ATS675LSE Self-Calibrating TPOS Speed Sensor IC Optimized for Automotive Cam Sensing Applications Features and Benefits Description Optimized for automotive camshaft sensing True target state recognition at device power-on (TPOS) and at zero target speed Chopper stabilization reduces offset drift Digital output polarity option: follow or invert target profile Rapid calibration and transition to Running mode Automatic Gain Control (AGC) during calibration eliminates effects of air gap variations Tight timing accuracy over full operating temperature range Operation at supply voltages as low as 3.3 V Undervoltage lockout (UVLO) The ATS675 is a next generation member of the Allegro(R) True Power-On State (TPOS) sensor IC family, offering improved accuracy compared to prior generations, and performing at absolutely zero target speed. An output polarity option allows customization for specific applications. The device incorporates a single Hall-element IC with an optimized custom magnetic circuit that switches in response to magnetic signals. The resulting output of the device is a digital representation of a ferromagnetic target profile. The IC contains a sophisticated digital circuit designed to eliminate the detrimental effects of magnetic and system offsets. Signal processing is used to provide target state recognition at zero rotational speed, consistent switchpoints regardless of air gap, and dynamically adapt device performance to the typical operating conditions found in automotive environments, particularly cam sensing applications. Package: 4-pin SIP (suffix SE) High-resolution peak-detecting DACs are used to set the adaptive switching thresholds of the device. The ATS675 also includes a filter that increases the noise immunity and the signal-to-noise ratio of the IC. The device is provided in a 4-pin SIP package (SE) that is lead (Pb) free with 100% matte tin leadframe plating. Not to scale Typical Application VS VPU CBYPASS 0.1 F RPU 1 VCC 3 A ATS675 TEST OUT GND 4 2 Output CL A Recommended Figure 1. Operational circuit for the ATS675 ATS675LSE-DS, Rev. 2 ATS675LSE Self-Calibrating TPOS Speed Sensor IC Optimized for Automotive Cam Sensing Applications Selection Guide Part Number Output Protocol ATS675LSETN-LT-T Output low opposite target tooth ATS675LSETN-HT-T Output high opposite target tooth *Contact Allegro for additional packing options Packing* 13-in. reel, 450 pieces per reel Absolute Maximum Ratings Characteristic Symbol Rating Unit 28 V VRCC -18 V Reverse Output Voltage VROUT -0.5 V Reverse Supply Current IRCC -50 mA 30 mA -50 mA Supply Voltage VCC Reverse Supply Voltage Output Current Reverse Output Current IOUT(sink) Notes Refer to Power Derating curve Internal current limiting is intended to protect the device from output short circuits, but is not intended for continuous operation. IROUT Operating Ambient Temperature TA -40 to 150 C Maximum Junction Temperature TJ(max) 165 C Tstg -65 to 170 C Storage Temperature Range L Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 2 Self-Calibrating TPOS Speed Sensor IC Optimized for Automotive Cam Sensing Applications ATS675LSE Functional Block Diagram VCC Regulator (Analog) Running Mode Threshold Regulator (Digital) Baseline Trim Oscillator Hall Amp +/- Low Pass Filter NDAC Update Logic +/- PDAC DDA Multiplexed Test Signals TEST Running Mode Threshold Selector OUT Sensitivity TC Compensation Automatic Gain Adjust TPOS Trim Mode Control Dynamic Threshold DAC Current Limit TPOS GND Pin-out Diagram Terminal List 1 2 3 Number Name Function 1 VCC Supply voltage 2 OUT Open drain output 3 TEST Test pin; connection to GND recommended 4 GND Ground 4 Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 3 ATS675LSE Self-Calibrating TPOS Speed Sensor IC Optimized for Automotive Cam Sensing Applications OPERATING CHARACTERISTICS Valid using reference target 8X, TA ,TJ , and VCC within specification, unless otherwise noted Characteristics Symbol Test Conditions Min. Typ.1 Max. Unit Electrical Characteristics Supply Voltage2 Undervoltage Lockout VCC Operating, TJ < TJ(max) 3.3 - 24 V VCCUV VCC = 0 5 V or 5 0 V - - 3.3 V Supply Zener Clamp Voltage VZSUPPLY ICC = ICC(max) + 3 mA, TA = 25C 28 33 40 V Supply Zener Current3 IZSUPPLY VSUPPLY = 28 V - - 13 mA - 6.5 10 mA - - -10 mA fc - 500 - kHz VZTEST - 6 - V - - 1 ms Supply Current ICC Reverse Battery Current4 IRCC Chopping Frequency TEST Pin Zener Clamp Voltage5 VRCC = -18 V Power-On Characteristics Power-On Time6 tPO VCC > VCC(min), fSIG < 200 Hz Output Stage Characteristics Output Profile Polarity7 Output On Voltage VOUT(SAT) LT option, measured as VOUT , device electrically connected as in figure 1 Opposite to Tooth (Output State = On) - Low - V Opposite to Valley (Output State = Off) - High - V HT option, measured as VOUT , device electrically connected as in figure 1 Opposite to Tooth (Output State = Off) - High - V Opposite to Valley (Output State = On) - Low - V - - 400 mV mV IOUT = 10 mA, Output State = On IOUT = 15 mA, Output State = On - - 450 Output Zener Voltage VZOUT TA = 25C, IOUT = 3 mA 30 - - V Output Current Limit IOUTLIM Output State = On 30 50 80 mA Output Leakage Current IOUTOFF VOUT = 24 V, Output State = Off - - 10 A RPU = 1 k, CL = 4.7 nF, VPU = 5 V - 10 - s VPU = 5 V 0.8 1.1 1.5 s VPU = 12 V - 1.6 - s Output Rise Time tr Output Fall Time8 tf(OUT) Measured from 90% to 10%, TA = 25C, RPU = 1 k, CL = 4.7 nF, (see figure 2) Output Fall Time Variation with Temperature tf(OUT) Maximum variation from TA = 25C to -40C and then to 150C - 20 - % Output Delay Time9 td(OUT) 4 kHz sinusoidal input signal, falling electrical edge (see figure 2) - 18 - s TPOS functionality guaranteed 0.5 - 3.0 mm Output switching in Running mode, TPOS function not guaranteed 3.0 - 4.5 mm Performance Characteristics Operational Air Gap Range10 Extended Air Gap Range11 AGTPOS AGEXTMAX Analog Signal Bandwidth BW Equivalent to -3 dB cutoff frequency - 20 - kHz Tooth Speed fSIG Tooth signal frequency, sinusoidal input signal 0 - 8000 Hz Continued on the next page... Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 4 ATS675LSE Self-Calibrating TPOS Speed Sensor IC Optimized for Automotive Cam Sensing Applications OPERATING CHARACTERISTICS (continued) Valid using reference target 8X, TA , TJ , and VCC within specification, unless otherwise noted Characteristics Min. Typ.1 Max. Unit - 1 3 edge - - 1 tooth % of peak-to-peak, referenced to tooth signal (see figure 4) - 30 - %pk-pk % of peak-to-peak signal - 10 - % Reduction in VPROC amplitude from VPROC(high) to lowest peak VPROC(reduce), all specifications within range (see figure 3) - - 15 %pk-pk Reduction in VPROC amplitude from VPROC(high) to lowest peak VPROC(reduce); output switches, other specifications may be out of range (see figure 3) - - 25 %pk-pk ErrRELR Rising mechanical edges after initial calibration, gear speed = 1000 rpm, target eccentricity < 0.1 mm - 0.4 0.8 deg. ErrRELF Falling mechanical edges after initial calibration, gear speed = 1000 rpm, target eccentricity < 0.1 mm - 0.5 1.0 deg. Symbol Test Conditions Calibration7 Initial Calibration12,13 TPO to Running Mode Adjustment CALI Quantity of mechanical falling edges used to determine Running mode switchpoints level Quantity of mechanical falling edges after CALI CALTPORM to transition from TPOS switchpoints level to Running mode switchpoints level Running Mode Switchpoint Characteristics Running Mode Switchpoint Internal Hysteresis BST BHYS(int) Signal Characteristics Maximum Allowable Signal Reduction14 Relative Breduce Timing Accuracy12,15 1Typical values are at TA = 25C and VCC = 12 V. Performance may vary for individual units, within the specified maximum and minimum limits. voltage must be adjusted for power dissipation and junction temperature; see Power Derating section. 3Maximum current limit is equal to I (max) + 3 mA. CC 4Negative current is defined as conventional current coming out of (sourced from) the specified device terminal. 5Sustained voltages beyond the clamp voltage may cause permanent damage to the IC. 6Power-On Time is the duration from when V CC rises above VCC(min) until a valid output state is realized. 7For additional information see the Functional Description section. 8Characterization data shows 12 V fall time to be 1.5 times longer than 5 V fall time. See figure 2. 9Output Delay Time is the duration from when a crossing of the magnetic signal switching level, B , occurs to when the electrical output signal, V ST OUT , reaches 90% of VOUT(high). 10The Operational Air Gap Range is the range of installation air gaps within which the TPOS (True Power-On State) function is guaranteed to correctly detect a tooth when powered-on opposite a tooth and correctly detecting a valley when powered-on opposite a valley, using reference target 8X. 11The Extended Air Gap Range is a range of installation air gaps, larger than AG TPOS, within which the device will accurately detect target features in Running mode, but TPOS functionality is NOT guaranteed, possibly resulting in undetected target features during Initial Calibration. Relative Timing Accuracy (ErrREL) not guaranteed in Extended Air Gap Range. 12The term mechanical edge refers to a target feature, such as the side of a gear tooth, passing opposite the device. A rising edge is a transition from a valley to a tooth, and a falling edge is a transition from a tooth to a valley. See figure 6. 13Signal frequency for CAL is f I SIG < 200 Hz. 14Running mode; 4X target used. The Processed Internal Signal, V PROC , is the internal signal generated by the Hall detection circuitry and normalized by Automatic Gain Control. 15Relative Timing Accuracy refers to the difference in accuracy, relative to a 0.5 mm air gap, through the entire Operational Air Gap Range, after initial calibration; gear speed = 1000 rpm, target eccentricity < 0.1 mm. See figure 7. 2Maximum Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 5 Self-Calibrating TPOS Speed Sensor IC Optimized for Automotive Cam Sensing Applications Processed Input Signal, VPROC Definitions of Operating Characteristics VPROC(high) VPROC(BOP) , VPROC(BRP) td(OUT) VPROC(low) Time Output Signal, VOUT tf(OUT) VOUT(high) 90% VOUT 10% VOUT VOUT(low) Time Figure 2. Definition of Output Delay Time, td(OUT) , and Output Fall Time, tf(OUT) . Highest peak |B| Signal Reduction Magnetic Signal, BSIG (G) ATS675LSE 0 Breduce (%) = Lowest peak Time BSIG Highest Peak - BSIG Lowest Peak BSIG Highest Peak x 100 Figure 3. Definition of Maximum Allowable Signal Reduction, Breduce , as a percentage of the overall magnetic signal. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 6 Self-Calibrating TPOS Speed Sensor IC Optimized for Automotive Cam Sensing Applications ATS675LSE Characteristic Performance Supply Current versus Ambient Temperature Output Fall Time versus Ambient Temperature RPU = 1 k, CL = 4.7 nF 10 3.0 2.5 8 VCC (V) 7 3.3 15.0 24 tf(OUT) (s) ICC (mA) 9 1.0 5 0.5 -25 0 25 50 75 100 TA (C) 125 150 0 -50 175 0.4 350 0.3 VOUT(sat) (mV) IOUT (mA) 20 15 10 200 150 Edge Position () 400 250 50 75 100 TA (C) 125 150 0.4 0.4 0.3 0.3 TA (C) -40 0 25 85 150 0 -0.1 -0.2 175 1 1.5 2 AG (mm) 2.5 3 3.5 0.2 Mechanical Edge Falling Rising 0.1 0 -0.1 -0.2 -0.3 -0.4 0.5 150 Relative Timing Accuracy versus Speed TA = 25C, 1.5 mm Air Gap, Relative to 0.5 mm Air Gap Edge Position () Edge Position () Relative Timing Accuracy versus Air Gap Rising Mechanical Edge, 1000 rpm, Relative to 0.5 mm Air Gap 0.1 125 TA (C) -40 0 25 85 150 -0.4 0.5 175 0.2 75 100 TA (C) 0 -0.3 25 50 -0.1 -0.2 0 25 0.1 50 -25 0 0.2 100 0 -50 -25 Relative Timing Accuracy versus Air Gap Falling Mechanical Edge, 1000 rpm, Relative to 0.5 mm Air Gap Output Voltage (Low) versus Ambient Temperature 300 5 12 24 1.5 6 4 -50 VPU (V) 2.0 -0.3 1 1.5 2 AG (mm) 2.5 3 3.5 -0.4 0 500 1000 1500 2000 2500 Gear Speed (rpm) Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 7 Self-Calibrating TPOS Speed Sensor IC Optimized for Automotive Cam Sensing Applications ATS675LSE Thermal Characteristics may require derating at maximum conditions, see application information Characteristic Symbol Test Conditions* RJA Package Thermal Resistance Value Units 1-layer PCB with copper limited to solder pads 101 C/W 2-layer PCB with copper limited to solder pads and 3.57 in.2 of copper area each side 77 C/W *Additional thermal information available on the Allegro website Power Derating Curve 30 Maximum Allowable VCC (V) 25 VCC(max) 20 (RQJA = 77 C/W) 15 (RQJA = 101 C/W) 10 5 VCC(min) 0 20 40 60 80 100 120 140 160 180 Temperature, TA (C) Power Dissipation, PD (mW) Power Dissipation versus Ambient Temperature 1900 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 (R QJ A = 77 (R QJ 20 40 60 A =1 01 C /W C /W ) ) 80 100 120 140 Temperature, TA (C) 160 180 Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 8 Self-Calibrating TPOS Speed Sensor IC Optimized for Automotive Cam Sensing Applications ATS675LSE Reference Target 8x Test Conditions Typ. Unit Do Outside diameter of target 120 mm Face Width F Breadth of tooth, with respect to branded face 6 mm Circular Tooth Length t Length of tooth, with respect to branded face; measured at Do 23.6 mm Circular Valley Length tv Length of valley, with respect to branded face; measured at Do 23.6 mm Tooth Whole Depth ht 5 mm - - Symbol Key Branded Face of Package ODO ht F t Outside Diameter Symbol tV Characteristic Material CRS 1018 Air Gap Branded Face of Package Reference Target 8X Figure 4. Configuration with Reference Target Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 9 Self-Calibrating TPOS Speed Sensor IC Optimized for Automotive Cam Sensing Applications ATS675LSE Functional Description Output Profile Polarity (LT/HT Option) Device output, VOUT , is a digital representation of the mechanical profile of the target, as illustrated in figure 6. The customer can choose the relative polarity of the output waveform. This assigns the polarity opposite tooth features (the inverse polarity Target (Gear) Automatic Gain Control (AGC) The Automatic Gain Control (AGC) feature ensures that the ATS675 initial switching thresholds are isolated from the effects of changes in the effective air gap (the total distance between the Hall element and the nearest feature of the target). AGC is implemented by unique patented self-calibrating circuitry, and normalizes the sensed magnetic gradient so the internal processed signal falls within the optimum processing range. Device power-on Target Mechanical Profile Tooth Hall Technology The ATS675 contains a single-chip Hall effect sensor IC, a 4-pin leadframe, a specially designed rare-earth pellet, and a ferrous pole piece (a precisely-mounted magnetic field concentrator). The Hall IC supports a chopper stabilized Hall element that measures the magnetic gradient created by the passing of a ferromagnetic object. This is illustrated in figure 5. The difference in the magnetic gradients created by teeth and valleys allows the devices to generate a digital output signal that is representative of the target features. will be output opposite valley features). The LT option sets VOUT low when a tooth is opposite the device, and the HT option sets VOUT high when a target tooth is opposite the device. This polarity assignment applies throughout device operation. This ease of use reduces design time and incremental assembly costs for most applications. Valley Internal Electronics This device contains a self-calibrating Hall effect IC that includes a Hall element, a temperature compensated amplifier, and offset cancellation circuitry. The IC also contains a voltage regulator that provides supply noise rejection over the operating voltage range. The Hall transducers and the electronics are integrated on the same silicon substrate by a proprietary BiCMOS process. Changes in temperature do not greatly affect this device, due to the stable amplifier design and the offset rejection circuitry. The Hall IC supports a chopper stabilized Hall element that measures the intensity of magnetic gradients and provides an electrical signal that represents the target features. |B| Target Magnetic Profile 0 V+ Processed Input Signal, VPROC 0 LT option (Inverting) Output Switch State On Off On Off On Off On Off Off On Off On Off On VOUT = High Low-B field Hall element Leadframe High-B field Hall IC North Pole Back-Biasing Rare-Earth Pellet Plastic Pole piece (Concentrator) South Pole VOUT = Low HT option (Following) Output Switch State VOUT = High ATS Device Off On VOUT = Low (A) (B) Figure 5. Application cross-section: (A) target tooth opposite device, and (B) target valley opposite device Figure 6. Output Profile Polarity options allow selection of VOUT either inverted (LT option), or in-phase with the target profile (HT option), when electrically connected as in figure 1. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 10 Self-Calibrating TPOS Speed Sensor IC Optimized for Automotive Cam Sensing Applications ATS675LSE AGC is activated during the Initial Calibration stage at each power-on. The device measures the peak-to-peak application magnetic gradient, and then the gain of the sensor IC is adjusted to normalize the internal processed signal, VPROC , to accommodate any input signal amplitude within the specified Operating Magnetic Signal Range, BSIG . AGC is referenced to the internal magnetic baseline. At the end of the Initial Calibration stage, the AGC results are latched and they are not readjusted while the device remains powered-on. Power Supply Protection The ATS675 provides features for protecting the device against power supply aberrations: Undervoltage Lockout When the supply voltage falls below the undervoltage lockout level, VCCUV , the device Output State changes to Off. The device remains in that state until the voltage level is restored to the VCC operating range. Changes in the target magnetic gradient have no effect until that voltage level is restored. This prevents false signals caused by undervoltage conditions from propagating to the output of the sensor IC. Processed Input Signal, VPROC (%) EMC Protection The ATS675 contains an on-chip regulator that operates throughout a wide range of supply voltage levels. For applications using an unregulated power supply, protection against transients may be added externally. For applications using a regulated supply line, EMI and RFI protection may still be required. Contact Allegro for information on EMC specification compliance. CALI CALTPOSRM Running Mode Running mode switchpoints for I option BTPOSHYS TPOS switching level Time Off On Off On VOUT On Figure 7. Calibration mode waveforms. Off Output State for HT option Operating Modes The device provides three operating modes: TPOS, Calibration, and Running. TPOS and Calibration initialize simultaneously at power-on. TPOS generates immediate device output, controlling device switching while the calibration functions are performed. After calibration is complete, normal operation in Running mode begins. TPOS (True Power-On State) Operation After the power-on time, tPO , the device immediately generates an output voltage corresponding to the target feature opposite the device. It does so by comparing the existing level of the application magnetic gradient, BAPP , to the TPOS switching level, an internal threshold used to distinguish a tooth from a valley during TPOS operation (from power-on until the end of the Initial Calibration stage). If BAPP is less than the threshold, that target feature is evaluated as a valley, and if BAPP is greater , the feature is evaluated as a tooth. Calibration Mode Operation At power-on (simultaneous with TPOS operation) Calibration mode begins. Calibration mode is performed in two stages: the Initial Calibration stage, followed immediately by the TPOS to Running Mode Transition stage (see figure 7). After the second calibration stage, Running mode begins immediately. In Calibration mode, the operating range of the application magnetic gradient, BAPP , is detected and evaluated, and then the ATS675 electronics are adapted for optimal output switching. Calibration is performed quickly, without reading the entire target, because the ATS675 applies the internal magnetic baseline. Initial Calibration Stage During the Initial Calibration stage, TPOS operation controls device output switching while calibration starts. In this stage, the peak-detecting DACs acquire the application magnetic signal. Based on those results, the Automatic Gain Control (AGC) feature calculates the normalized Running mode switching range. This period is minimized, so swapping to the Running mode thresholds can occur as quickly as possible. TPOS to Running Mode Transition Stage At the beginning of this stage, TPOS operation terminates, and throughout this stage the device automatically adjusts the output switching levels from the original preset switching level to the Running mode switchpoints. This transition takes place over one tooth, immediately swapping from TPOS to Running mode switchpoints. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 11 Self-Calibrating TPOS Speed Sensor IC Optimized for Automotive Cam Sensing Applications ATS675LSE Running Mode Operation Running mode begins immediately at the end of Calibration mode. During Running mode, switchpoints are established dynamically, based on the sensed application magnetic gradient, BAPP . To determine switchpoints, BAPP is normalized by the AGC feature, and processed to generate the internal processed signal, VPROC . Two peak-detecting DACs track the VPROC waveform, and the output switchpoints are established as percentages of the values held by the two DACs. Because the switchpoints are established dynamically as a percentage of the peak-to-peak signal, the effects of an application baseline shift are minimized. Running Mode Switchpoints The values used to define Running mode switchpoints are cal- culated as a percentage of the peak-to-peak VPROC . As shown in figure 11, this percentage is subtracted from the maximum VPROC value, VPROC(high) , a value corresponding to a minimum air gap, that is, at the most prominent target tooth. On the ATS675LSE, the switchpoints are referenced to approximately 30% of the peak-to-peak magnetic signal. This level closely corresponds to the mechanical target edges, resulting in optimal timing accuracy versus air gap. Running Mode Hysteresis The ATS675LSE uses an internal hysteresis method, switching at a consistent point on both rising and falling edges. When a target anomaly is encountered, the internal hysteresis thresholds provide immunity to false switching, as illustrated in figure 12. Operating Magnetic Signal, BSIG Application Magnetic Gradient, BAPP BST BHYS BHYS VPROC(low) Application and internal baseline 100 Processed Input Signal, VPROC (%) VPROC(high) |B| 0 Processed Input Signal, VPROC (%) Target Mechanical Profile VPROC(high) BST +BHYS(int) Switchpoints Level -BHYS(int) VPROC(low) On Off On Off Time Output State for LT option 0 Time Figure 11. Switchpoints Level for Running Mode definition (switchpoints indicated by circles). Figure 12. Running mode switching on anomalous peak (switchpoints indicated by circles). Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 12 ATS675LSE Self-Calibrating TPOS Speed Sensor IC Optimized for Automotive Cam Sensing Applications Power Derating The device must be operated below the maximum junction temperature of the device, TJ(max). Under certain combinations of peak conditions, reliable operation may require derating supplied power or improving the heat dissipation properties of the application. This section presents a procedure for correlating factors affecting operating TJ. (Thermal data is also available on the Allegro MicroSystems website.) The Package Thermal Resistance, RJA, is a figure of merit summarizing the ability of the application and the device to dissipate heat from the junction (die), through all paths to the ambient air. Its primary component is the Effective Thermal Conductivity, K, of the printed circuit board, including adjacent devices and traces. Radiation from the die through the device case, RJC, is relatively small component of RJA. Ambient air temperature, TA, and air motion are significant external factors, damped by overmolding. The effect of varying power levels (Power Dissipation, PD), can be estimated. The following formulas represent the fundamental relationships used to estimate TJ, at PD. PD = VIN x IIN (1) T = PD x RJA (2) TJ = TA + T (3) For example, given common conditions such as: TA= 25C, VCC = 12 V, ICC = 7 mA, and RJA = 77 C/W, then: Example: Reliability for VCC at TA = 150C. Observe the worst-case ratings for the device, specifically: RJA = 101 C/W, TJ(max) = 165C, VCC(max) = 24 V, and ICC(max) = 10 mA. Calculate the maximum allowable power level, PD(max). First, invert equation 3: T(max) = TJ(max) - TA = 165 C - 150 C = 15 C This provides the allowable increase to TJ resulting from internal power dissipation. Then, invert equation 2: PD(max) = T(max) / RJA = 15C / 101 C/W = 148.5 mW Finally, invert equation 1 with respect to voltage: VCC(est) = PD(max) / ICC(max) = 148.5 mW / 10 mA = 14.9 V The result indicates that, at TA, the application and device can dissipate adequate amounts of heat at voltages VCC(est). Compare VCC(est) to VCC(max). If VCC(est) VCC(max), then reliable operation between VCC(est) and VCC(max) requires enhanced RJA. If VCC(est) VCC(max), then operation between VCC(est) and VCC(max) is reliable under these conditions. PD = VCC x ICC = 12 V x 7 mA = 84 mW T = PD x RJA = 84 mW x 77 C/W = 6.5C TJ = TA + T = 25C + 6.5C = 31.5C A worst-case estimate, PD(max), represents the maximum allowable power level, without exceeding TJ(max), at a selected RJA and TA. Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 13 Self-Calibrating TPOS Speed Sensor IC Optimized for Automotive Cam Sensing Applications ATS675LSE Package SE 4-Pin SIP 7.000.05 B E 10.000.05 LLLLLLL NNN YYWW 3.30.1 F Branded Face D A 4.90.1 1 6.230.10 2 3 Standard Branding Reference View = Supplier emblem L = Lot identifier N = Last three numbers of device part number Y = Last two digits of year of manufacture W = Week of manufacture 1.30.1 4 0.90.1 +0.06 0.38 -0.04 24.650.10 0.600.10 For Reference Only, not for tooling use (reference DWG-9001) Dimensions in millimeters A Dambar removal protrusion (16X) 11.600.10 B Metallic protrusion, electrically connected to pin 4 and substrate (both sides) 1.0 REF C Thermoplastic Molded Lead Bar for alignment during shipment D Branding scale and appearance at supplier discretion 2.000.10 E Active Area Depth, 0.43 mm F Hall element (not to scale) 1.0 REF A 1.600.10 C 1.270.10 0.710.10 0.710.10 5.500.10 Copyright (c)2008-2013, Allegro MicroSystems, LLC Allegro MicroSystems, LLC reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the information being relied upon is current. Allegro's products are not to be used in life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the failure of that life support device or system, or to affect the safety or effectiveness of that device or system. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, LLC assumes no responsibility for its use; nor for any infringement of patents or other rights of third parties which may result from its use. For the latest version of this document, visit our website: www.allegromicro.com Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 14