Current sensors Open-Loop Low-Cost Current Sensor ROR / January 2007 © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved Melexis “Hall” Engine Management - Hall Sensors “Contactless” Current Sensing Vout l0 Conventional Hall Plate I Current Conductor Features: Small and Simple construction, Programmable, Low cost BW <100kHz, Robust / Over current resistant Current Monitoring/Failure Detection/Over Current Protection © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved Tria⊗ ⊗is Hall Conventional Hall Opportunities based on IMC Applications / Identified Opportunities: - Over current protection, failure detection, electronic fuse - BCM Battery Management - HEV Hybrid “Inverters” © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved - Current sensing/monitoring on PCB or Bus bar (BLDC Motors) Conventional Current Sensors Open Loop Current Sensor - AC/DC; BW < 10- 50 kHz Accuracy <3-5% error Material non linearity Temperature drift 1 0 -200 -100 0 -1 -2 current [A] 200 Soft Ferromagnetic Core Vout l0 I 100 © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved Features 2 output signal [V] Air gap: B ≈ I * µ0 / l0 Vout = S * B Open Loop Current Sensor: Non-linearity due to B-H-curve of core material Conventional Hall Plate Current Conductor IMC Current Sensor Factory-Programmed Current Sensor CSA-1V µ0 B ≈ * I amps 2π * r 3 V~I V out diff V -1 N A O S R C NT E S B 2 1 0 -1 -2 I -3 -10 -7.5 -5 -2.5 0 2.5 5 Magnetic field mT Contact-less, low-cost, open-loop, pcb-mounting © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved Differential output V 7.5 10 IMC Current Sensor IMC-Hall-ASIC: CSA-1 Photograph of ASIC with attached twin IMC The IMC transforms a lateral field locally into a vertical field © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved IMC=Integrated Magnetic Concentrator IMC Current Sensor Conventional Hall ASICs are made of CMOS integrated circuits containing lateral Hall elements at the surface Due to the nature of the Hall elements these sensors are only sensitive to a magnetic field perpendicular to the chip surface © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved IMC Hall Working Principle We structure Integrated Magnetic Concentrators (IMC) made of soft ferromagnetic material on the chip surface ! Then the flux lines go in here And they come out here Part of the flux lines pass through the chip underneath the gap © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved IMC Current Sensor IMC Current Sensor Benefits of the IMC Technology ► easier mounting of sensor for many applications ► new opportunities for combining sensor and current lead locally increased flux density (magnetic gain) ► higher output signal ► lower field equivalent offset ► lower field equivalent noise IMC boosts the the performance of CMOSCMOS-HallHall-Sensors © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved sensitive parallel with chip surface IMC Current Sensor B~I Conductor below sensor (PCB mount) Conductor above sensor © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved Application: Current Sensor IMC Current Sensor The backside ferromagnetic shield guides the external flux lines (blue) around the sensor and it increases magnetic susceptibility for the flux lines emanating from the current conductor (red). In such a way sensitivity is enhanced by 3040%. © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved Shielding techniques: simple flat plate or u-formed permalloy. IMC Current Sensor Sensitivity: 40mV/Amp, Range: ± 50 Amp, Resolution: 0.08Amp (@10khz) © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved Example: IMC Current Sensor (50A) IMC Current Sensor Sensitivity: 10mV/Amp, Range: ± 200 Amp, Resolution: 0.3 Amp (@10khz) © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved Example: IMC Current Sensor (200A) Demonstrator: 200A Current Sensor Measurement Results Current sensor demonstrator: Sensor output and nonlinearity vs. buss bar current; 3x10mm buss bar; U-shape MuMetal shield y = 22.113x - 4.7486 R2 = 1 1 800 0.8 600 0.6 400 0.4 200 0.2 0 0 -40 -30 -20 -10 -200 0 10 20 30 40 -0.2 -400 -0.4 -600 -0.6 -800 -0.8 -1000 bussbar current [A] -1 non linearity [%FS] output voltage [mV] 1000 © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved Sensitivity: 22mV/A IMC Current Sensor 12mV Saturation Level 10 .. 90% Rise time = 3.5ｵ 3.5ｵ s 0 .. 10% Response time = 3ｵ 3ｵ s © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved CSA-1V Performance: Response Time IMC Current Sensor • Full-scale range: • linearity: • Freq. Range: 1 - 1000 Amps about +/- 0.6% for F.S. Range DC-100 kHz • Temp. drift of Offset: < 0.15mV/°C corresponds to +/-1% for +/- 100°C • Temp. drift of Sensitivity: <200ppm/°C corresponds to +/- 2% for +/- 100°C © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved CSA-1V Performance Conclusion: Conclusion V Features - Small size - Simple construction - Low cost - BW <100kHz - Robust, Over current resistant V~I SE CSA NT -1 V RO N B I © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved Open Loop IMC Current Sensor CSA-1V Current Measurement based on IMC - contact less and very small dimension does not require slotted torroid ( simple shield) standard assembling technique on pcb high modularity (adapt Sensor/conductor/shield) IMC give magnetic gain -> higher S/N; very low Br-Hc effect High bandwidth (based on CSA-1) © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved USP ( features of IMC Hall (CSA-1): I © Copyright Melexis Microelectronic Integrated Systems. All Rights Reserved Hall Effect Based Current Sensors We will be happy to discuss with you your application ! Please contact for shielding support as well as more technical details: Robert Racz ([email protected])