HEDS-974x Series For 180, 300, 360 LPI Small Optical Encoder Modules Data Sheet Description The HEDS-974x series is a high performance, low cost, optical incremental encoder module. When operated in conjunction with codestrip, this module detects linear position. The module consists of a lensed LED source and a detector IC enclosed in a small C-shaped plastic package. Due to a highly collimated light source and a unique photodetector array, the module is extremely tolerant to mounting misalignment. The two-channel digital outputs and 5 V supply input are accessed through four solder-plated leads located on 2.54 mm (0.1 inch) centers. Applications The HEDS-974x provides sophisticated motion detection at a low cost, making close-loop control very costcompetitive! Typical applications include printers, plotters, copiers, and office automation equipment. This IC consists of multiple sets of photodetectors and the signal processing circuitry necessary to produce the digital waveforms. The codestrip moves between the emitter and detector, causing the light beam to be interrupted by the pattern of spaces and bars on the codestrip. The photodiodes which detect these interruptions are arranged in a pattern that corresponds to the count density of the codestrip. These detectors are also spaced such that a light period on one pair of detectors corresponds to a dark period on the adjacent pair of detectors. The photodiode outputs are fed through the signal processing circuitry. Two comparators receive these signals and produce the final outputs for channels A and B. Due to this integrated phasing technique, the digital output of channel A is in quadrature with channel B (90 degrees out of phase). Features Note: Agilent Technologies encoders are not recommended for use in safety critical applications. Eg. ABS braking systems, power steering, life support systems and critical care medical equipment. Please contact sales representative if more clarification is needed. Theory of Operation The HEDS-974x is a C-shaped emitter/detector module. Coupled with a codewheel, it translates rotary motion into a two-channel digital output. Coupled with a codestrip, it translates linear motion into digital outputs. As seen in the block diagram, the module contains a single Light Emitting Diode (LED) as its light source. The light is collimated into a parallel beam by means of a single lens located directly over the LED. Opposite the emitter is the integrated detector circuit. • • • • • • • • • • • • • Small size Multiple mounting options Wide resolution range Linear options available No signal adjustment required Insensitive to radial and axial play –40°C to +85°C operating temperature High resolution version of the HEDS-970x Two-channel quadrature output TTL or 5.0 V CMOS compatible Single 5 V supply Wave solderable Integrated 2.5 K Ω pullup on outputs ESD WARNING: NORMAL PRECAUTIONS SHOULD BE TAKEN TO AVOID STATIC DISCHARGE. Definitions Count (N) = the number of bar and window pairs or Counts Per Revolution (CPR) of the codewheel, or the number of Lines Per Inch (LPI) of the codestrip. State Width (S): The number of electrical degrees between a transition in the output of channel A and the neighboring transition in the output of channel B. There are four states per cycle, each nominally 90°e. 1 Shaft Rotation = 360 mechanical degrees = N cycles State Width Error (∆S): The deviation, in electrical degrees, of each state width from its ideal value of 90°e. 1 Cycle (c) = 360 electrical degrees (°e) = 1 bar and window pair Pulse Width (P): The number of electrical degrees that an output is high during one cycle. This value is nominally 180°e or 1/2 cycle. Phase (φ): The number of electrical degrees between the center of the high state of channel A and the center of the high state of channel B. This value is nominally 90°e for quadrature output. Phase Error (∆φ): The deviation of the phase from its ideal value of 90°e. Pulse Width Error (∆P): The deviation, in electrical degrees, of the pulse width from its ideal value of 180°e. Direction of Rotation: When the codewheel rotates counterclockwise, as viewed looking down on the module (so the marking is visible), channel A will lead channel B. If the codewheel rotates in the opposite direction, channel B will lead channel A. Optical Radius (ROP): The distance from the codewheel’s center of rotation to the optical center (OC) of the encoder module. Angular Misalignment Error (EA): Angular misalignment of the sensor in relation to the tangential direction. This applies for both rotary and linear motion. Mounting Position (RM): Distance from motor shaft center of rotation to center of alignment tab receiving hole. Absolute Maximum Ratings Parameter Symbol Min. Max. Units Storage Temperature TS –40 85 °C Operating Temperature TA –40 85 °C Supply Voltage VCC –0.5 7 V Output Voltage VO –0.5 VCC V Output Current per Channel IO –1.0 5 mA 260 °C Soldering Temperature 2 Notes t ≤ 5 sec. Recommended Operating Conditions Parameter Symbol Min. Temperature T –40 Supply Voltage VCC 4.5 Load Capacitance CL Pullup Resistor RL Typ. 5.0 Units 85 °C 5.5 V 100 pF Notes Ripple < 100 mVp-p. Recommended one bypass capacitor (1 µF) between V CC and GND less than 15 cm from the encoder. none Recommended no pullup. Device has integrated 2.5 kΩ on outputs. Count Frequency Angular Misalignment EA Max. –2.0 0 40 kHz (Velocity (rpm) x N) / 60 +2.0 deg. Mounting considerations. Electrical Characteristics over Recommended Operating Range, Typical at TA = 25˚C Parameter Symbol Min. Typ. Max. Units Supply Current ICC 12 21 40 mA High Level Output Voltage VOH 2.4 Low Level Output Voltage VOL Rise Time tr Fall Time tf Notes V IOH = –200 µA V IOL = 3.2 mA 70 ns CL = 25 pF 45 ns RL = (NO pullup) 0.4 Encoding Characteristics Encoding Characteristics over Recommended Operating Range and Recommended Mounting Tolerances. These characteristics do not include codewheel/codestrip contribution. The Typical Values are averages over the full rotation of the codewheel. Parameter Symbol Typical Maximum Units Pulse Width Error ∆P 5 40 °e Logic State Width Error ∆S 3 40 °e Phase Error ∆φ 2 15 °e 3 Recommended Codewheel and Codestrip Characteristics Parameter Window/Bar Ratio Center of Post to Inside Edge of Window Center of Post to Outside Edge of Window Center of Post to Inside Edge of Codestrip Symbol Ww/Wb W1 W2 L Min. 0.7 1.04 (0.041) 0.76 (0.030) Max. 1.4 3.60 (0.142) Units Notes mm (inch) mm (inch) mm (inch) Mounting Considerations 4.44 ± 0.13 0.175 ± 0.005 Rm IMAGE SIDE OF CODEWHEEL/CODESTRIP EA For linear motion, angular misalignment, EA, must be ≤ ± 2 degrees to achieve Encoding Characteristics. All dimensions for mounting the module and codestrip should be measured with respect to the two mounting posts, shown above. Recommended Screw Size: M2.5 x 0.45 or 2-56 4 Recommended Wave Solder Conditions Flux – RMA Water Soluble (per MIL-F-14256D) Process Parameters 1. Flux 2. Pre-heat 60 seconds total Nominal preheat temp: 90°C Min: 85°C Max: 110°C 3. Solder Pot Zone Nominal dip in time: 2.5 - 4.5 seconds Min: 2.5 seconds Max: 5 seconds PCB top side: 140 -160°C PCB bottom side: 240 - 260°C 4. Wave Solder 255°C, 1.2 meters/minute line speed 5. Hot Water Wash 1st: 30°C 45 seconds 2nd: 70°C 90 seconds 6. Rinse 1st: 23°C 45 seconds 2nd: 23°C 45 seconds 7. Dry 1st: 80°C 105 seconds 2nd: 95°C 105 seconds Ordering Information HEDS-974 Option Lead Bend 0 – Straight Leads 1 – Bend Leads HEDS-9740 Q 2 1 Q 2 1 HEDS-9741 Resolution Options Q – 180 LPI, linear 2 – 300 LPI, linear 1 – 360 LPI, linear Mounting Options 50 – Standard 50 * * * 54 51 52 53 55 * Package Dimensions Mounting Option #50 LEAD THICKNESS = 0.25 mm LEAD PITCH = 2.54 mm 3.8 GND 3.0 CH A R 1.4 VCC CH B 10.8 ± 0.7 0.50 R 2.6 5.5 ± 0.4 PIN 1 ID 3.9 0.14 (OPTICAL CENTER) 0.8 2x ∅ 2.00 ± 0.03 8.4 1.70 ± 0.22 4.2 7.5 PART # 12.6 ± 0.7 DATE CODE C = COUNTRY OF ORIGIN 10.1 20.2 ± 0.7 1.8 9.8 5 7.0 15.0 3.90 ± 0.15 Note: If not specified, tolerances are xx. ± 0.7, xx.x ± 0.3, xx.xx ± 0.07 mm. YYWW 4.2 C 5.0 X AGILENT 1.4 6.40 XXXXX 8.7 50 OPTION CODE For product information and a complete list of distributors, please go to our website: www.avagotech.com Avago, Avago Technologies, and the A logo are trademarks of Avago Technologies Limited in the United States and other countries. Data subject to change. Copyright © 2008 Avago Technologies Limited. All rights reserved. Obsoletes 5988-6067 5988-8042EN January 23, 2008