A1698 Two-Wire, True Zero-Speed, High Accuracy Sensor IC with Speed and Direction Output FEATURES AND BENEFITS DESCRIPTION • Integrated capacitor for EMC suppression in a single overmolded miniature package • Wide leads facilitate ease of assembly • True zero-speed operation • Pulse-width output protocol • Automatic Gain Control (AGC) for air gap independent switchpoints • Automatic Offset Adjustment (AOA) for signal processing optimization, providing large operating air gap range • Single chip sensing IC for high reliability • Fully synchronous digital logic with Scan and IDDQ testing The A1698 is a Hall-effect-based integrated circuit (IC) that provides a user-friendly solution for two-wire speed sensing of ring magnets or ferrous targets (when back-biased by the user) down to zero-speed in applications where speed and direction is required. The A1698 is offered in the UB package, which integrates the IC and a high temperature ceramic capacitor in a single overmolded SIP package. The integrated capacitor provides enhanced EMC performance. The integrated circuit incorporates Hall-effect circuits and signal processing that switches in response to differential magnetic signals created by magnetic encoders, or, when properly backbiased with a magnet, from ferromagnetic targets. The circuitry contains a sophisticated digital circuit that reduces magnet and system offsets, calibrates the gain for air gap independent switchpoints, and provides true zero-speed operation. Package: 2-pin SIP (suffix UB) The regulated current output is configured for two-wire interface circuitry and is ideally suited for obtaining speed and direction information in wheel speed applications. The 2-pin SIP package is lead (Pb) free, with tin leadframe plating. Not to scale 1 SUPPLY Internal Regulator Offset Adjust Gain Adjust Amp Filter ADC Digital Controller Chopper Stabilization Amp Filter Output Control ADC GROUND 2 Offset Adjust Gain Adjust Functional Block Diagram A1698-DS, Rev. 2 Two-Wire, True Zero-Speed, High Accuracy Sensor IC with Speed and Direction Output A1698 SELECTION GUIDE Part Number Temperature Coefficient Air Gap Warning and Standstill Function A1698LUBTN-FWPE-T Ring Magnet Yes A1698LUBTN-FWPG-T Back-Biased Yes A1698LUBTN-FWBE-T Ring Magnet No A1698LUBTN-FWBG-T Back-Biased No Configuration Options A1698 L UB TN- -T Leadframe Plating Temperature Coefficient: E – Ring magnet (0.2%/ºC typ.) or G – Back-biased Standstill Pulses: B – Blanked, no output during Standstill, or P – Pulses during Standstill with Warning Pulses Pulse Widths: N – Forward = 45 µs (narrow) or W – Forward = 90 µs (wide) Rotation Direction: F – Pin 1 to pin 2 forward or R – Pin 2 to pin 1 forward Instructions (Packing) TN – Tape and reel Package Designation UB – 2-pin plastic SIP Operating Temperature Range: L Allegro Identifier and Device Type A1698 Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 2 Two-Wire, True Zero-Speed, High Accuracy Sensor IC with Speed and Direction Output A1698 SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS Characteristic Symbol Notes Rating Unit Supply Voltage VCC 28 V Reverse Supply Voltage VRCC –18 V Operating Ambient Temperature TA –40 to 150 °C Maximum Junction Temperature TJ(max) 165 °C Tstg –65 to 170 °C Storage Temperature L temperature range Terminal List Table 1 Name Number Function VCC 1 Supply Voltage GND 2 Ground 2 UB Package, 2-Pin SIP Pinout Diagram INTERNAL DISCRETE CAPACITOR RATINGS Characteristic Nominal Capacitance Symbol CSUPPLY Test Conditions Connected between VCC and GND Value (Typ.) Unit 2200 pF Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 3 Two-Wire, True Zero-Speed, High Accuracy Sensor IC with Speed and Direction Output A1698 OPERATING CHARACTERISTICS: Valid throughout full operating and temperature ranges, unless otherwise specified Characteristic Symbol Test Conditions Min. Typ.1 Max. Unit ELECTRICAL CHARACTERISTICS Supply Voltage 2 VCC Operating, TJ < TJ(max) 4 – 24 V Reverse Supply Current 3 IRCC VCC = VRCC(max) – – –10 mA VZsupply ICC = ICC(max) + 3 mA, TA = 25°C 28 – – V ICC(LOW) Low-current state 5.9 7 8.4 mA ICC(HIGH) High-current state 12 14 16 mA ICC(HIGH) / ICC(LOW) Measured as ratio of high current to low current (isothermal) 1.9 – – – Signal stabilization time from VCC > undervoltage lockout level – – 1 ms tr, tf Voltage measured at terminal 2 in Figure 1, RL = 100 Ω, CL = 10 pF, measured between 10% and 90% of signal. 0 – 1.5 μs Operate Point BOP % of peak-to-peak IC-processed magnetic signal – 60 – % Release Point BRP % of peak-to-peak IC-processed magnetic signal – 40 – % 0 – 5 kHz 20 – 1200 G – 2× BSIG(MIN) – G –300 – 300 G – +0.2 – %/°C Supply Zener Clamp Voltage OUTPUT Power-On State Supply Current Supply Current Ratio ICC(LOW) Supply Current Stabilization Time Output Rise/Fall Time – OPERATING CHARACTERISTICS Operating Frequency Input Signal f BSIG Differential signal, measured peak to peak Air Gap Warning BWARN -P variant Allowable User-Induced Differential Offset BSIGEXT External differential signal bias (DC), operating within specification Sensitivity Temperature Coefficient 5 TC Total Pitch Deviation Valid for full temperature range E variant, Ring Magnet G variant, Back-Biased For constant BSIG, sine wave Front-End Chopping Frequency – TBD – %/°C – – +/-2 % – 340 – kHz OUTPUT PULSE CHARACTERISTICS, PULSE PROTOCOL4 Pulse Width Off Time tw(Pre) Pulse Width, Air Gap Warning tw(Warn) Pulse Width, Forward Rotation tw(FWD) 38 45 52 μs -P variant 38 45 52 μs -N variant 38 45 52 μs -W variant 76 90 104 μs -N variant 76 90 104 μs Pulse Width, Reverse Rotation tw(REV) -W variant 153 180 207 μs Pulse Width, Standstill tw(STOP) -P variant 1232 1440 1656 μs TSTOP -P variant 590 737 848 ms Standstill Period 1 Typical values are at TA = 25°C 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 representative discussions in Power Derating section. 3 Negative current is defined as conventional current coming out of (sourced from) the specified device terminal. 4 Load circuit is R = 100 Ω and C = 10 pF. Pulse duration measured at threshold of ( (I L L CC(HIGH) + ICC(LOW)) /2). 5 Ring magnet decreases strength with rising temperature. Device compensates. Note that B SIG requirement is not influenced by this. 2 Maximum Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 4 Two-Wire, True Zero-Speed, High Accuracy Sensor IC with Speed and Direction Output A1698 VSUPPLY 1 A1698 CSUPPLY 2 RL 100 Ω CL Figure 1: Typical Application Circuit BSEQ(n) BSEQ(n+1) Target S N S N TTARGET VPROC TVPROC VPROC = the processed analog signal of the sinusoidal magnetic input (per channel) TTARGET = the period between successive sensed target magnetic edges of the same polarity (either both north-to-south or both south-to-north) Figure 2: Differential Signal Variation Figure 3: Definition of TTARGET Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 5 Two-Wire, True Zero-Speed, High Accuracy Sensor IC with Speed and Direction Output A1698 THERMAL CHARACTERISTICS Characteristic Symbol Package Thermal Resistance RθJA Test Conditions* Single-layer PCB with copper limited to solder pads Value Unit 213 °C/W *Additional thermal information is available on the Allegro website. Maximum Allowable VCC (V) Power Derating Curve 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 VCC(max) VCC(min) 20 40 60 80 100 120 140 160 180 Temperature (ºC) 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 20 40 60 80 100 120 140 160 180 Temperature (ºC) Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 6 Two-Wire, True Zero-Speed, High Accuracy Sensor IC with Speed and Direction Output A1698 CHARACTERISTIC PLOTS 8.4 16.0 VCC: 24 V VCC: 24 V 15.0 7.4 ICC (mA) ICC (mA) 7.9 VCC: 24 V 15.5 VCC: 24 V 6.9 14.5 14.0 13.5 13.0 6.4 12.5 5.9 12.0 -50 0 50 100 -50 150 0 TA (ºC) 50 100 150 TA (ºC) Supply Current versus Ambient Temperature Supply Current versus Ambient Temperature 104 207 tW(FWD), -W Variant 100 tW(FWD), -W Variant 201 Pulse Width (µs) Pulse Width (µs) 195 96 92 88 84 189 183 177 171 165 80 159 76 153 -50 0 50 100 150 TA (ºC) Output Pulse Widths versus Ambient Temperature -50 0 50 100 150 TA (ºC) Output Pulse Widths versus Ambient Temperature Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 7 Two-Wire, True Zero-Speed, High Accuracy Sensor IC with Speed and Direction Output A1698 FUNCTIONAL DESCRIPTION The sensor IC contains a single-chip Hall-effect circuit that supports a trio of Hall elements. These elements are used in differential pairs to provide electrical signals containing information regarding edge position and direction of target rotation. The A1698 is intended for use with ring magnet targets, or, when back-biased with an appropriate magnet, with ferromagnetic targets (gears). The IC detects the peaks of the magnetic signals and sets dynamic thresholds based on these detected signals. Data Protocol Description When a target passes in front of the device (opposite the branded face of the package case), the A1698 generates an output pulse for each magnetic pole, or each tooth and valley, of the target. Speed information is provided by the output pulse rate, while direction of target rotation is provided by the duration of the output pulses. The sensor IC can sense target movement in both the forward and reverse directions. The translation of magnetic input to the output is shown in Figure 6. FORWARD ROTATION For the –F variant, when the target is rotating such that a target feature passes from pin 1 to pin 2, this is referred to as forward Rotating Target (Ring magnet or ferromagnetic) rotation. This direction of rotation is indicated on the output by a tW(FWD) pulse width. For the –R variant, forward direction is indicated for target rotation from pin 2 to 1 (see Figure 4). REVERSE ROTATION For the –F variant, when the target is rotating such that a target feature passes from pin 2 to pin 1, this is referred to as reverse rotation. This direction of rotation is indicated on the output by a tW(REV) pulse width. For the –R variant, reverse direction is indicated for target rotation from pin 1 to 2. Output edges are triggered by VPROC transitions through the switchpoints. On a crossing, the output is first set to ICC(LOW) for a duration of tw(PRE), after which the output pulse of ICC(HIGH) is present for tw(FWD) or tw(REV). The IC is always capable of properly detecting input signals up to the defined operating frequency. However, the end user will note that a sequence of tw(PRE) and tw(REV) does meet this frequency. The tw(PRE) period is dominant, thus always providing rising output edge, but, at high frequencies, potentially truncating the ICC(HIGH) duration. Branded Face of Package S N S N S SN N N Pin 1 S Pin 2 Rotation from pin 1 to pin 2 Branded Face of Package Rotating Target (Ring magnet or ferromagnetic) S N S N S S N Pin 1 ICC(HIGH) tw(FWD) tw(FWD) N tw(Pre) Pin 2 tw(Pre) ICC(LOW) Rotation from pin 2 to pin 1 Figure 4: Target Orientation Relative to Device (ring magnet shown). Figure 5: Output Timing Example Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 8 Two-Wire, True Zero-Speed, High Accuracy Sensor IC with Speed and Direction Output A1698 Package Case Branded Face Device Orientation to Target Package Case Branded Face (Pin 2 Side) IC (Pin 1 Side) Device Orientation to Target (Top View of Package Case) (Pin 2 Side) Back-Biasing Magnet IC (Pin 1 Side) (Top View of Package Case) South Pole North Pole Mechanical Position (Target moves past device pin 1 to pin 2) Target (Radial Ring Magnet) This pole sensed earlier S N This pole sensed later S Target Magnetic Profile Speed Channel Element Pitch +B Mechanical Position (Target moves past device pin 1 to pin 2) Target (Gear) This tooth sensed earlier This tooth sensed later Target Magnetic Profile Speed Channel Element Pitch +B –B IC Internal Differential Analog Signals, VPROC BRP Speed Channel IC Internal Differential Analog Signals, VPROC BRP Speed Channel BOP BOP Direction Channel BRP Direction Channel BRP BOP Detected Channel Switching BOP Detected Channel Switching Channel A Channel A Channel B Channel B Output (pulse protocol) Output (pulse protocol) Figure 6: Basic Operation Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 9 Two-Wire, True Zero-Speed, High Accuracy Sensor IC with Speed and Direction Output A1698 Calibration and Direction Validation When power is applied to the A1698, the sensor IC internally detects the profile of the target. The gain and offset of the detected signals are adjusted during the calibration period, normalizing the internal signal amplitude for the installation air gap of the device. The Automatic Gain Control (AGC) feature ensures that operational characteristics are isolated from the effects of installation air gap variation. Automatic Offset Adjustment (AOA) is circuitry that compensates for the effects of chip, magnet, and installation offsets. This circuitry works with the AGC during calibration to adjust VPROC in the internal A-to-D range to allow for acquisition of signal peaks. AOA and AGC function separately on the two differential signal channels. During calibration, output pulses with direction information are immediately transmitted to the output. Depending on target design, air gap, and the phase of the target, direction may be momentarily incorrect. Following a direction change in running mode, direction changes are immediately transmitted to the output. Depending on target design and the phase of the target, direction may be fleetingly incorrect. Target Rotation N S N S N S N S N Target Differential Magnetic Profile tW(FWD) or tW(REV) tW(FWD) or tW(REV) Opposite North Pole Opposite N→S Boundary ICC Opposite South Pole Opposite S→N Boundary tW(FWD) tW(FWD) tW(FWD) t Device Location at Power-On Figure 7: Startup Position Effect on First Device Output Switching Normal Target Rotation N S Normal Target Rotation Vibration N S N S N S N S Target Differential Magnetic Profile tW(REV) tW(FWD) tW(FWD) [or tW(REV)] [or tW(REV)] [or tW(FWD)] tW(FWD) / tW(REV) tW(FWD) tW(FWD) [or tW(REV)] [or tW(REV)] Figure 8: Output Functionality in the Presence of Running Mode Target Vibration Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 10 Two-Wire, True Zero-Speed, High Accuracy Sensor IC with Speed and Direction Output A1698 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 (RθJA) 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 (RθJC ) is relatively small component of RθJA. Ambient air temperature (TA ) and air motion are significant external factors, damped by overmolding. The effect of varying power levels (Power Dissipation or PD), can be estimated. The following formulas represent the fundamental relationships used to estimate TJ, at PD. A worst-case estimate, PD(max), represents the maximum allowable power level (VCC(max), ICC(max)), without exceeding TJ(max), at a selected RθJA and TA. Example: Reliability for VCC at TA = 150°C, package UB, using minimum-K PCB. Observe the worst-case ratings for the device, specifically: RθJA = 213°C/W, TJ(max) = 165°C, VCC(max) = 24 V, and ICC(AVG) = 14.66 mA. ICC(AVG) is computed using ICC(HIGH)(max) and ICC(LOW)(max), with a duty cycle of 73% computed from tw(REV)(max) on-time and tw(FW)(min) off-time (pulse width protocol). This condition happens at a select limiting frequency. Calculate the maximum allowable power level (PD(max) ). First, invert equation 3: ΔTmax = 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) = ΔTmax ÷ RθJA = 15°C ÷ 213 °C/W = 70.4 mW PD = VIN × IIN (1) ΔT = PD × RθJA (2) VCC(est) = PD(max) ÷ ICC(AVG) = 70.4 mW ÷ 14.6 mA = 4.8 V TJ = TA + ΔT (3) The result indicates that, at TA, the application and device can dissipate adequate amounts of heat at voltages ≤VCC(est). For example, given common conditions such as: TA= 25°C, VCC = 12 V, ICC = 14 mA, and RθJA = 213 °C/W, then: PD = VCC × ICC = 12 V × 7 mA = 84 mW ΔT = PD × RθJA = 84 mW × 213 °C/W = 17.9°C Finally, invert equation 1 with respect to voltage: Compare VCC(est) to VCC(max). If VCC(est) ≤ VCC(max), then reliable operation between VCC(est) and VCC(max) requires enhanced RθJA. If VCC(est) ≥ VCC(max), then operation between VCC(est) and VCC(max) is reliable under these conditions. TJ = TA + ΔT = 25°C + 17.9°C = 42.9°C Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 11 Two-Wire, True Zero-Speed, High Accuracy Sensor IC with Speed and Direction Output A1698 PACKAGE OUTLINE DRAWING For Reference Only – Not for Tooling Use (Reference DWG-9070) Dimensions in millimeters – NOT TO SCALE Dimensions exclusive of mold flash, gate burs, and dambar protrusions Exact case and lead configuration at supplier discretion within limits shown 4.00 ±0.05 B 4X10° E 1.45 1.50 ±0.10 1.45 E C 0.55 E 1.41 E 4.00 ±0.05 E E1 Mold Ejector Pin Indent E3 E E2 E A 4 X 2.50 REF 0.25 REF 0.30 REF 45° Branded Face NNN YYWW LLLL 0.85 ±0.05 0.42 ±0.10 2.54 REF 4 X 0.85 REF D Standard Branding Reference View 1 N Y W L 2 1.00 ±0.10 = Supplier emblem = Last three digits of device part number = Last 2 digits of year of manufacture = Week of manufacture = Lot number 12.20 ±0.10 4 X 7.37 REF +0.05 0.25 –0.03 1.80 REF A Dambar removal protrusion (8×) B Gate and tie burr area C Active Area Depth, 0.38 mm REF 0.38 REF D Branding scale and appearance at supplier discretion 0.25 REF 4 X 0.85 REF E Hall elements (E1, E2, and E3); not to scale 0.85 ±0.05 F Molded Lead Bar for preventing damage to leads during shipment 1.80 ±0.05 F 4.00 ±0.05 1.50 ±0.10 Figure 9: Package UB, 2-Pin SIP Allegro MicroSystems, LLC 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000; www.allegromicro.com 12 Two-Wire, True Zero-Speed, High Accuracy Sensor IC with Speed and Direction Output A1698 Revision History Revision Current Revision Date – March 24, 2015 1 May 6, 2015 2 March 2, 2016 Description of Revision Initial release. Corrected typo in Selection Guide. Updated Package Outline Drawing molded lead bar footnote, Internal Discrete Capacitor Ratings table, and miscellaneous editorial changes. Copyright ©2016, 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 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, 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 13