ACS37800KMACTR-090B3-I2C

ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging DESCRIPTION FEATURES AND BENEFITS • Accurate power monitoring for AC and DC applications • UL 60950-1 (ed. 2) and UL 62368-1 (ed. 1) certified for reinforced isolation up to 517 VRMS in a single package • Accurate measurements of active, reactive, and apparent power, as well as power factor • Separate RMS and instantaneous measurements for both voltage and current channels • Two programmable averaging blocks • 0.85 mΩ primary conductor resistance for low power loss and high inrush current withstand capability • Compatible with floating and non-floating GND • Dedicated voltage or current zero crossing pin • Fast, user-programmable overcurrent fault pin (5 µs typ.) • User-programmable undervoltage and overvoltage RMS thresholds • 1 kHz bandwidth • Current sensing range up to 90 A • Options for I2C or SPI digital interface protocols PACKAGE 16-pin SOICW (suffix MA) 1 MΩ 1 MΩ 1 MΩ 1 MΩ 1 2 3 4 5 6 7 CB Certificate Number: US-32210-M1-UL US-36315-UL The ACS37800 power monitoring IC offers key power measurement parameters that can easily be accessed through its SPI or I2C digital protocol interfaces. Dedicated and configurable I/O pins for voltage/current zero crossing, undervoltage and overvoltage reporting, and fast overcurrent fault detection are available in I2C mode. User configuration of the IC is available through on-chip EEPROM. REINFORCED ISOLATION N (L) IP Allegro’s Hall-effect-based, galvanically isolated current sensing technology achieves reinforced isolation ratings (4800 VRMS) in a small PCB footprint. These features enable isolated current sensing without expensive Rogowski coils, oversized current transformers, isolated operational amplifiers, or the power loss of shunt resistors. The ACS37800 is provided in a small low-profile surface mount SOIC16 wide-body package, is lead (Pb) free, and is fully calibrated prior to shipment from the Allegro factory. Customer calibration can further increase accuracy in application. Not to scale L (N) The Allegro ACS37800 power monitoring IC greatly simplifies the addition of power monitoring to many AC or DC powered systems. The sensor may be powered from the same supply as the system’s MCU, eliminating the need for multiple power supplies. The device’s construction includes a copper conduction path that generates a magnetic field proportional to applied current. The magnetic field is sensed differentially to reject errors introduced by common mode fields. 8 MCU RSENSE GND IP+ ACS37800 VINP IP+ VINN IP+ GND IP+ VCC IP- SDA / MISO IP- SCL / SCLK IP- DIO_0 / MOSI IP- DIO_1 / CS Single Output Isolated Power Supply (Flyback, etc.) 16 VCC I2C Only 15 14 RPULLUP To User 13 12 RPULLUP 11 10 9 Linear Regulator Figure 1: Typical Application ACS37800-DS, Rev. 2 MCO-0001004 February 24, 2021 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging SELECTION GUIDE Part Number VCC(typ) (V) IPR (A) ACS37800KMACTR-015B5-SPI 5 ±15 ACS37800KMACTR-030B3-SPI 3.3 ±30 ACS37800KMACTR-030B3-I2C 3.3 ±30 ACS37800KMACTR-090B3-I2C 3.3 ±90 [1] Contact Allegro Communication Protocol TA (°C) Packing [1] –40 to 125 Tape and reel, 1000 pieces per reel, 3000 pieces per box SPI I2C for additional packing options. ACS 37800 K MAC TR - 015 B 5 - SPI Communication Protocol Supply Voltage: 5 – VCC = 5 V 3 – VCC = 3.3 V Output Directionality: B – Bidirectional Current Sensing Range (A) Packing Designator Package Designator Operating Temperature Range 5 Digit Part Number Allegro Current Sensor Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 2 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging ABSOLUTE MAXIMUM RATINGS Characteristic Symbol Notes Rating Units Supply Voltage VCC 6.5 V Reverse Supply Voltage VRCC –0.5 V Input Voltage VINP, VINN VCC + 0.5 V Reverse Input Voltage VRNP, VRNN –0.5 V 6 V –0.5 V Digital I/O Voltage VDIO Reverse Digital I/O Voltage VRDIO Maximum Continuous Current ICMAX TA = 25°C 60 A TA Range K –40 to 125 °C Operating Ambient Temperature SPI, I2C, and general purpose I/O Junction Temperature TJ(max) 165 °C Storage Temperature Tstg –65 to 170 °C ISOLATION CHARACTERISTICS Characteristic Symbol Dielectric Strength Test Voltage VISO Notes Agency type-tested for 60 seconds per UL 60950-1 (edition 2) and UL 62368-1 (edition 1); Production tested at 3000 VRMS for 1 second, in accordance with UL 60950-1 (edition 2) and UL 62368-1 (edition 1) Working Voltage for Basic Isolation VWVBI Maximum approved working voltage for basic (single) isolation according to UL 60950-1 (edition 2) and UL 62368-1 (edition 1) Working Voltage for Reinforced Isolation VWVRI Maximum approved working voltage for reinforced isolation according to UL 60950-1 (edition 2) and UL 62368-1 (edition 1) Clearance Rating Unit 4800 VRMS 1480 VPK or VDC 1047 VRMS 730 VPK or VDC 517 VRMS Dcl Minimum distance through air from IP leads to signal leads 7.5 mm Creepage Dcr Minimum distance along package body from IP leads to signal leads 7.9 mm Distance Through Insulation DTI Minimum internal distance through insulation 90 μm Comparative Tracking Index CTI Material Group II 400 to 599 V ESD RATINGS Value Unit Human Body Model Characteristic Symbol VHBM Per JEDEC JS-001 Notes ±5 kV Charged Device Model VCDM Per JEDEC JS-002 ±1 kV THERMAL CHARACTERISTICS Characteristic Symbol Test Conditions [1] Value Units Package Thermal Resistance (Junction to Ambient) RθJA Mounted on the Allegro ASEK37800 evaluation board with 750 of 4 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. 23 °C/W Package Thermal Resistance (Junction to Lead) RθJL Mounted on the Allegro ACS37800 evaluation board. 5 °C/W [1] mm2 Refer to the Thermal Performance section below. Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 3 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging ACS37800 FUNCTIONAL BLOCK DIAGRAM VCC DIGITAL SYSTEM Bandgap Reference Temperature Compensation Logic Temperature Sensor To All Subcircuits VINP ADC VINN ADC IP+ SCL / SCLK DIO_0 / MOSI EEPROM + Charge Pump V I SDA / MISO I2C/SPI Communication Metrology Engine DIO_1 / CS Fault Logic Hall Sensor Array GND IP– Figure 2: Functional Block Diagram PINOUT DIAGRAM AND TERMINAL LIST Terminal List Table IP+ 1 16 VINP IP+ 2 15 VINN IP+ 3 14 GND IP+ 4 13 VCC IP- 5 12 SDA / MISO IP- 6 11 SCL / SCLK IP- 7 10 DIO_0 / MOSI IP- 8 9 Pinout Diagram DIO_1 / CS Description Number Name 1, 2, 3, 4 IP+ Terminals for current being sensed; fused internally 5, 6, 7, 8 IP- Terminals for current being sensed; fused internally 9 DIO_1 / CS Digital I/O 1 10 DIO_0 / MOSI Digital I/O 0 MOSI 11 SCL  / SCLK SCL SCLK 12 SDA   / MISO SDA MISO 13 VCC Device power supply terminal 14 GND Device ground terminal 15 VINN Negative input voltage (always connect to GND) 16 VINP Positive input voltage I2C SPI Chip Select (CS) Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 4 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging Table of Contents Features and Benefits............................................................ 1 Description........................................................................... 1 Package.............................................................................. 1 Typical Application................................................................. 1 Selection Guide.................................................................... 2 Absolute Maximum Ratings.................................................... 3 Isolation Characteristics......................................................... 3 ESD Ratings......................................................................... 3 Thermal Characteristics......................................................... 3 Functional Block Diagram...................................................... 4 Pinout Diagram and Terminal List............................................ 4 Electrical Characteristics........................................................ 6 15B5 Performance Characteristics.......................................... 8 30B3 Performance Characteristics.......................................... 9 90B3 Performance Characteristics........................................ 10 I2C Operating Characteristics................................................11 SPI Operating Characteristics............................................... 12 Theory of Operation............................................................ 13 Introduction..................................................................... 13 Voltage and Current Measurements................................... 13 Overcurrent Measurement Path......................................... 13 Trim Methods.................................................................. 13 Power Calculations.......................................................... 14 Operational Block Diagram................................................... 15 Configurable Settings....................................................... 16 Configuring the DIO Pins (I2C Devices) ............................. 16 Configuring the Device for AC Applications............................. 19 Device EEPROM Settings................................................. 19 Voltage Measurement....................................................... 19 Current Measurement....................................................... 20 Configuring the Device for DC Applications............................ 21 Device EEPROM Settings................................................. 21 Voltage Measurement....................................................... 21 Current Measurement....................................................... 21 RMS and Power Accuracy vs. Operation Point........................ 21 RMS and Power Output Error vs. Applied Input.................... 21 15B5 IRMS and Power Error ............................................ 22 30B3 IRMS and Power Error ............................................ 22 90B3 IRMS and Power Error ............................................ 22 Digital Communication......................................................... 23 Communication Interfaces................................................. 23 SPI................................................................................. 23 Registers and EEPROM................................................... 23 EEPROM Error Checking and Correction (ECC).................. 25 I2C Slave Addressing........................................................ 25 EEPROM/Shadow Memory Map........................................... 26 Register Details – EEPROM.............................................. 27 Volatile Memory Map........................................................ 32 Register Details – Volatile................................................. 33 Application Information........................................................ 38 Thermal Rise vs. Primary Current...................................... 38 ASEK37800 Evaluation Board Layout................................. 38 Recommended PCB Layout................................................. 39 Package Outline Drawing..................................................... 40 Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 5 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging COMMON ELECTRICAL CHARACTERISTICS [1]: Valid through the full range of TA and VCC  = VCC(typ), unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. Max. Unit 5 V variant 4.5 5 5.5 V 3.3 V variant 2.97 3.3 3.63 V – 12 15 mA 0.1 – – µF – 90 – µs –250 – 250 mV 35 – 300 Hz ELECTRICAL CHARACTERISTICS Supply Voltage Supply Current Supply Bypass Capacitor Power-On Time VCC ICC CBYPASS VCC(min) ≤ VCC ≤ VCC(max), no load on output pins VCC to GND recommended tPO VOLTAGE INPUT BUFFER Differential Input Range ΔVINR ΔVIN = VINP – VINN(GND) Dynamic Input Frequency fdyn_in bypass_n_en = 0 VOLTAGE CHANNEL ADC Sample Frequency fS_V – 32 – kHz Number of Bits ADCV_B – 16 – bits ADC Fullscale ADCV_FS ΔVIN = ±250 mV, VINN= GND –27500 – 27500 codes Sens(V) ΔVINR(min) < ΔVIN < ΔVINR(max) – 110 – LSB / mV PSEV_O Ratio of change on VCC to change in offset at DC, 100% ±10% VCC(typ) –7 – 7 codes / %VCC PSEV_S Ratio of change on VCC to change in sensitivity at DC, 100% ±10% VCC(typ) –0.1 – 0.1 % / %VCC PSRRV_O Ratio of change on VCC to change in offset, 10 Hz to 10 kHz, 10% VCC(pk-pk) 60 70 – dB PSRRV_S Ratio of change on VCC to change in sensitivity, 10 Hz to 10 kHz, 10% VCC(pk-pk) 60 75 – dB – 1 – kHz – ±0.3 – mV – ±0.2 – % kHz Sensitivity Voltage Channel Power Supply Error Voltage Channel Power Supply Rejection Ratio VOLTAGE CHANNEL Internal Bandwidth BW RMS Noise NV Linearity Error Input referred ELIN_V CURRENT CHANNEL Sample Frequency fS_C – 32 – Number of Bits ADCI_B – 16 – bits ADC Fullscale ADCI_FS IP = IPR(min) or IPR(max) –27500 – 27500 codes PSEI_O Ratio of change on VCC to change in offset at DC, 100% ±10% VCC(typ) –60 – 60 codes / %VCC PSEI_S Ratio of change on VCC to change in sensitivity at DC, 100% ±10% VCC(typ) –0.3 – 0.3 % / %VCC PSRRI_O Ratio of change on VCC to change in offset, 10 Hz to 10 kHz, 10% VCC(pk-pk) 60 65 – dB PSRRI_S Ratio of change on VCC to change in sensitivity, 10 Hz to 10 kHz, 10% VCC(pk-pk) 20 40 – dB – 1 – kHz – 0.85 – mΩ Current Channel Power Supply Error Current Channel Power Supply Rejection Ratio Internal Bandwidth BW Primary Conductor Resistance RIP TA = 25°C Continued on next page... Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 6 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging COMMON ELECTRICAL CHARACTERISTICS [1] (continued): Valid through the full range of TA and VCC  = VCC(typ), unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. Max. Unit CURRENT CHANNEL (continued) RMS Noise Linearity Error NI Input referred ELIN_I – ±0.1 – A – ±1.5 – % – 5 – μs – 200 – kHz OVERCURRENT FAULT CHARACTERISTICS Fault Response Time tRF Internal Bandwidth BW Fault Hysteresis [2] Fault Range Time from IP rising above IFAULT until VFAULT < VFAULT(max) for a current step from 0 to 1.2 × IFAULT; 10 kΩ and 100 pF from DIO_1 to ground; fltdly = 0 IHYST IFAULT Set using fault field in EEPROM – 0.06 × FS – A 0.65 × FS – 2.00 × FS A – 250 – µs VOLTAGE ZERO CROSSING Voltage Zero-Crossing Delay td DIO PINS DIO Output High Level VOH(DIO) VCC = 3.3 V 3 – – V DIO Output Low Level VOL(DIO) VCC = 3.3 V – – 0.3 V DIO Input Voltage for Address Selection 0 VADD0 VCC = 3.3 V – 0 – V DIO Input Voltage for Address Selection 1 VADD1 VCC = 3.3 V – 1.1 – V DIO Input Voltage for Address Selection 2 VADD2 VCC = 3.3 V – 2.2 – V DIO Input Voltage for Address Selection 3 VADD3 VCC = 3.3 V – 3.3 – V [1] Device may be operated at higher primary current levels (IP), ambient temperatures (TA), and internal leadframe temperatures, provided that the maximum junction temperature (TJ(max)) is not exceeded. IP goes above IFAULT, tripping the internal fault comparator, IP must go below IFAULT – IHYST before the internal fault comparator will reset. [2] After Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 7 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging ACS37800KMAC-015B5 PERFORMANCE CHARACTERISTICS: Valid through the full operating temperature range, TA = –40°C to 125°C, CBYPASS = 0.1 µF, and VCC = 5 V, unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. [1] Max. Unit – 5 – V –15 – 15 A – 1833.3 – LSB/A GENERAL CHARACTERISTICS Nominal Supply Voltage VCC(typ) NOMINAL PERFORMANCE – FACTORY CURRENT CHANNEL Current Sensing Range Sensitivity IPR Sens(I) IPR(min) < IP < IPR(max) NOMINAL PERFORMANCE – INPUT REFERRED FACTORY POWER (POWER SEEN BY THE DEVICE) [2] Active Power Sensitivity SensPd_act – 6.15 – LSB/mW Imaginary Power Sensitivity SensPd_img – 12.31 – LSB/mVAR Apparent Power Sensitivity SensPd_app – 12.31 – LSB/mVA Measured at IP = IPR(max), TA = 25°C to 125°C – ±1.1 – % Measured at IP = IPR(max), TA = –40°C to 25°C – ±1.5 – % IP = 0 A, TA = 25°C to 125°C – ±720 – LSB IP = 0 A, TA = –40°C to 25°C – ±780 – LSB Measured at IP = IPR(max), TA = 25°C to 125°C – ±2.1 – % Measured at IP = IPR(max), TA = –40°C to 25°C – ±2.7 – % Measured at ΔVIN = ΔVINR(max), TA = 25°C to 125°C – ±1.2 – % Measured at ΔVIN = ΔVINR(max), TA = –40°C to 25°C – ±1.2 – % ΔVIN = 0 mV, TA = 25°C to 125°C – ±55 – LSB ΔVIN = 0 mV, TA = –40°C to 25°C – ±55 – LSB Measured at ΔVIN = ΔVINR(max), TA = 25°C to 125°C – ±1.4 – % Measured at ΔVIN = ΔVINR(max), TA = –40°C to 25°C – ±1.4 – % IP = IPR(max), measured at ΔVIN = ΔVINR(max), TA = 25°C to 125°C – ±2.1 – % IP = IPR(max), measured at ΔVIN = ΔVINR(max), TA = –40°C to 25°C – ±3 – % TOTAL OUTPUT ERROR COMPONENTS [3] – CURRENT CHANNEL Sensitivity Error Offset Error Total Output Error ESENS(I) EO(I) ETOT(I) TOTAL OUTPUT ERROR COMPONENTS [3] – VOLTAGE CHANNEL Sensitivity Error Offset Error Total Output Error ESENS(V) EO(V) ETOT(V) ACCURACY PERFORMANCE – ACTIVE POWER Total Output Error ETOT(P) Typical values are mean ±3 sigma. sensitivity characteristics are referred to the inputs seen by the device, i.e. the voltage channel resistor divider must be accounted to determine the system sensitivies. [3] E TOT = ESENS + 100 x VOE/(Sens x IP) [1] [2] These Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 8 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging ACS37800KMAC-030B3 PERFORMANCE CHARACTERISTICS: Valid through the full operating temperature range, TA = –40°C to 125°C, CBYPASS = 0.1 µF, and VCC = 3.3 V, unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. [1] Max. Unit – 3.3 – V –30 – 30 A – 916.7 – LSB/A GENERAL CHARACTERISTICS Nominal Supply Voltage VCC(typ) NOMINAL PERFORMANCE – CURRENT CHANNEL Current Sensing Range Sensitivity IPR Sens(I) IPR(min) < IP < IPR(max) NOMINAL PERFORMANCE – INPUT REFERRED FACTORY POWER (POWER SEEN BY THE DEVICE) [2] Active Power Sensitivity SensPd_act – 3.08 – LSB/mW Imaginary Power Sensitivity SensPd_img – 6.15 – LSB/mVAR Apparent Power Sensitivity SensPd_app – 6.15 – LSB/mVA TOTAL OUTPUT ERROR COMPONENTS [3] – CURRENT CHANNEL Sensitivity Error Offset Error Total Output Error ESENS(I) EO(I) ETOT(I) Measured at IP = IPR(max), TA = 25°C to 125°C – ±1 – % Measured at IP = IPR(max), TA = –40°C to 25°C – ±1.5 – % IP = 0 A, TA = 25°C to 125°C – ±510 – LSB IP = 0 A, TA = –40°C to 25°C – ±570 – LSB Measured at IP = IPR(max), TA = 25°C to 125°C – ±2 – % Measured at IP = IPR(max), TA = –40°C to 25°C – ±2.7 – % Measured at ΔVIN = ΔVINR(max), TA = 25°C to 125°C – ±0.75 – % Measured at ΔVIN = ΔVINR(max), TA = –40°C to 25°C – ±0.75 – % ΔVIN = 0 mV, TA = 25°C to 125°C – ±55 – LSB ΔVIN = 0 mV, TA = –40°C to 25°C – ±55 – LSB Measured at ΔVIN = ΔVINR(max), TA = 25°C to 125°C – ±1 – % Measured at ΔVIN = ΔVINR(max), TA = –40°C to 25°C – ±1 – % IP = IPR(max), measured at ΔVIN = ΔVINR(max), TA = 25°C to 125°C – ±2.1 – % IP = IPR(max), measured at ΔVIN = ΔVINR(max), TA = –40°C to 25°C – ±3 – % TOTAL OUTPUT ERROR COMPONENTS [3] – VOLTAGE CHANNEL Sensitivity Error Offset Error Total Output Error ESENS(V) EO(V) ETOT(V) ACCURACY PERFORMANCE – ACTIVE POWER Total Output Error ETOT(P) Typical values are mean ±3 sigma. sensitivity characteristics are referred to the inputs seen by the device, i.e. the voltage channel resistor divider must be accounted to determine the system sensitivies. [3] E TOT = ESENS + 100 x VOE/(Sens x IP) [1] [2] These Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 9 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging ACS37800KMAC-090B3 PERFORMANCE CHARACTERISTICS: Valid through the full operating temperature range, TA = –40°C to 125°C, CBYPASS = 0.1 µF, and VCC = 3.3 V, unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. [1] Max. Unit – 3.3 – V –90 – 90 A – 305.6 – LSB/A GENERAL CHARACTERISTICS Nominal Supply Voltage VCC(typ) NOMINAL PERFORMANCE – CURRENT CHANNEL Current Sensing Range Sensitivity IPR Sens(I) IPR(min) < IP < IPR(max) NOMINAL PERFORMANCE – INPUT REFERRED FACTORY POWER (POWER SEEN BY THE DEVICE) [2] Active Power Sensitivity SensPd_act – 1.03 – LSB/mW Imaginary Power Sensitivity SensPd_img – 2.05 – LSB/mVAR Apparent Power Sensitivity SensPd_app – 2.05 – LSB/mVA TOTAL OUTPUT ERROR COMPONENTS [3] – CURRENT CHANNEL Sensitivity Error Offset Error Total Output Error ESENS(I) EO(I) ETOT(I) TOTAL OUTPUT ERROR COMPONENTS Sensitivity Error Offset Error Total Output Error [3] – Measured at IP = IPR(max), TA = 25°C to 125°C – ±1 – % Measured at IP = IPR(max), TA = –40°C to 25°C – ±1.5 – % IP = 0 A, TA = 25°C to 125°C – ±180 – LSB IP = 0 A, TA = –40°C to 25°C – ±210 – LSB Measured at IP = 45 A, TA = 25°C to 125°C – ±2 – % Measured at IP = 45 A, TA = –40°C to 25°C – ±2.6 – % Measured at ΔVIN = ΔVINR(max), TA = 25°C to 125°C – ±0.75 – % Measured at ΔVIN = ΔVINR(max), TA = –40°C to 25°C – ±0.75 – % ΔVIN = 0 mV, TA = 25°C to 125°C – ±55 – LSB ΔVIN = 0 mV, TA = –40°C to 25°C – ±55 – LSB Measured at ΔVIN = ΔVINR(max), TA = 25°C to 125°C – ±1 – % Measured at ΔVIN = ΔVINR(max), TA = –40°C to 25°C – ±1 – % IP = 45 A, measured at ΔVIN = ΔVINR(max), TA = 25°C to 125°C – ±1.3 – % IP = 45 A, measured at ΔVIN = ΔVINR(max), TA = –40°C to 25°C – ±2.1 – % VOLTAGE CHANNEL ESENS(V) EO(V) ETOT(V) ACCURACY PERFORMANCE – ACTIVE POWER Total Output Error ETOT(P) Typical values are mean ±3 sigma. sensitivity characteristics are referred to the inputs seen by the device, i.e. the voltage channel resistor divider must be accounted to determine the system sensitivies. [3] E TOT = ESENS + 100 x VOE/(Sens x IP) [1] [2] These Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 10 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging ACS37800 xKMACTR-I2C OPERATING CHARACTERISTICS [1]: Valid through the full range of TA, VCC  = VCC(typ), REXT = 10 kΩ, unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. Max. Unit I2C INTERFACE CHARACTERISTICS [2] Bus Free Time Between Stop and Start tBUF 1.3 – – µs Hold Time Start Condition thdSTA 0.6 – – µs Setup Time for Repeated Start Condition tsuSTA 0.6 – – µs SCL Low Time tLOW 1.3 – – µs SCL High Time tHIGH 0.6 – – µs Data Setup Time tsuDAT 100 – – µs Data Hold Time thdDAT 0 – 900 µs Setup Time for Stop Condition tsuSTO 0.6 – – µs Logic Input Low Level (SDA, SCL pins) VIL – – 30 %VCC Logic Input High Level (SDA, SCL pins) VIH 70 Logic Input Current IIN Output Low Voltage (SDA) VOL Clock Frequency (SCL pin) fCLK Output Fall Time (SDA pin) tf I2C Pull-Up Resistance Total Capacitive Load for Each of SDA and SCL Buses [1] [2] – – %VCC Input voltage on SDA or SCL = 0 V to VCC –1 – 1 µA SDA sinking = 1.5 mA – – 0.36 V kHz – – 400 – – 250 ns REXT 2.4 10 – kΩ CB – – 20 pF REXT = 2.4 kΩ, CB = 100 pF Validated by characterization and design. These values are ratiometric to the supply voltage. I2C Interface Characteristics are ensured by design and not factory tested. tsuSTA tsuDAT thdSTA thdDAT tsuSTO tBUF SDA SCL tLOW tHIGH Figure 3: I2C Interface Timing Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 11 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging xKMATR-SPI OPERATING CHARACTERISTICS [1]: Valid through the full range of TA, VCC  = VCC(typ), unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. Max. Unit 2.8 – 3.63 V MOSI, SCLK, CS pins, VCC = 5 V 4 – 5.5 V MOSI, SCLK, CS pins – – 0.5 V MISO pin, CL = 20 pF, TA = 25°C, VCC(typ) = 3.3 V 2.8 3.3 3.8 V MISO pin, CL = 20 pF, TA = 25°C, VCC(typ) = 5 V 4 5 5.5 V – 0.3 0.5 V 0.1 – 10 MHz 5.8 – 588 kHz SPI INTERFACE CHARACTERISTICS Digital Input High Voltage VIH Digital Input Low Voltage VIL SPI Output High Voltage MOSI, SCLK, CS pins, VCC = 3.3 V VOH SPI Output Low Voltage VOL MISO pin, CL = 20 pF, TA = 25°C SPI Clock Frequency fSCLK MISO pin, CL = 20 pF SPI Frame Rate tSPI Chip Select to First SCLK Edge tCS Time from CS going low to SCLK falling edge 50 – – ns Data Output Valid Time tDAV Data output valid after SCLK falling edge – 40 – ns MOSI Setup Time tSU Input setup time before SCLK rising edge 25 – – ns MOSI Hold Time tHD Input hold time after SCLK rising edge 50 – – ns SCLK to CS Hold Time tCHD Hold SCLK high time before CS rising edge 5 – – ns Loading on digital output (MISO) pin – – 20 pF Load Capacitance [1] CL Validated by characterization and design. tCHD tCS >tCS CSN SCLK tSU tHD MOSI tDAV MISO Figure 4: SPI Timing Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 12 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging THEORY OF OPERATION Introduction current and voltage measurements are stored in the icodes and vcodes fields. The instantaneous apparent power, which is the product of icodes and vcodes, is stored in the field pinstant. The ACS37800 provides a simple solution for voltage, current, and power monitoring in 60 Hz AC and DC applications and is particularly well suited for high isolation. The voltage is measured by resistor dividing it down to fit the input range of the on-board voltage sense amplifier, as well as to add isolation. The current is measured using the integrated current loop and galvanically isolated Hall sensor. Both analog signals are then sampled using high accuracy ADCs before entering the digital system. Here, the metrology engine is used to determine frequency, calculate RMS values of current, voltage, and power, as well as provide a range of averaging and configuration options. One can choose to read out all the different information provided using SPI or I2C. When using I2C, there are also options for using some of the digital I/O pins for overcurrent or zero crossing detection. Overall, with a high degree of configurability and integrated features, the ACS37800 can fit most power monitoring applications. The following sections will help explain in more detail these features and configuration options, as well as how to best use the ACS37800 for particular applications. Overcurrent Measurement Path A separate filter on the current ADC is used to create a lower resolution but higher bandwidth sample rate measurement of the current to be used for overcurrent detection. This filter outputs a 12-bit word at a 1 MHz update rate and 200 kHz bandwidth. The overcurrent fault logic compares this auxiliary current value to the user-defined overcurrent fault threshold, defined by the field fault. It is important to note that the trim for the main 16-bit current path is also applied to the overcurrent path, such that the overcurrent fault has the same level of accuracy as the main signal path. Trim Methods The trim logic for the voltage and current channels is depicted in Figure 5 and Figure 6. Refer to the Register Details section for more information regarding trim fields. In general, each channel, voltage and current, is trimmed for gain and offset both at room and over temperature. This trim is done before the icodes and vcodes registers. The user has the ability to trim the nominal room temperature value. Voltage and Current Measurements The main signal paths for the current and voltage measurement, through the ADCs and internal filtering, have a bandwidth of 1 kHz and an update rate of 32 kHz. These “instantaneous” Gain Trim Delay Offset Trim adc_out_v Z VchanGainSel Satura�on -x ichan_del_en + + vcodes vchan_offset_code + chan_del_sel + vqvo_tc Factory Trim Figure 5: Voltage Channel Trim Flow Delay Offset Trim adc_out_i Gain Trim Z-x + Satura�on + icodes ichan_del_en qvo_fine ch an_del_sel qvo_tc + + sns_fine sns_tc Factory Trim Figure 6: Current Channel Trim Flow Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 13 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging Power Calculations POWER FACTOR VOLTAGE ZERO CROSSING The magnitude of the ratio of the real power to apparent power, calculated at the end of each cycle is: Voltage zero crossings are detected with time-based hysteresis that removes the possibility of noise causing multiple zero crossings to be reported at each true zero crossing. I RMS AND V RMS The cycle-by-cycle calculation of the root mean square of both the current and voltage channels is: IRMS = ∑ nn == N0 – 1 In2 N VRMS = ∑ nn == N0 – 1 Vn2 N where In (icodes) and Vn (vcodes) are the instantaneous measurements of current and voltage, respectively. |PF| = PACTIVE |S| LEADING OR LAGGING POWER FACTOR The current leading or lagging the voltage is communicated as a single bit, posangle. This bit represents the sign of the reactive power. The sign of the reactive power is determined by comparing the timing of the zero crossings of the current and voltage. As such, it is only meaningful in the case of a linear load. The sign of the reactive power, posangle, along with the sign of the power factor, pospf, can be used to determine whether the load is inductive or capacitive, as well as whether power is being generated or consumed. This is shown in the four-quadrant figure below (refer to Figure 7). Imaginary The RMS and power calculations of the ACS37800 are calculated over a window of N samples. By default, this window is calculated dynamically based on the zero crossings of the voltage signal. A rising voltage zero crossing triggers the start of a new window. N then increases with each 32 kHz sample until the next rising voltage zero crossing, recording the current and voltage readings at each sample. This ends the calculation window, and all RMS and power calculations are performed on the saved data. During this time, the next calculation window is started. POSPF = 0 POSANG = 0 POSPF = 1 POSANG = 1 Capacitive and Generating Inductive and Consuming Lagging Real APPARENT POWER Leading The magnitude of the complex power being measured; calculated at the end of each cycle is: |S| = IRMS × VRMS POSPF = 0 POSANG = 1 POSPF = 1 POSANG = 0 Inductive and Generating Capacitive and Consuming ACTIVE POWER ∑ nn == N0 – 1 Pn PACTIVE = N Figure 7: Four Quadrant, Power Factor Pn = In × Vn REACTIVE POWER The imaginary component of power being measured, calculated at the end of each cycle is: Q= S2 – PACTIVE2 p Ap nt e ar ,S er I =V w Po S= P2+Q2 Ф Reactive Power, Q = VI sinФ The real component of power being measured, calculated cycle by cycle is: Active Power, P = VI cosФ Figure 8: Power Triangle Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 14 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging OPERATIONAL BLOCK DIAGRAM Voltage and Current Measurement Factory Trimmed VLINE RSENSE Voltage ADC ΣRISO + RSENSE Digital Filter vcodes Channel Delay Control Temperature Compensation icodes IP+ IP– Overcurrent Fault Comparator Current ADC fault out fault RMS, and Power Calculation Voltage Zero Crossing Zero Crossing Flag vrms vcodes irms X icodes RMS and Power Calculations pinstant pospf posangle papparent pactive pimag Averaging and VRMS Flagging ovrms O/UVRMS Flag vrms uvrms 0 irms vrmsavgonesec 1 vrmsavgonemin iavgselen Averaging 0 pactive 1 irmsavgonesec irmsavgonemin pavgselen Register Voltage data Current data pactiveavgonesec pactiveavgonemin Output Operation FAULT data Power data Control Figure 9: Operational Block Diagram Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 15 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging Configurable Settings PHASE DELAY Phase delay may be introduced on either the voltage or current channel to account for known phase delay at other points in the system using the ichan_del_en and chan_ del_sel fields. ichan_ del_en determines if the voltage channel or current channel will be delayed. The chosen channel will be delayed by the configured amount in chan_del_sel, up to 5° of delay. AVERAGING CHANNEL The ACS37800 contains two averaging paths. VRMS, IRMS, and PACTIVE can be routed to these average blocks as shown in Figure 9 using iavgselen and pavgselen. AVERAGING TIME Each averaging path on the ACS37800 consists of two averaging blocks that each allow for a configurable number of averages based on the EEPROM fields rms_avg_1 and rms_avg_2. The output of the first averaging block feeds into the input of the second averaging block. The output of each block is accessible for each channel. OVERVOLTAGE AND UNDERVOLTAGE DETECTION FOR VRMS This device has programmable overvoltage and undervoltage RMS flags that will signal when the vrms is above or below the respective thresholds. The vrms is compared to the overvoltage and undervoltage RMS thresholds set by the fields overvreg and undervreg to determine a flag condition. The number of successive sample sets required to trigger either the overvoltage or undervoltage RMS flag can be set by the vevent_cycs field. When bypass_n_en = 1, it is important to define the number of samples used to calculate RMS. This can be done in the field n. The field n is the number of 32 kHz samples that are used to calculate the RMS. The minimum effective n that is used when calculating RMS is 4. If a value of less than 4 is chosen for n, then 4 is internally used. The first useable RMS calculation on start up with bypass_n_en = 1 is after 2 × n samples. Configuring the DIO Pins (I2C Devices) FLAGS TO BE ROUTED TO THE DIO PINS When the device is configured to be in I2C mode (comm_sel in EEPROM = 1), pins 9 and 10 become digital I/O pins, DIO_1 and DIO_0, respectively. The digital I/O pins are low true, meaning that a voltage below the DIO Output Low Level maximum (VOL(DIO)max) is to be interpreted as logic 1 and a voltage above DIO Output High Level minimum (VOH(DIO)min) is to be interpreted as a logic 0. The Digital I/O pins can be configured in EEPROM to represent the following functions: DIO_O dio_0_sel value (EEPROM) 0 ZC: zero crossing 1 ovrms: the VRMS overvoltage flag 2 uvrms: The VRMS undervoltage flag 3 The OR of ovrms and uvrms (if either flag is triggered, the DIO_0 pin will be asserted) ZC The overcurrent fault threshold may be set from 0.65 × IPR to 2.0 × IPR. The user sets the trip point with the field fault. The user can add a digital delay to the overcurrent fault with the field flt_dly. Up to 32 µs delay can be added to the overcurrent fault. DIO_0_Sel[0..1] OCF UVRMS OVRMS OCF_LAT dio_1_sel value (EEPROM) 0 1 OVRMS UVRMS DIO_0 / MOSI MOSI UVRMS BYPASSING THE DYNAMIC FRAMING OF THE RMS CALCULATION WINDOW By default, the ACS37800 dynamically calculates the value of N to be used in the RMS and power calculations based on the zero crossings on the voltage channel. This functionality can be disabled using the bypass_n_en field. DIO_0 OVRMS The ovrms and uvrms flags can be routed to the DIO pins when the device is used in I2C mode. See Configuring the DIO Pins. OVERCURRRENT DETECTION FOR INSTANTANEOUS CURRENT Function 2 3 Comm_Sel DIO_1DIO_1 Function DIO_1 / CS CS OCF: Overcurrent fault DIO_1_Sel[0..1] Comm_Sel uvrms: The VRMS undervoltage flag ZC DIO_0 ovrms: The VRMS overvoltage flag MOSI DIO_0 / MOSI The OR of ovrms and uvrms, and OCF_LAT [Latched Overcurrent Fault] (if any of the three flags are DIO_0_Sel[0..1] Comm_Sel triggered, the DIO_1 pin will be asserted) OCF DIO_1 UVRMS OVRMS OCF_LAT DIO_1 / CS CS DIO_1_Sel[0..1] Comm_Sel Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 16 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging ZERO CROSSING OUTPUT CONFIGURATIONS The dynamic calculation of N for the RMS and power calculations uses exclusively the voltage zero crossing, but both current and voltage zero crossing can be flagged and reported on the DIO pins. Voltage Zero Crossing (VZC) The voltage zero crossing has two basic modes of operation, pulse mode and square wave mode. Pulse Mode – VZC In pulse mode, a voltage zero crossing is reported as a short pulse. There are three available configurations to customize the voltage zero crossing pulse mode operation: rising or falling edge selection, every edge selection, and pulse width. Figure 11: zerocrossedgesel = 1, Rising Zero Crossing Rising Edge or Falling Edge Aligned Pulse Pulse Every Edge The EEPROM field zerocrossedgesel is used to select whether the zero crossing output pulses are aligned to the rising zero crossing of the voltage channel or the falling zero crossing of the voltage channel. The EEPROM field halfcycle_en is used to output a pulse at every zero crossing. Figure 12: halfcycle_en = 1, Both Rising and Falling Zero Crossings Signaled Figure 10: zerocrossedgesel = 0, Falling Zero Crossing Pulse Width Selection The EEPROM field delaycnt_sel is used to select the width of the voltage zero crossing pulse. Table 1: delaycnt_sel Range Value Units 0 32 µs 1 256 µs Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 17 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging Square Wave Mode Square wave mode can be configured using the EEPROM field squarewave_en. In square wave mode, a voltage zero crossing is reported as a square wave that changes state on each reported zero crossing. The zerocrossedgesel EEPROM field can be used to align the low to high transition of the flag with either the rising voltage zero crossing or the falling voltage zero crossing. The current zero crossing has just one basic mode of operation: pulse mode. Pulse Mode – CZC In pulse mode, a current zero crossing is reported as a short pulse. There are three available configurations to customize the current zero crossing pulse mode operation: rising or falling edge selection, every edge selection, and pulse width. Rising Edge or Falling Edge Aligned Pulse The EEPROM field zerocrossedgesel is used to select whether the zero crossing output pulses are aligned to the rising zero crossing of the current channel or the falling zero crossing of the current channel. Figure 13: zerocrossedgesel = 0, Square Wave Mode Figure 15: zerocrossedgesel = 0, Falling Zero Crossing Figure 14: zerocrossedgesel = 1, Square Wave Mode Current Zero Crossing (CZC) The current zero crossing function can be enabled using the EEPROM field zerocrosschansel. When the zero crossing flag is configured to flag zero crossings of the current path, this has no effect on the RMS and power calculations; the voltage zero crossing is still used for these calculations. Figure 16: zerocrossedgesel = 1, Rising Zero crossing Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 18 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging Pulse Every Edge The EEPROM field halfcycle_en is used to output a pulse at every zero crossing. Figure 17: halfcycle_en = 1, Both Rising and Falling Zero Crossings Signaled CONFIGURING THE DEVICE FOR AC APPLICATIONS Device EEPROM Settings For AC power monitoring applications using the ACS37800, the following device settings are recommended: DYNAMIC CALCULATION OF N Set bypass_n_en = 0 (default). This setting enables the device to dynamically calculate N based off the voltage zero crossings. See the Register Details – EEPROM section for additional details. Voltage Measurement form a resistor divider network where, 𝑉𝑉𝐼𝐼𝐼𝐼 = 𝑉𝑉𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿 ∗ RISO1 and RISO2 should be equal. A value of 1 MΩ is appropriate for many applications, but ultimately, the resistance value used needs to comply with the required isolation of the system. VINP RECOMMENDED APPLICATION CIRCUITS An important aspect to consider when designing in the ACS37800 into AC applications is the design of the voltage measurement path. Typically, a resistor divider network is employed to provide both isolation and transform the high voltage signal into the ±250 mV signal that the ACS37800 can measure. There are two basic application circuits recommended based on the isolation requirements of the system. The first, see Figure 18, is to be used when the ACS37800 GND and the neutral terminal of the voltage input are connected. RISO1, RISO2, and RSENSE 𝑅𝑅𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 𝑅𝑅𝐼𝐼𝐼𝐼𝐼𝐼1 + 𝑅𝑅𝐼𝐼𝐼𝐼𝐼𝐼2 + 𝑅𝑅𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 RISO1 1 MΩ RISO2 1 MΩ RSENSE Vin VINN Figure 18: Voltage Channel Application Circuit; Device GND is Connected to Neutral Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 19 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging 𝑉𝑉𝐼𝐼𝐼𝐼 = 𝑉𝑉𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿 ∗ 𝑅𝑅𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 𝑅𝑅𝐼𝐼𝐼𝐼𝐼𝐼1 + 𝑅𝑅𝐼𝐼𝐼𝐼𝐼𝐼2 + 𝑅𝑅𝐼𝐼𝐼𝐼𝐼𝐼3 + 𝑅𝑅𝐼𝐼𝐼𝐼𝐼𝐼4 + 𝑅𝑅𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 RISO1, RISO2, RISO3, and RISO4 should be equal and their value is determined by the isolation requirements of the system. A value of 1 MΩ is appropriate for many applications, but ultimately, the resistance value used needs to comply with the required isolation of the system. 1 MΩ RISO2 1 MΩ RSENSE If the RSENSE is not sized appropriately, this can lead to the voltage input to the ACS38700 exceeding the maximum input range, which can cause the instantaneous voltage measurement to saturate. This can lead to errors in the RMS calculations as shown in Figure 20. Input > Fullscale Output Fullscale Range RISO1 VINP Additionally, the tolerance of the all resistors should be considered when determining RSENSE. The minimum tolerance of the isolation resistors should be used along with the maximum tolerance of RSENSE. Vin Output Saturation Expected RMS Another application circuit recommendation for the voltage channel is shown in Figure 19. This is to be used in systems where the ACS37800 GND and the neutral terminal of the voltage input are to be isolated. Here, RISO3 and RISO4 are added to the resistor divider network. Output RMS ACS37800 Input Waveform Output Readpoints Absolute Output Readpoints RISO3 VINN 1 MΩ RISO4 1 MΩ Figure 19: Voltage Channel Application; Device GND is Isolated from Neutral To determine the value of RSENSE required for a particular application using either of the recommended circuits, the following equation can be used: 𝑅𝑅𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 = ∆𝑉𝑉𝐼𝐼𝐼𝐼𝐼𝐼 (𝑀𝑀𝑀𝑀𝑀𝑀) 𝑉𝑉𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿(𝑀𝑀𝑀𝑀𝑀𝑀) − ∆𝑉𝑉𝐼𝐼𝐼𝐼𝐼𝐼 (𝑀𝑀𝑀𝑀𝑀𝑀) ∗ 𝑅𝑅𝐼𝐼𝐼𝐼𝐼𝐼 Where ΔVINR(MAX) = 250 mV, VLINE(MAX) is the maximum VLINE voltage to be measured, and RISO is the sum of all of the isolation resistors. If using the overvoltage detection functionality of the ACS37800, this should be considering when determining the maximum VLINE voltage to be measured. For example, in an application when the nominal VLINE is equal to 120 VRMS and a 50% over-voltage detection is required, VLINE(MAX) is: Figure 20: Output Saturation Current Measurement For the current path, there are two current ranges to consider: the range of RMS current to be measured and the range required for overcurrent fault detection. When considering the range of RMS current to be measured, the Current Sensing Range (IPR) is not to be exceeded. This can lead to saturation, as shown in Figure 20, and lead to error in the RMS calculations. The overcurrent fault detection can exceed IPR and is defined as Fault Range Max, IFAULT(MAX). Once the current exceeds IPR, the RMS calculations will no longer be accurate. 120 VRMS × √2 × 1.5 = 255 V, where the √2 is used to approximate the peak voltage assuming a sinusoidal input. Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 20 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging ACS37800 CONFIGURING THE DEVICE FOR DC APPLICATIONS OR FOR APPLICATIONS WITH NO VOLTAGE ZERO CROSSING The follow recommendations are provided for DC applications, as well as any other applications where there is no voltage zero crossing. Possible applications include current sensing only, sensing of a rectified voltage signal, or applications where the nominal frequency on the voltage channel is greater than 300 Hz. Device EEPROM Settings For DC power monitoring applications using the ACS37800 or applications only using the current measurement capability of the ACS37800, the following device settings are recommended. FIXED SETTING OF N Set bypass_n_en = 1. This setting disables the dynamic calculation of n based off voltage zero crossings and sets n to a fixed value, which is set using EERPOM field n. See the Register Details – EEPROM section for additional details. Voltage Measurement RECOMMENDED APPLICATION CIRCUITS The recommended application circuit for the voltage channel in DC operation is the same as the AC application circuit where Device GND is connected to Neutral (refer to Figure 18). Current Measurement The same considerations for AC applications can be used for the current path for DC applications. RMS AND POWER ACCURACY VS. OPERATION POINT When using the ACS37800 to measure for RMS calculations and power monitoring, it is important to consider the error specifications of the device. For DC applications, the impact of offset and gain error on the final output is straightforward, but for RMS and power calculations, the impact of any errors, specifically offset errors, becomes dependent on the magnitude of the applied signal. Figure 21 shows an example system where the maximum measurable power is ~1.3 kW, based on the system design. The overtemperature offset performance of the ACS37800 causes an error in the measured power that is larger when the applied power is close to 0 W. The offset performance of the voltage channel is such that its contribution to this error is negligible. The current RMS measurement and the power calculations are where this error is observed. Measured Line Power (W) RMS and Power Output Error vs. Applied Input Figure 21: Line Power Applied (W) vs. Measured Line Power (W), 15B5 Device The following figures (Figure 22 through Figure 27) display the measurement error for the RMS current and active power for each available device variant. Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 21 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging ACS37800 15B5 IRMS and Power Error     ° ° °     ° ° °                           Figure 22: IRMS Error [A] vs. Applied IRMS [A]    ° ° °                  Figure 24: IRMS Error [A] vs. Applied IRMS [A] 90B3 IRMS and Power Error         ° ° °   Figure 25: Line Power Error [W] vs. Applied Line Power [W]        ° ° °                         ° ° °         Figure 23: Line Power Error [W] vs. Applied Line Power [W]      30B3 IRMS and Power Error             Figure 26: IRMS Error [A] vs. Applied IRMS [A]            Figure 27: Line Power Error [W] vs. Applied Line Power [W] Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 22 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging DIGITAL COMMUNICATION Communication Interfaces Registers and EEPROM The ACS37800 supports communication over 1 MHz I2C and 10 MHz SPI. However, the communication protocol is fixed during factory programming. The ACS37800 MISO pin continues to drive the MISO line when CS goes high. This may prevent other devices from communicating properly. It is recommended that the ACS37800 be the only device on the SPI bus if using SPI communication. WRITE ACCESS The ACS37800 supports factory and customer EEPROM space as well as volatile registers. The customer access code must be sent prior to writing these customer EEPROM spaces. In addition, the device includes a set of free space EEPROM registers that are accessible with or without writing the access code. SPI READ ACCESS All EEPROM and volatile registers may be read at any time regardless of the access code. The SPI frame consists of: • The Master writes on the MOSI line the 7-bit address of the register to be read from or written to. EEPROM • The next bit on the MOSI line is the read/write (RW) indicator. A high state indicates a Read and a low state indicates a Write. At power up, all shadow registers are loaded from EEPROM, including all configuration parameters. The shadow registers can be written to in order to change the device behavior without having to perform an EEPROM write. Any changes made in shadow memory are volatile and do not persist through a reset event. • The device sends a 32-bit response on the MISO line. The contents correspond to the previous command. • On the MOSI line, if the current command is a write, the 32 bits correspond to the Write data, and in the case of a read, the data is ignored. WRITING The Timing Diagram for an EEPROM write is shown in Figure 28 and Figure 29. CSN SCLK 0 MOSI 1 5 6 REGISTER ADDRESS MISO 0 RW 1 30 31 WRITE DATA OR DC PREVIOUS CMD DATA Figure 28: EEPROM Write – SPI Mode SDA SA[6:0] ST A[6:0] D[7:0] D[7:0] D[7:0] D[7:0] Slave W A 0 Register A Register A Register A Register A Register A address C address C Data C Data C Data C Data C K K [7:0] K [15:8] K [23:16] K [31:24] K SP Figure 29: EEPROM Write – I2C Mode Blue represents data sent by the master and orange is the data sent by the slave. Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 23 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging READING The timing diagram for an EEPROM read is shown in Figure 30 and Figure 31. CSN SCLK 0 MOSI 1 5 REGISTER ADDRESS MISO 6 0 RW 1 30 31 WRITE DATA OR DC PREVIOUS CMD DATA Figure 30: EEPROM Read – SPI Mode For SPI, the read data will be sent out during the above command. SDA SA[6:0] ST A[6:0] Slave W A 0 Register A ST address C address C K K SA[6:0] D[7:0] D[7:0] D[7:0] D[7:0] Slave R A Register A Register A Register A Register N address C Data C Data C Data C Data A K [7:0] K [15:8] K [23:16] K [31:24] C K SP Figure 31: EEPROM Read – I2C Mode Blue represents data sent by the master and orange is the data sent by the slave. Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 24 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging EEPROM Error Checking and Correction (ECC) Hamming code methodology is implemented for EEPROM checking and correction (ECC). ECC is enabled after power-up. The ACS37800 analyzes message data sent by the controller and the ECC bits are added. The first 6 bits sent from the device to the controller are dedicated to ECC. The device always returns 32 bits. EEPROM ECC Errors If for any reason the external slave address setting feature is not desired, the DIO polling can be disabled by setting the i2c_dis_ slv_addr. When this bit is set, the ACS37800 will automatically use the number stored in i2c_slv_addr as the I2C slave address regardless of the voltage on the DIO pins. Note that the device must be repowered for these changes to take effect. Table 2: DIO Startup Voltage Addressing A6 A5 A4 A3 A2 A1 A0 Slave Address (decimal) DIO_1 DIO_2 0 0 0 0 1 1 0 0 0 0 0 96 Bits Name Description 31:28 – No meaning 0 0 0 1 1 1 0 0 0 0 1 97 00 = No Error 01 = Error detected and message corrected 10 = Uncorrectable error 11 = No meaning 0 0 1 0 1 1 0 0 0 1 0 98 0 0 1 1 1 1 0 0 0 1 1 99 0 1 0 0 1 1 0 0 1 0 0 100 0 1 0 1 1 1 0 0 1 0 1 101 0 1 1 0 1 1 0 0 1 1 0 102 0 1 1 1 1 1 0 0 1 1 1 103 1 0 0 0 1 1 0 1 0 0 0 104 1 0 0 1 1 1 0 1 0 0 1 105 1 0 1 0 1 1 0 1 0 1 0 106 1 0 1 1 1 1 0 1 0 1 1 107 1 1 0 0 1 1 0 1 1 0 0 108 1 1 0 1 1 1 0 1 1 0 1 109 1 1 1 0 1 1 0 1 1 1 0 27:26 ECC 25:0 D[25:0] EEPROM data I2C Slave Addressing The ACS37800 supports I2C communication over the SCL and SDA lines at speeds of up to 400 kHz. When the device first powers on, it measures the voltage level on the two DIO pins. It converts both voltage levels into a 4-bit code for a total of sixteen slave addresses. Table 2 shows the sixteen possible I2C configurations that can be set with externally applied voltage. If both pins are pulled to VCC, then the internal slave address stored in EEPROM is used. By default, the value of i2c_slv_addr is programmed at the Allegro factory to 127, but this can be changed with programming by the customer. 1 1 1 1 EE EE EE EE EE EE EE 110 EEPROM value Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 25 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging MEMORY MAP Bits iavgselen delaycnt_sel delaycnt_sel n 3 2 1 0 ichan_del_en i2c_slv_addr qvo_fine rms_avg_2 undervreg 4 vevent_cycs sns_fine fault halfcycle_en squarewave_en zerocrossedgesel 0x1F zerocrosschansel 0x1E bypass_n_en fltdly overvreg dio_1_sel crs_sns vchan_offset_code 0x1D Shadow halfcycle_en squarewave_en zerocrosschansel n 0x1B 0x1C undervreg 5 rms_avg_1 ichan_del_en ECC fault i2c_dis_slv_addr 0x0F fltdly 6 rms_avg_1 overvreg vevent_cycs i2c_dis_slv_addr ECC 7 rms_avg_2 chan_del_sel 0x0E vchan_offset_code dio_0_sel ECC 8 qvo_fine chan_del_sel 0x0D 9 sns_fine dio_0_sel ECC crs_sns dio_1_sel 0x0C iavgselen ECC EEPROM 0x0B zerocrossedgesel pavgselen 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 bypass_n_en Address EEPROM/Shadow Memory i2c_slv_addr Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 26 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging ACS37800 Register Details – EEPROM Register 0x0B/0x1B Bits Name Default Value Description 8:0 qvo_fine Device Specific Offset fine trimming on current channel 18:9 sns_fine Device Specific Fine gain trimming on the current channel 21:19 crs_sns Selection Specific 22 iavgselen 0 Current Averaging selection 23 pavgselen 0 Power Averaging selection 31:26 ecc – Error Code Correction Coarse gain setting qvo_fine crs_sns Offset adjustment for the current channel. This is a signed 9-bit number with an input range of –256 to 255. With a step size of 64 LSB, this equates to an offset trim range of –16384 to 16320 LSB, which is added to the icodes value. The current channel’s offset trim should be applied before the gain is trimmed. qvo_fine is further described in Table 3. Coarse gain adjustment for the current channel. This gain is implemented in the analog domain before the ADC. This is a 3-bit number that allows for 8 gain selections. Adjustments to crs_sns may impact the device’s performance over temperature. Datasheet limits apply only to the factory settings for crs_sns. The gain settings map to 1×, 2×, 3×, 3.5×, 4×, 4.5×, 5.5×, and 8×. crs_sns is further described in Table 5. Table 3: qvo_fine Range Value Units –256 to 255 –16,384 to 16,320 LSB sns_fine Gain adjustment for the current channel. This is a signed 9-bit number with an input range of –256 to 255. This gain adjustment is implemented as a percentage multiplier centered around 1 (i.e. writing a 0 to this field multiplies the gain by 1, leaving the gain unaffected). The fine sensitivity parameter ranges from 50% to 150% of IP. The current channel’s offset trim should be applied before the gain is trimmed. sns_fine is further described in Table 4. Table 5: crs_sns Range Value Units 0 1× – 1 2× – 2 3× – 3 3.5× – 4 4× – 5 4.5× – 6 5.5× – 7 8× – iavgselen Table 4: sns_fine Range Value Units –256 to 255 50 to 100 % Current Averaging selection enable. 0 will select vrms for averaging. 1 will select irms for averaging. pavgselen Power Averaging selection enable. 0 will select vrms for averaging. 1 will select pactive for averaging. Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 27 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging Register 0x0C/0x1C Bits Name Default Value Description 6:0 rms_avg_1 0 Average of the rms voltage or current – stage 1 16:7 rms_avg_2 0 Average of the rms voltage or current – stage 2 24:17 vchan_offset_code Device Specific Controls the room offset for the voltage channel 31:26 ecc – Error Code Correction rms_avg_1 vchan_offset_code Number of averages for the first averaging stage (vrmsavgonesec or irmsavgonesec). The value written into this field directly maps to the number of averages ranging from 0 to 127. For optimal performance, an even number of averages should be used. The channel to be averaged is selected by the current average select enable bit (iavgselen). rms_avg_1 is further described in Table 6. This controls the offset of the voltage channel at room. Table 8: vchan_offset_code Range Value Units –128 to 127 –2048 to 2032 codes Table 6: rms_avg_1 Range Value Units 0 to 127 0 to 127 number of averages rms_avg_2 Number of averages for the second averaging stage (vrmsavgonemin or irmsavgonemin). This stage averages the outputs of the first averaging stage. The value written into this field directly maps to the number of averages ranging from 0 to 1023. For optimal performance, an even number of averages should be used. The channel to be averaged is selected by the current average select enable bit (iavgselen). rms_avg_2 is further described in Table 7. Table 7: rms_avg_2 Range Value Units 0 to 1023 0 to 1023 number of averages Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 28 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging ACS37800 Register 0x0D/0x1D Bits Name Default Value Description 7 ichan_del_en 0 Enable phase delay on voltage or current channel 11:9 chan_del_sel 0 Sets phase delay on voltage or current channel 20:13 fault 70 Sets the overcurrent fault threshold 23:21 fltdly 0 Sets the overcurrent fault delay 31:26 ecc – Error Code Correction ichan_del_en Table 12: fltdly Enables delay for either the voltage or current channel. Setting to 1 enables delay for the current channel. ichan_del_en is further described in Table 9. Range Value Units 0 0 µs 1 0 µs 2 4.75 µs Units 3 9.25 µs 13.75 µs Table 9: ichan_del_en Range Value 0 0 – voltage channel LSB 4 1 1 – current channel LSB 5 18.5 µs 6 23.25 µs 7 27.75 µs chan_del_sel Sets the amount of delay applied to the voltage or current channel (set by ichan_del_en). chan_del_sel is further described in Table 10. Table 10: chan_del_sel Range Value Units 0 to 7 0 to 219 µs fault Over-current fault threshold. This is an unsigned 8-bit number with an input range of 0 to 255, which equates to a fault range of 65% to 200% of IP. The factory setting of this field is 70. fault is further described in Table 11. Table 11: fault Range Value Units 0 to 255 56 to 225 % of IP fltdly Fault delay setting of the amount of delay applied before flagging a fault condition. fltdly is further described in Table 12. Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 29 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging Register 0x0E/0x1E Bits Name Default Value Description 5:0 vevent_cycs 0 Sets the number of qualifying cycles needed to flag overvoltage or undervoltage 13:8 overvreg 0 Sets the overvoltage fault threshold 19:14 undervreg 0 Sets the undervoltage fault threshold 20 delaycnt_sel 0 Sets the width of the voltage zero-crossing output pulse 21 halfcyclc_en 0 Sets the zero crossing flag triggering on half or full cycle (default: full cycle) 22 squarewave_en 0 Sets the zero crossing pulse characteristics (default: pulse) 23 zerocrosschansel 0 Sets the channel that triggers the zero crossing flag (default: voltage) 24 zerocrossedgesel 0 Sets the edge that triggers zero crossing flag 31:26 ecc – Error Code Correction vevent_cycs delaycnt_sel Sets the number of cycles required to assert the ovrms flag or the uvrms. This is an unsigned 6-bit number with an input range of 0 to 63. The value in this field directly maps to the number of cycles. vevent_cycs is further described in Table 13. Selection bit for the width of pulse for a voltage zero-crossing event. When set to 0, the pulse is 32 µs. When set to 1, the pulse is 256 µs. When the squarewave_en bit is set, this field is ignored. delaycnt_sel is further described in Table 16. Table 13: vevent_cycs Table 16: delaycnt_sel Range Value Units Range 0 to 63 1 to 64 cycles overvreg Value Units 0 32 µs 1 256 µs Sets the threshold of the overvoltage rms flag (ovrms). This is a 6-bit number ranging from 0 to 63. This trip level spans the entire range of the vrms register. The flag is set if the rms value is above this threshold for the number of cycles selected in vevent_cycs. overvreg is further described in Table 14. halfcycle_en Table 14: overvreg squarewave_en Range Value Units 0 to 63 0 to 65536 LSB undervreg Sets the threshold of the undervoltage rms flag (uvrms). This is a 6-bit number ranging from 0 to 63. This trip level spans one entire range of the vrms register. The flag is set if the rms value is below this threshold for the number of cycles selected in vevent_ cycs. undervreg is further described in Table 15. Table 15: undervreg Range Value Units 0 to 63 0 to 65536 LSB Setting for the zero crossing flag. When set to 0, the voltage zero-crossing will be indicated on every edge determined by zerocrossingedgesel. When set to 1, the voltage zero-crossing will be indicated on both rising and falling edges. Setting for the zero crossing flag. When set to 0, the zero-crossing event will be indicated by a pulse on the DIO pin. When set to 1, the zero-crossing event will be indicated by a level change on the DIO pin. zercrossingchansel Determines which channel will trigger the zero crossing flag. 0 is the voltage channel. 1 is the current channel with zero crossing flag for rising and falling with only one customizable register delaycnt_sel. zerocrossingedgesel This determines whether the zero crossing flag triggers on rising or falling. Note: if halfcycle_en = 1, this setting does not matter. Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 30 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging Register 0x0F/0x1F Bits Name Default Value Description 8:2 i2c_slv_addr 127 9 i2c_dis_slv_addr 0 Disable I2C slave address selection circuit I2C slave address selection 11:10 dio_0_sel 0 Digital output 0 multiplexor selection bits 13:12 dio_1_sel 0 Digital output 1 multiplexor selection bits 23:14 n 0 Sets the number of samples used in RMS calculations when bypass_n_en = 1 24 bypass_n_en 0 Set whether RMS is calculated based on voltage zero crossing or n samples from the above registers 31:26 ecc – Error Code Correction i2c_slv_addr i2c_dis_slv_addr I2C Settings for the slave address externally. When i2c_dis_slv_ addr is set to 0, the voltage on the DIO pins are measured at power on and are used to set the device’s slave address. Each DIO pin has 4 voltage “bins” which may be used to set the I2C slave address. These voltages may be set using resistor divider circuits from VCC  to GND. i2c_slv_addr is further described in Table 17. Table 17: i2c_slv_addr DIO_1 (decimal) 0 0 0 0 1 1 1 1 2 2 2 2 3 3 3 3 DIO_0 (decimal) 0 1 2 3 0 1 2 3 0 1 2 3 0 1 2 3 Slave Address (decimal) 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 EEPROM value When i2c_dis_slv_addr is set to 1, the address is set through EEPROM field i2c_slv__addr[6:0]. This enables or disables the analog I2C slave address feature at power on. When this bit is set, the I2C slave address will map directly to i2c_slv_addr. dio_0_sel Determines which flags are output on the DIO0 pin. Only used when the device is in I2C programming mode. dio_1_sel Determines which flags are output on the DIO1 pin. Only used when the device is in I2C programming mode. Ratio of VCC on DIO Pin Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 31 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging ACS37800 9 8 7 vrms pimag pactive 0x22 pospf irms 0x21 posangle 0x20 pfactor 6 5 3 2 1 faultout 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 faultlatched Bits overvoltage Address Volatile Memory 4 0 papparent 0x23 0x24 0x25 numptsout 0x26 irmsavgonesec vrmsavgonesec 0x27 irmsavgonemin vrmsavgonemin 0x28 pactavgonesec pactavgonemin icodes vcodes 0x2B 0x2C 0x2D vzerocrossout pinstant undervoltage 0x2E 0x2F access_code customer_access VOLATILE 0x29 0x2A 0x30 0x31 Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 32 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging Register Details – Volatile Register 0x20 Bits Name Description 15:0 vrms Voltage RMS value 31:16 irms Current RMS value vrms irms RMS voltage output. This field is an unsigned 16-bit fixed point number with 16 fractional bits, where ΔVIN(MAX) = 0.84, and ΔVIN(min) = –0.84. To convert the value (input voltage) to line voltage, divide the input voltage by the RSENSE and RISO voltage divider ratio using actual resistor values. RMS current output. This field is a signed 16-bit fixed point number with 15 fractional bits, where IIP(MAX) = 0.84, and IIP(MIN)= -0.84. Table 18: vrms Register Range Valid Range Value Units 0 to ~1 0 to ~0.84 [0 to ~1] × ΔVIN(MAX) ×1.19 mV Table 19: irms Register Range Valid Range Value Units 0 to ~1 0 to ~0.84 [0 to ~1] × IPR(MAX) ×1.19 A Register 0x21 Bits Name Description 15:0 pactive Active power 31:16 pimag Reactive power pactive pimag Active power output. This field is a signed 16-bit fixed point number with 15 fractional bits, where positive MaxPow = 0.704, and negative MaxPow = –0.704. To convert the value (input power) to line power, divide the input power by the RSENSE and RISO voltage divider ratio using actual resistor values. Reactive power output. This field is an unsigned 16-bit fixed point number with 16 fractional bits, where MaxPow = 0.704. To convert the value (input power) to line power, divide the input power by the RSENSE and RISO voltage divider ratio using actual resistor values. Table 20: pactive Table 21: pimag Register Range Valid Range Value Units Register Range Valid Range Value Units –1 to ~1 –0.704 to ~0.704 [1 to ~1] × MaxPow × 1.42 mW 0 to ~1 0 to ~0.704 [0 to ~1] × MaxPow × 1.42 mVA Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 33 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging Register 0x22 Bits Name Description 15:0 papparent 26:16 pfactor Apparent power magnitude 27 posangle Sign of the power angle 28 pospf Sign of the power factor Power factor papparent posangle Apparent power output magnitude. This field is an unsigned 16-bit fixed point number with 16 fractional bits, where MaxPow = 0.704. To convert the value (input power) to line power, divide the input power by the RSENSE and RISO voltage divider ratio using actual resistor values. Bit to represent leading or lagging. A 0 represents the current leading and a 1 represents the current lagging. Table 22: papparent Register Range Valid Range Value Units 0 to ~1 0 to ~0.704 [0 to ~1] × MaxPow × 1.42 mVAR pospf Sign bit to represent if the power is being generated (0) or consumed (1). pfactor Power factor output. This field is a signed 11-bit fixed point number with 10 fractional bits. It ranges from –1 to ~1 with a step size of 2-10. pfactor is further described in Table 23. Table 23: pfactor Range Value Units –1 to ~1 –1 to ~1 – Register 0x25 Bits Name 9:0 numptsout Description Number of samples of current and voltage used for calculations numptsout Number of points used in the rms calculation. This will be the dynamic value that is evaluated internal to the device based on full cycle zero crossings of the voltage channel. numptsout is further described in Table 24. Table 24: numptsout Range Value Units 0 to 1023 0 to 1023 samples Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 34 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging Register 0x26 Bits Name Description 15:0 vrmsavgonesec Averaged voltage RMS value; duration set by rms_avg_1. This register will be zero if iavgselen = 1 31:16 irmsavgonesec Averaged current RMS value; duration set by rms_avg_1. This register will be zero if iavgselen = 0 vrmsavgonesec irmsavgonesec Voltage RMS value averaged according to rms_avg_1. This register will be zero if iavgselen = 1. Current RMS value averaged according to rms_avg_1. This register will be zero if iavgselen = 0. Register 0x27 Bits Name Description 15:0 vrmsavgonemin Averaged voltage RMS value; duration set by rms_avg_2. This register will be zero if iavgselen = 1 31:16 irmsavgonemin Averaged current RMS value; duration set by rms_avg_2. This register will be zero if iavgselen = 0 vrmsavgonemin irmsavgonemin Voltage RMS value averaged according to rms_avg_2. This register will be zero if iavgselen = 1. Current RMS value averaged according to rms_avg_2. This register will be zero if iavgselen = 0. Register 0x28 Bits Name 15:0 pactavgonesec Description Active Power value averaged over up to one second; duration set by rms_avg_1 pactavgonesec Active power value averaged according to rms_avg_1. Register 0x29 Bits Name 15:0 pactavgonemin Description Active Power value averaged over up to one minute; duration set by rms_avg_2 pactavgonemin Active power value averaged according to rms_avg_2. Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 35 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging Register 0x2A Bits Name Description 15:0 vcodes Instantaneous voltage measurement 31:16 icodes Instantaneous current measurement vcodes This field contains the instantaneous voltage measurement before any RMS calculations are done. It is a 16-bit signed fixed point number with 15 fractional bits, where ΔVIN(MAX) = 0.84 and ΔVIN(min) = –0.84. To convert the value (input voltage) to line voltage, divide the input voltage by the RSENSE and RISO voltage divider ratio using the resistor values. Table 25: vcodes Register Range Valid Range Value Units –1 to ~1 -0.84 to ~0.84 [–1 to ~1] × ΔVIN(MAX) ×1.19 mV icodes This field contains the instantaneous current measurement before any RMS calculations are done. This field is a signed 16-bit fixed point number with 15 fractional bits, where IIP(MAX) = 0.84, and IIP(MIN)= –0.84. Table 26: icodes Register Range Valid Range Value Units –1 to ~1 -0.84 to ~0.84 [–1 to ~1] × IPR(MAX) ×1.19 A Register 0x2C Bits Name 15:0 pinstant Description Instantaneous power – Multiplication of vcodes and icodes pinstant This field contains the instantaneous power measurement before any RMS calculations are done. This field is a signed 16-bit fixed point number with 15 fractional bits, where postive MaxPow = 0.704, and negative MaxPow = –0.704. To convert the value (input power) to line power, divide the input power by the RSENSE and RISO voltage divider ratio using the resistor values. Table 27: pinstant Register Range Valid Range Value Units –1 to ~1 –0.704 to ~0.704 [–1 to ~1] × MaxPow × 1.42 mVAR Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 36 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging Register 0x2D Bits Name 0 zerocrossout Description Zero-crossing output 1 faultout 2 faultlatched Current fault output Current fault output latched 3 overvoltage Overvoltage flag 4 undervoltage Undervoltage flag zerocrossout overvoltage Flag for the zero-crossing events. This will be present and active regardless of DIO_0_sel and DIO_1_sel. This flag will still follow the halfcycle_en and squarewave_en settings. Flag for the overvoltage events. This will be present and active regardless of DIO_0_sel and DIO_1_sel and will only be set when fault is present. faultout undervoltage Flag for the overcurrent events. This will be present and active regardless of DIO_0_sel and DIO_1_sel and will only be set when fault is present. Flag for the undervoltage events. This will be present and active regardless of DIO_0_sel and DIO_1_sel and will only be set when fault is present. faultlatched Flag for the overcurrent events. This bit will latch and will remain 1 as soon as an overcurrent event is detected. This can be reset by writing a 1 to this field. This will be present and active regardless of DIO settings. Register 0x2F Bits Name 31:0 access_code Description Access code register: Customer code: 0x4F70656E Register 0x30 Bits Name 0 customer_access Description Customer write access enabled. 0 = Non-Customer mode. 1 = Customer mode. Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 37 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging THERMAL PERFORMANCE The thermal capacity of the ACS37800 should be verified by the Thermal Rise vs. Primary Current Self-heating due to the flow of current should be considered during the design of any current sensing system. The sensor, printed circuit board (PCB), and contacts to the PCB will generate heat as current moves through the system. The thermal response is highly dependent on PCB layout, copper thickness, cooling techniques, and the profile of the injected current. The current profile includes peak current, current “on-time”, and duty cycle. While the data presented in this section was collected with direct current (DC), these numbers may be used to approximate thermal response for both AC signals and current pulses. The plot in Figure 32 shows the measured rise in steady-state die temperature of the ACS37800 versus continuous current at an ambient temperature, TA, of 25 °C. The thermal offset curves may be directly applied to other values of TA. Conversely, Figure 33 shows the maximum continuous current at a given TA. Surges beyond the maximum current listed in Figure 33 are allowed given the maximum junction temperature, TJ(MAX) (165℃), is not exceeded. end user in the application’s specific conditions. The maximum junction temperature, TJ(MAX) (165℃), should not be exceeded. Further information on this application testing is available in the DC and Transient Current Capability application note on the Allegro website. ASEK37800 Evaluation Board Layout Thermal data shown in Figure 32 and Figure 33 was collected using the ASEK37800 Evaluation Board (TED-0003306). This board includes 750 mm2 of 4 oz. copper (0.0694 mm) connected to pins 1 through 4, and to pins 5 through 8, with thermal vias connecting the layers. Top and Bottom layers of the PCB are shown below in Figure 34. Change in Die Temperature (°C) 140 120 100 80 60 40 20 0 0 10 20 30 40 50 60 70 Continuous Current (A) Continuous Current (A) Figure 32: Self Heating in the MA Package Due to Current Flow 80 70 60 50 40 30 20 10 0 25 50 75 100 125 150 175 Ambient Temperature (°C) Figure 33: Maximum Continuous Current at a Given TA Figure 34: Top and Bottom Layers for ASEK37800 Evaluation Board Gerber files for the ASEK37800 evaluation board are available for download from the Allegro website. See the technical documents section of the ACS37800 device webpage. Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 38 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging RECOMMENDED PCB LAYOUT NOT TO SCALE All dimensions in millimeters. 15.75 9.54 0.65 1.27 Package Outline Slot in PCB to maintain >8 mm creepage once part is on PCB 2.25 7.25 1.27 3.56 17.27 Current Out Current In 21.51 Perimeter holes for stitching to the other, matching current trace design, layers of the PCB for enhanced thermal capability. Figure 35: Recommended PCB Layout Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 39 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging ACS37800 PACKAGE OUTLINE DRAWING For Reference Only – Not for Tooling Use (Reference MS-013AA) NOT TO SCALE Dimensions in millimeters Dimensions exclusive of mold flash, gate burrs, and dambar protrusions Exact case and lead configuration at supplier discretion within limits shown 8° 0° E 10.30 ±0.20 16 0.33 0.20 D D1 D2 7.50 ±0.10 10.30 ±0.33 A 1 1.27 1.40 REF 0.40 2 D 0.90 Branded Face 0.25 BSC SEATING PLANE 16× C 2.65 MAX 0.10 C GAUGE PLANE SEATING PLANE 0.30 0.10 1.27 BSC 0.51 0.31 0.65 1.27 16 XXXXXXX Lot Number 2.25 1 9.50 B Standard Branding Reference View Lines 1, 2 = 12 characters Line 1: Part Number Line 2: First 8 characters of Assembly Lot Number 1 C 2 PCB Layout Reference View 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 D Hall elements (D1, D2), not to scale E Active Area Depth 0.293 mm Figure 36: Package MA, 16-Pin SOICW Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 40 ACS37800 Isolated, Digital Output, Power Monitoring IC with Zero-Crossing Detection, Overcurrent and Overvoltage Flagging Revision History Number Date Description – November 30, 2020 Initial release 1 January 27, 2021 Updated Part Numbering schematic (page 2), Supply Bypass Capacitor unit, Current Channel Power Supply Error test conditions (page 6), Figure 4 (page 12), Figure 9 (page 15), and Figure 21 (page 21). 2 February 24, 2021 Removed TUV certificate mark (page 1) Copyright 2021, Allegro MicroSystems. Allegro MicroSystems reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the information being relied upon is current. Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems assumes no responsibility for its use; nor for any infringement of patents or other rights of third parties which may result from its use. Copies of this document are considered uncontrolled documents. For the latest version of this document, visit our website: www.allegromicro.com Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com 41