the device. When the current flowing through the copper conduction path (between the IP+ and IP- pins) exceeds this threshold, the open drain Overcurrent Fault pin will transition to a logic low state. Factory programming of the linear Hall sensor inside of the ACS716 results in exceptional accuracy in both analog and digital output signals. The internal resistance of the copper path used for current sensing is typically 1 m, for low power loss. Also, the current conduction path is electrically isolated from the low voltage Approximate Scale 1:1 1 2 3 4 IP 5 6 7 8 IP+ IP+ IP+ IP+ FAULT_EN ACS716 VOC VCC FAULT IP- VIOUT IP- FILTER IP- VZCR IP- GND ACS716-DS, Rev. 2 16 Fault_EN Continued on the next page... RH VCC 15 RH, RL 14 CF RL RPU 13 12 11 COC CF 1 nF A Noise and bandwidth limiting filter capacitor Fault delay setting capacitor, 22 nF maximum A Use of capacitor required B Use of resistor optional, 330 k recommended. If used, resistor must be connected between AULT pin and VCC. F VIOUT 10 9 COC 0.1 F B Sets resistor divider reference for VOC 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection ACS716 Description (continued) sensor inputs and outputs. This allows the ACS716 family of sensors to be used in applications requiring electrical isolation, without the use of opto-isolators or other costly isolation techniques. Pb-based solder balls, currently exempt from RoHS. The device is fully calibrated prior to shipment from the factory. The ACS716 is provided in a small, surface mount SOIC16 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 Applications include: * Motor control and protection * Load management and overcurrent detection * Power conversion and battery monitoring / UPS systems Selection Guide Part Number Sens (typ) at VCC = 3.3 V (mV/A) IP (A) ACS716KLATR-6BB-T2 6 ACS716KLATR-12CB-T2 ACS716KLATR-25CB-T2 TA (C) Packing1 100 -40 to 125 Tape and Reel, 1000 pieces per reel 12 37 -40 to 125 Tape and Reel, 1000 pieces per reel 25 18.5 -40 to 125 Tape and Reel, 1000 pieces per reel 1Contact Allegro 2Variant for packing options. not intended for automotive applications. Absolute Maximum Ratings Characteristic Symbol Supply Voltage Notes Rating Units 8 V VCC Filter Pin VFILTER 8 V Analog Output Pin VIOUT 32 V Overcurrent Input Pin VOC 8 V V FAULT 8 V Fault Enable (FAULT_EN) Pin VFAULTEN 8 V Voltage Reference Output Pin VZCR 8 V DC Reverse Voltage: VCC, FILTER, VIOUT, VOC, AULT , FAULT_EN, and VZCR Pins F VRdcx -0.5 V Rated Dielectric Insulation Voltage VISO 60 Hz AC, 1 minute at TA = 25C 3000 VAC For single protection according to UL 1577 standard; for higher continuous voltage ratings, please contact Allegro 277 VAC Voltage by which pin voltage can exceed the VCC pin voltage 0.3 V 3 mA AULT Pin Overcurrent F Rated Continuous Voltage on Primary Leads (IP+ and IP-) VWORKING Excess to Supply Voltage: FILTER, VIOUT, VOC, AULT , FAULT_EN, and VZCR Pins F Output Current Source VEX IIOUT(Source) Output Current Sink IIOUT(Sink) Operating Ambient Temperature TA Range K 1 mA -40 to 125 C Junction Temperature TJ(max) 165 C Storage Temperature Tstg -65 to 170 C Thermal Characteristics Characteristic Package Thermal Resistance Symbol RJA Test Conditions Value Units When mounted on Allegro demo board with 1332 mm2 (654 mm2 on component side and 678 mm2 on opposite side) of 2 oz. copper connected to the primary leadframe and with thermal vias connecting the copper layers. Performance is based on current flowing through the primary leadframe and includes the power consumed by the PCB. 17 Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com C/W 2 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection ACS716 Functional Block Diagram VCC Hall Bias FAULT_EN D Q CLK R POR POR Fault Latch FAULT Reset Drain - VOC + 2VREF OC Fault Control Logic FAULT 3 mA Fault Comparator - Sensitivity Trim VZCR + IP+ VIOUT Signal Recovery RF(INT) Hall Amplifier IP- VOUT(Q) Trim GND FILTER Terminal List Table Number Pin-out Diagram IP+ 1 16 FAULT_EN IP+ 2 15 VOC IP+ 3 14 VCC IP+ 4 13 FAULT IP- 5 12 VIOUT IP- 6 11 FILTER IP- 7 10 VZCR IP- 8 9 GND Name Description 1 through 4 IP+ Sensed current copper conduction path pins. Terminals for current being sensed; fused internally, loop to IP- pins; unidirectional or bidirectional current flow. 5 through 8 IP- Sensed current copper conduction path pins. Terminals for current being sensed; fused internally, loop to IP+ pins; unidirectional or bidirectional current flow. 9 GND Device ground connection. 10 VZCR Voltage Reference Output pin. Zero current (0 A) reference; output voltage on this pin scales with VCC . (Not a highly accurate reference.) 11 FILTER Filter pin. Terminal for an external capacitor connected from this pin to GND to set the device bandwidth. 12 VIOUT Analog Output pin. Output voltage on this pin is proportional to current flowing through the loop between the IP+ pins and IP- pins. 13 AULT F Overcurrent Fault pin. When current flowing between IP+ pins and IP- pins exceeds the overcurrent fault threshold, this pin transitions to a logic low state. 14 VCC Supply voltage. 15 VOC Overcurrent Input pin. Analog input voltage on this pin sets the overcurrent fault threshold. 16 AULT when low. FAULT_EN Enables overcurrent faulting when high. Resets F Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 3 ACS716 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection COMMON OPERATING CHARACTERISTICS Valid at TA = -40C to 125C, VCC = 3.3 V, unless otherwise specified Characteristic ELECTRICAL CHARACTERISTICS Supply Voltage Nominal Supply Voltage Supply Current Output Capacitance Load Output Resistive Load Magnetic Coupling from Device Conductor to Hall Element Internal Filter Resistance1 Symbol Test Conditions Min. Typ. Max. Units 3 - - 3.3 3.6 - V V AULT pin high VIOUT open, F VIOUT pin to GND VIOUT pin to GND - - 10 9 - - 11 10 - mA nF k Current flowing from IP+ to IP- pins - 9.5 - G/A VCC VCCN ICC CLOAD RLOAD MCHALL - 1.7 - k Primary Conductor Resistance RPRIMARY ANALOG OUTPUT SIGNAL CHARACTERISTICS Full Range Linearity2 ELIN Symmetry3 ESYM TA = 25C - 1 - m IP = IP0A IP = IP0A -0.75 99.1 0.25 100 0.75 100.9 % % Bidirectional Quiescent Output VOUT(QBI) TIMING PERFORMANCE CHARACTERISTICS IP = 0 A, TA = 25C - VCCx0.5 - V - 3 - s - 1 - s - 4 - s - 120 - kHz - 35 - s VOC VCCx0.25 - VCCx0.4 V INCOMP - 1 - A Switchpoint in VOC safe operating area; assumes INCOMP = 0 A - 5 - % AULT pin 1 mA sink current at F - - 0.4 V - - 0.1 x VCC V VIOUT Signal Rise Time VIOUT Signal Propagation Time RF(INT) tr tPROP VIOUT Signal Response Time tRESPONSE VIOUT Large Signal Bandwidth f3dB Power-On Time tPO OVERCURRENT CHARACTERISTICS Setting Voltage for Overcurrent Switchpoint4 Signal Noise at Overcurrent Comparator Input Overcurrent Fault Switchpoint Error5,6 EOC AULT Pin Output Voltage Overcurrent F V FAULT Fault Enable (FAULT_EN Pin) Input Low Voltage Threshold VIL TA = 25C, Swing IP from 0 A to IP0A, no capacitor on FILTER pin, 100 pF from VIOUT to GND TA = 25C, no capacitor on FILTER pin, 100 pF from VIOUT to GND TA = 25C, Swing IP from 0 A to IP0A, no capacitor on FILTER pin, 100 pF from VIOUT to GND -3 dB, Apply IP such that VIOUT = 1 Vpk-pk, no capacitor on FILTER pin, 100 pF from VIOUT to GND Output reaches 90% of steady-state level, no capacitor on FILTER pin, TA = 25C Continued on the next page... Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 4 ACS716 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection COMMON OPERATING CHARACTERISTICS (continued) Valid at TA = -40C to 125C, VCC = 3.3 V, unless otherwise specified Characteristic Symbol OVERCURRENT CHARACTERISTICS (continued) Test Conditions Min. Typ. Max. Units Fault Enable (FAULT_EN Pin) Input High Voltage Threshold VIH 0.8 x VCC - - V Fault Enable (FAULT_EN Pin) Input Resistance RFEI - 1 - M - 15 - s - 2 - s - 500 - ns - 250 - ns 2 - - M 0.48 x VCC 0.5 x VCC 0.52 x VCC V 3 50 - - - 10 - - - mA A mV Fault Enable (FAULT_EN Pin) Delay7 tFED Overcurrent Fault Response Time tOC Overcurrent Fault Reset Delay tOCR Overcurrent Fault Reset Hold Time tOCH Overcurrent Input Pin Resistance VOLTAGE REFERENCE CHARACTERISTICS ROC Voltage Reference Output VZCR Voltage Reference Output Load Current IZCR Voltage Reference Output Drift VZCR Set FAULT_EN to low, VOC = 0.25 x VCC , COC = 0 F; then run a DC IP exceeding the corresponding overcurrent threshold; then reset FAULT_EN from low to high and measure the delay from the rising edge of AULT FAULT_EN to the falling edge of F FAULT_EN set to high for a minimum of 20 s before the overcurrent event; switchpoint set at VOC = 0.25 x VCC ; apply a current step to IP with amplitude equal to 1.5 x VOC/ Sens; delay from IP exceeding overcurrent fault threshold to V FAULT < 0.4 V, without external COC capacitor Time from VFAULTEN < VIL to VFAULT > 0.8 x VCC , RPU = 330 k Time from VFAULTEN pin < VIL to reset of fault latch; see Functional Block Diagram TA = 25C, VOC pin to GND TA = 25 C (Not a highly accurate reference) Source current Sink current 1R F(INT) forms an RC circuit via the FILTER pin. 2This parameter can drift by as much as 0.8% over the lifetime of this product. parameter can drift by as much as 1% over the lifetime of this product. 4See page 8 on how to set overcurrent fault switchpoint. 5Switchpoint can be lower at the expense of switchpoint accuracy. 6This error specification does not include the effect of noise. See the I NCOMP specification in order to factor in the additional influence of noise on the fault switchpoint. 7Fault Enable Delay is designed to avoid false tripping of an Overcurrent (OC) fault at power-up. A 15 s (typical) delay will always be needed, every time FAULT_EN is raised from low to high, before the device is ready for responding to any overcurrent event. 3This Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 5 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection ACS716 PERFORMANCE CHARACTERISTICS, TA Range K, valid at TA = - 40C to 125C, VCC = 3.3 V; unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. Max. Units IPOA -7.5 - 7.5 A IR -14 - 14 A - 3.0 - mV X6BB CHARACTERISTICS Optimized Accuracy Range1 Linear Sensing Range Noise2 VNOISE(rms) TA = 25C, Sens = 100 mV/A, Cf = 0, CLOAD = 4.7 nF, RLOAD open Sensitivity3 Sens Electrical Offset Voltage Variation Relative to VOUT(QBI)4 VOE Total Output Error5 ETOT IP = 6.5 A, TA = 25C - 100 - mV/A IP = 6.5 A, TA = 25C to 125C - 100 - mV/A IP = 6.5 A, TA = - 40C to 25C - 101 - mV/A IP = 0 A, TA = 25C - 11 - mV IP = 0 A, TA = 25C to 125C - 11 - mV IP = 0 A, TA = - 40C to 25C - 35 - mV Over full scale of IPOA, IP applied for 5 ms, TA = 25C to 125C - 2.2 - % Over full scale of IPOA, IP applied for 5 ms, TA = - 40C to 25C - 6 - % 1Although the device is accurate over the entire linear range, the device is programmed for maximum accuracy over the range defined by IPOA . The reason for this is that in many applications, such as motor control, the start-up current of the motor is approximately three times higher than the running current. 2V pk-pk noise (6 sigma noise) is equal to 6 x VNOISE(rms). Lower noise levels than this can be achieved by using Cf for applications requiring narrower bandwidth. See Characteristic Performance page for graphs of noise versus Cf and bandwidth versus Cf. 3This parameter can drift by as much as 2.4% over the lifetime of this product. 4This parameter can drift by as much as 13 mV over the lifetime of this product. 5This parameter can drift by as much as 2.5% over the lifetime of this product. PERFORMANCE CHARACTERISTICS, TA Range K, valid at TA = - 40C to 125C, VCC = 3.3 V; unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. Max. Units IPOA -12.5 - 12.5 A IR -37.5 - 37.5 A X12CB CHARACTERISTICS Optimized Accuracy Range1 Linear Sensing Range Noise2 Sensitivity3 VNOISE(rms) TA = 25C, Sens = 37 mV/A, Cf = 0, CLOAD = 4.7 nF, RLOAD open Sens Electrical Offset Voltage Variation Relative to VOUT(QBI)4 VOE Total Output Error5 ETOT - 1.0 - mV IP = 12.5 A, TA = 25C - 37.1 - mV/A IP = 12.5 A, TA = 25C to 125C - 37.0 - mV/A IP = 12.5 A, TA = - 40C to 25C - 37.7 - mV/A IP = 0 A, TA = 25C - 6 - mV IP = 0 A, TA = 25C to 125C - 11 - mV IP = 0 A, TA = - 40C to 25C - 21 - mV Over full scale of IPOA, IP applied for 5 ms, TA = 25C to 125C - 2.7 - % Over full scale of IPOA, IP applied for 5 ms, TA = - 40C to 25C - 6.5 - % 1Although the device is accurate over the entire linear range, the device is programmed for maximum accuracy over the range defined by IPOA . The reason for this is that in many applications, such as motor control, the start-up current of the motor is approximately three times higher than the running current. 2V pk-pk noise (6 sigma noise) is equal to 6 x VNOISE(rms). Lower noise levels than this can be achieved by using Cf for applications requiring narrower bandwidth. See Characteristic Performance page for graphs of noise versus Cf and bandwidth versus Cf. 3This parameter can drift by as much as 2.4% over the lifetime of this product. 4This parameter can drift by as much as 13 mV over the lifetime of this product. 5This parameter can drift by as much as 2.5% over the lifetime of this product. Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 6 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection ACS716 PERFORMANCE CHARACTERISTICS, TA Range K, valid at TA = - 40C to 125C, VCC = 3.3 V; unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. Max. Units IPOA -25 - 25 A IR -50 - 50 A - 0.5 - mV X25CB CHARACTERISTICS Optimized Accuracy Range1 Linear Sensing Range Noise2 Sensitivity3 VNOISE(rms) TA = 25C, Sens = 18.5 mV/A, Cf = 0, CLOAD = 4.7 nF, RLOAD open Sens Electrical Offset Voltage Variation Relative to VOUT(QBI)4 VOE Total Output Error5 ETOT IP = 25 A, TA = 25C - 18.6 - mV/A IP = 25 A, TA = 25C to 125C - 18.5 - mV/A IP = 25 A, TA = - 40C to 25C - 18.9 - mV/A IP = 0 A, TA = 25C - 5 - mV IP = 0 A, TA = 25C to 125C - 13 - mV IP = 0 A, TA = - 40C to 25C - 18 - mV Over full scale of IPOA, IP applied for 5 ms, TA = 25C to 125C - 2.9 - % Over full scale of IPOA, IP applied for 5 ms, TA = - 40C to 25C - 5.2 - % 1Although the device is accurate over the entire linear range, the device is programmed for maximum accuracy over the range defined by IPOA . The reason for this is that in many applications, such as motor control, the start-up current of the motor is approximately three times higher than the running current. 2V pk-pk noise (6 sigma noise) is equal to 6 x VNOISE(rms). Lower noise levels than this can be achieved by using Cf for applications requiring narrower bandwidth. See Characteristic Performance page for graphs of noise versus Cf and bandwidth versus Cf. 3This parameter can drift by as much as 2.4% over the lifetime of this product. 4This parameter can drift by as much as 13 mV over the lifetime of this product. 5This parameter can drift by as much as 2.5% over the lifetime of this product. Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 7 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection ACS716 Characteristic Performance ACS716 Bandwidth versus External Capacitor Value, CF Capacitor connected between FILTER pin and GND 1000 Bandwidth (kHz) 100 10 1 0.1 0.01 0.1 1 10 100 1000 Capacitance (nF) Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 8 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection ACS716 Characteristic Performance Data Data taken using the ACS716-6BB Accuracy Data Electrical Offset Voltage versus Ambient Temperature Sensitivity versus Ambient Temperature 50 110.0 40 107.5 30 105.0 Sens (mV/A) VOE (mV) 20 10 0 -10 -20 100.0 97.5 95.0 -30 92.5 -40 -50 -50 102.5 90.0 -25 0 25 50 75 100 125 150 -50 -25 0 25 TA (C) 100.75 0.2 100.50 ESYM (%) 0.3 0.1 0 -0.1 99.75 99.50 99.25 50 150 100.00 -0.3 25 125 100.25 -0.2 0 100 Symmetry versus Ambient Temperature 101.00 75 100 125 99.00 -50 150 -25 0 25 TA (C) 50 75 100 125 150 TA (C) Total Output Error versus Ambient Temperature 8.0 6.0 4.0 2.0 ETOT (%) ELIN (%) Nonlinearity versus Ambient Temperature -25 75 TA (C) 0.4 -0.4 -50 50 0 -2.0 -4.0 -6.0 -8.0 -50 -25 0 25 50 75 100 125 150 TA (C) Typical Maximum Limit Mean Typical Minimum Limit Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 9 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection ACS716 Characteristic Performance Data Data taken using the ACS716-12CB Accuracy Data Electrical Offset Voltage versus Ambient Temperature Sensitivity versus Ambient Temperature 50 40 30 Sens (mV/A) VOE (mV) 20 10 0 -10 -20 -30 -40 -50 -50 -25 0 25 50 75 100 125 40.0 39.5 39.0 38.5 38.0 37.5 37.0 36.5 36.0 35.5 150 -50 -25 0 25 TA (C) 100.75 0.2 100.50 ESYM (%) 0.3 0.1 0 -0.1 99.75 99.50 99.25 50 150 100.00 -0.3 25 125 100.25 -0.2 0 100 Symmetry versus Ambient Temperature 101.00 75 100 125 99.00 -50 150 -25 0 25 TA (C) 50 75 100 125 150 TA (C) Total Output Error versus Ambient Temperature 8.0 6.0 4.0 2.0 ETOT (%) ELIN (%) Nonlinearity versus Ambient Temperature -25 75 TA (C) 0.4 -0.4 -50 50 0 -2.0 -4.0 -6.0 -8.0 -50 -25 0 25 50 75 100 125 150 TA (C) Typical Maximum Limit Mean Typical Minimum Limit Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 10 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection ACS716 Characteristic Performance Data Data taken using the ACS716-25CB Accuracy Data Electrical Offset Voltage versus Ambient Temperature Sensitivity versus Ambient Temperature 20.5 50 40 20.0 30 Sens (mV/A) VOE (mV) 20 10 0 -10 -20 19.5 19.0 18.5 18.0 -30 17.5 -40 -50 -50 -25 0 25 50 75 100 125 17.0 150 -50 -25 0 25 TA (C) 100.75 0.2 100.50 ESYM (%) 0.3 0.1 0 -0.1 99.75 99.50 99.25 50 150 100.00 -0.3 25 125 100.25 -0.2 0 100 Symmetry versus Ambient Temperature 101.00 75 100 125 99.00 -50 150 -25 0 25 TA (C) 50 75 100 125 150 TA (C) Total Output Error versus Ambient Temperature 8.0 6.0 4.0 2.0 ETOT (%) ELIN (%) Nonlinearity versus Ambient Temperature -25 75 TA (C) 0.4 -0.4 -50 50 0 -2.0 -4.0 -6.0 -8.0 -50 -25 0 25 50 75 100 125 150 TA (C) Typical Maximum Limit Mean Typical Minimum Limit Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 11 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection ACS716 Setting Overcurrent Fault Switchpoint The VOC needed for setting the overcurrent fault switchpoint can be calculated as follows: VOC = Sens x | IOC | , where VOC is in mV, Sens in mV/A, and IOC (overcurrent fault switchpoint) in A. | Ioc | is the overcurrent fault switchpoint for a bidirectional (AC) current, which means a bi-directional sensor will have two symmetrical overcurrent fault switchpoints, +IOC and -IOC . See the following graph for IOC and VOC ranges. IOC versus VOC IOC 0.4 VCC / Sens Not Valid Range Valid Range 0.25 VCC / Sens 0 0. 25 VCC 0. 4 VCC VOC - 0.25 VCC / Sens - 0.4 VCC / Sens Example: For ACS716KLATR-6BB-T, if required overcurrent fault switchpoint is 10 A, and VCC = 3.3 V, then the required VOC can be calculated as follows: VOC = Sens x IOC = 100 x 10 = 1000 (mV) Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 12 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection ACS716 Functional Description Overcurrent Fault Operation The primary concern with high-speed fault detection is that noise may cause false tripping. Various applications have or need to be able to ignore certain faults that are due to switching noise or other parasitic phenomena, which are application dependant. The problem with simply trying to filter out this noise in the main signal path is that in high-speed applications, with asymmetric noise, the act of filtering introduces an error into the measurement. To get around this issue, and allow the user to prevent the fault signal from being latched by noise, a circuit was designed to T pin voltage based on the value of the capacitor slew the FAUL from that pin to ground. Once the voltage on the pin falls below 2 V, as established by an internal reference, the fault output is latched and pulled to ground quickly with an internal N-channel MOSFET. Fault Walk-through The following walk-through references various sections and attributes in the figure below. This figure shows different fault set/reset scenarios and how they relate to the voltages on T pin, FAULT_EN pin, and the internal Overcurrent the FAUL (OC) Fault node, which is invisible to the customer. 1. Because the device is enabled (FAULT_EN is high for a minimum period of time, the Fault Enable Delay, tFED , 15 s T typical) and there is an OC fault condition, the device FAUL pin starts discharging. VCC 1 4. The slope, and thus the delay to latch the fault is controlled by T pin to ground. Durthe capacitor, COC, placed on the FAUL T pin is between ing this portion of the fault (when the FAUL VCC and 2 V), there is a 3 mA constant current sink, which discharges COC. The length of the fault delay, t, is equal to: COC ( VCC - 2 V ) (1) 3 mA where VCC is the device power supply voltage in volts, t is in seconds and COC is in Farads. This formula is valid for RPU equal to or greater than 330 k. For lower-value resistors, the current flowing through the RPU resistor during a fault event, IPU , will be larger. Therefore, the current discharging the capacitor would be 3 mA - IPU and equation 1 may not be valid. t= 1 tFED 4 FAULT (Output) 2V T pin voltage reaches approximately 2 V, the 2. When the FAUL T fault is latched, and an internal NMOS device pulls the FAUL pin voltage to approximately 0 V. The rate at which the FAULT pin slews downward (see [4] in the figure) is dependent on the T pin. external capacitor, COC, on the FAUL T 3. When the FAULT_EN pin is brought low, the FAUL pin starts resetting if no OC fault condition exists, and if FAULT_EN is low for a time period greater than tOCH . The internal NMOS pull-down turns off and an internal PMOS pullup turns on (see [7] if the OC fault condition still exists). 6 1 6 4 8 4 5 2 4 2 6 2 7 3 0V Time FAULT_EN (Input) OC Fault Condition (Active High) Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 13 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection T pin did not reach the 2 V latch point before the 5. The FAUL OC fault condition cleared. Because of this, the fixed 3 mA current sink turns off, and the internal PMOS pull-up turns on T pin. to recharge COC through the FAUL 6. This curve shows VCC charging external capacitor COC through the internal PMOS pull-up. The slope is determined by COC. 7. When the FAULT_EN pin is brought low, if the fault condition T pin will be pulled low by the still exists, the latched FAUL internal 3mA current source. When fault condition is removed then the Fault pin charges as shown in step 6. 8. At this point there is a fault condition, and the part is enabled T pin can charge to VCC. This shortens the before the FAUL user-set delay, so the fault is latched earlier. The new delay time can be calculated by equation 1, after substituting the T pin for VCC. voltage seen on the FAUL 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 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 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. Regulator Clock/Logic Hall Element Amp Sample and Hold ACS716 Low-Pass Filter Concept of Chopper Stabilization Technique Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 14 ACS716 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection Definitions of Accuracy Characteristics 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 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. 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 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: { [ 100 1- VIOUT_full-scale amperes - VIOUT(Q) 2 (VIOUT_1/2 full-scale amperes - VIOUT(Q) ) [{ Accuracy is divided into four areas: 0 A at 25C. Accuracy of sensing zero current flow at 25C, without the effects of temperature. 0 A over temperature. Accuracy of sensing zero current flow including temperature effects. Full-scale current at 25C. Accuracy of sensing the full-scale current at 25C, without the effects of temperature. Full-scale current over temperature. Accuracy of sensing fullscale current flow including temperature effects. Ratiometry. The ratiometric feature means that its 0 A output, VIOUT(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, VIOUT(Q)RAT (%). 100 VCC / 3.3 (V) The ratiometric change in sensitivity, SensRAT (%), is defined as: where VIOUT_full-scale amperes = the output voltage (V) when the sensed current approximates full-scale IP . 100 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: 100 VIOUT(Q)VCC / VIOUT(Q)3.3V SensVCC / Sens3.3V VCC / 3.3 (V) Output Voltage versus Sensed Current Accuracy at 0 A and at Full-Scale Current Increasing VIOUT(V) Accuracy Over $Temp erature VIOUT_+ full-scale amperes - VIOUT(Q) VIOUT(Q) - VIOUT_-full-scale amperes Accuracy 25C Only Quiescent output voltage (VIOUT(Q)). The output of the sensor when the primary current is zero. For a unipolar supply voltage, it nominally remains at 0.5xVCC. For example, in the case of a bidirectional output device, VCC = 3.3 V translates into VIOUT(Q) = 1.65 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 voltage 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 ouput error. The accuracy is illustrated graphically in the output voltage versus current chart at right. Note that error is directly measured during final test at Allegro. Average VIOUT Accuracy Over $Temp erature Accuracy 25C Only IP(min) -IP (A) +IP (A) Full Scale IP(max) 0A Accuracy 25C Only Accuracy Over $Temp erature Decreasing VIOUT(V) Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 15 ACS716 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection Definitions of Dynamic Response Characteristics I (%) Propagation delay (tPROP). The time required for the sensor output to reflect a change in the primary current signal. Propagation 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 90 Transducer Output 0 Propagation Time, tPROP I (%) 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. Primary Current 90 Transducer Output 0 Response Time, tRESPONSE I (%) 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 (-3 dB) = 0.35 / tr. Both tr and tRESPONSE are detrimentally affected by eddy current losses observed in the conductive IC ground plane. t t Primary Current 90 Transducer Output 10 0 Rise Time, tr t Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 16 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection ACS716 Package LA, 16-pin SOICW 10.30 0.20 8 0 16 0.33 0.20 7.50 0.10 0.65 16 1.27 2.25 10.30 0.33 9.50 A 1.40 REF 1 2 1.27 0.40 Branded Face 16X SEATING PLANE 0.10 C 0.51 0.31 1.27 BSC 2 0.25 BSC C SEATING PLANE GAUGE PLANE C PCB Layout Reference View 2.65 MAX 0.30 0.10 For Reference Only; not for tooling use (reference MS-013AA) Dimensions in millimeters 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 B Branding scale and appearance at supplier discretion C 1 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 NNNNNNNNNNN TTT-TTT LLLLLLLLL 1 B Standard Branding Reference View N = Device part number T = Temperature range, package - amperage L = Lot number Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 17 ACS716 120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection Revision History Revision Revision Date Rev. 2 April 12, 2012 Description of Revision Update VCCN Copyright (c)2011-2012, Allegro MicroSystems, Inc. Allegro MicroSystems, Inc. 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, Inc. 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, visit our website: www.allegromicro.com Allegro MicroSystems, Inc. 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 18