aedt-9140 series high temperature 115 c three channel optical incremental encoder modules 100 cpr to 1000 cpr data sheet description the aedt-9140 series are three channel optical incremen- tal encoder modules. when used with a codewheel, these low cost modules detect rotary position. each module consists of a lensed led source and a detector ic enclosed in a small plastic package. due to a highly collimated light source and a unique photodetector array, these modules are extremely tolerant to mounting misalignment. the aedt-9140 has two channel quadrature outputs plus a third channel index output. this index output is a 90 electrical degree high true index pulse which is generated once for each full rotation of the codewheel. the aedt-9140 optical encoder is designed for use with a codewheel which has an optical radius of 11.00 mm (0.433 inch) for 100 cpr to 1000 cpr and 11.68 mm (0.460 inch) for 1000 cpr. the quadrature signals and the index pulse are accessed through ?ve 0.46 mm square pins located on 1.27 mm (pitch) centers. features two channel quadrature output with index pulse resolution from 100 cpr to 1000 cpr (cycles per revolution) low cost easy to mount no signal adjustment required small size -40 c to 115 c operating temperature ttl compatible single 5v supply applications typical applications include: printers plotters tape drives machine tools industrial and factory automation equipment. note: avago technologies encoders are not recommended for use in safety critical applications. eg. abs braking systems, power steering, life support systems and critical care medical.
2 theory of operation the aedt-9140 is an emitter/detector module. coupled with a codewheel, these modules translates rotary motion of a shaft into a three-channel digital output. as seen in figure 1, the modules contain a single light emitting diode (led) as its light source. the light is col- limated into a parallel beam by means of a single poly- carbonate lens located directly over the led. opposite the emitter is the integrated detector circuit. this ic consists of multiple sets of photodetectors and the signal process- ing circuitry necessary to produce the digital waveforms. the codewheel rotates between the emitter and detector, causing the light beam to be interrupted by the pattern of spaces and bars on the codewheel. the photodiodes which detect these interruptions are arranged in a pattern that corresponds to the radius and design of the code-wheel. these detectors are also spaced such that a light period on one pair of detectors corre- sponds to a dark period on the adjacent pair of detectors. the photodiode outputs are then fed through the signal processing circuitry resulting in a, a-bar, b, b-bar, i and i- bar. comparators receive these signals and produce the ?nal output for channels a and b. due to this integrated phasing technique, the digital output of channel a is in quadrature with that of channel b (90 degrees out of phase). de?nitions note: refer to figure 2 cycles (n): the number of electrical cycles per revolution (cpr). note: cpr refers to the raw signal from encoder, that is the cycles before 4x decode. one cycle (c): 360 electrical degrees ( e). one shaft rotation: 360 mechanical degrees, n cycles. cycle error ( c): an indication of cycle uniformity. the di?er- ence between an observed shaft angle which gives rise to one electrical cycle, and the nominal angular increment of 1/n of a revolution. pulse width (s): the number of electrical degrees that an output is high during 1 cycle. this value is nominally 180e or 1/2 cycle. pulse width error ( p): the deviation, in electrical degrees, of the pulse width from its ideal value of 180e. 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 4 states per cycle, each nominally 90e. state width error ( s): the deviation, in electrical degrees, of each state width from its ideal value of 90e. phase error ( ): the deviation of the phase from its ideal value of 90e. direction of rotation: when the codewheel rotates in the clockwise direction viewing from top of the module (di- rection from v to g), 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 codewheels cen- ter of rotation to the optical center (o.c) of the encoder module. index pulse width (po): the number of electrical degrees that an index is high during one full shaft rotation. this value is nominally 90 e or 1/4 cycle.
3 block diagram output waveforms figure 1. figure 2. a b i a b i signal proce ssing circuitry comparators photo diodes lens led resistor emitter section detector section code wheel v cc ch. a ch. b ch. i gnd index processing circuitry
4 aedt-9140 technical speci?cations absolute maximum ratings parameter symbol min. max. units notes storage temperature t s -40 115 c operating temperature t a -40 115 c supply voltage v cc -0.5 7 volts output voltage v o -0.5 v cc volts output current per channel, iout i out -1.0 18 ma recommended operating conditions parameter symbol min. typ. max. units notes temperature t a -40 115 c supply voltage v cc 4.5 5.0 5.5 volts ripple < 100mvp-p load capacitance c l 100 pf 2.7 k pull-up frequency f 100 khz velocity (rpm) x n/60 shaft perpendicularity plus axial play 0.20 ( 0.008) mm (in.) refer to mounting consideration shaft eccentricity plus radial play 0.04 (0.0015) mm (in.) refer to mounting consideration electrical characteristics electrical characteristics over recommend operating range, typical at 25 c. parameter symbol min. typ max. units notes supply current i cc 30 57 85 ma high level output voltage v oh 2.4 v typ. i oh = -0.5 ma low level output voltage v ol 0.4 v typ. i ol = 10 ma rise time t r 180 ns c l = 25 pf r l = 2.7 k pull-up fall time t f 50 ns note: typical values speci?ed at vcc = 5.0 v and 25 c
5 encoding characteristics aedt-9140 (except C b0b) encoding characteristics over the recommended opera ting conditions and recommended mounting tolerances unless otherwise speci?ed. parameter symbol min. typ. max. units cycle error ? c 315e pulse width error ? p 730e logic state width error ? s 530e phase error ? 215e position error ? 10 40 min. of arc index pulse width p o 60 90 120 e ch i rise after ch b or ch a fall -40c to + 115c t 1 10 100 1000 ns ch i rise after ch a or ch b rise -40c to + 115c t 2 10 300 1000 ns encoding characteristics aedt-9140-b0b & aedt-9140-b00 encoding characteristics over the recommended opera ting conditions and recommended mounting tolerances unless otherwise speci?ed. parameter symbol min. typ. max. units cycle error - b0b option - b00 option ? c 3 6 15 20 e pulse width error ? p 750e logic state width error ? s 550e phase error ? 215e position error ? 10 40 min. of arc index pulse width p o 40 90 120 e ch i rise after ch b or ch a fall -40c to + 115c t 1 10 450 1500 ns ch i rise after ch a or ch b rise -40c to + 115c t 2 10 250 1500 ns
6 electrical interface to ensure reliable encoding performance, the aedt-9140 three channel encoder modules require 2.7 k ( 10%) pull-up resistors on output pins 2, 3, and 5 (channels a, i and b) as shown in figure 3. these pull-up resistors should be located as close to the encoder module as possible (within 4 feet). each of the three encoder module outputs can drive a single ttl load in this con?guration. figure 3. customized solutions customization of codewheel cpr is possible. it has to be based on the encoder lpi table given below. part number lpi AEDT-9140-C00 36.7 aedt-9140-e00 73.5 aedt-9140-f00 94 aedt-9140-g00 132.3 aedt-9140-h00 147 aedt-9140-a00 183 aedt-9140-i00 188 aedt-9140-b0b 346 aedt-9140-b00 367.5 cpr calculation formula: cpr = lpi x 2 x x rop 25.4 where: cpr = counts per revolution lpi = encoder lpi provided in the table rop = encoder optical radius in mm * recommended maximum codewheel diameter should not exceed 30mm. note: the customization of the codewheel method is valid from theoreti- cal standpoint. however avago strongly recommends a full character- ization to be done to determine the actual performance of the encoder with customized codewheel. characterization means validating the encoding performance (consist of cycle error, pulse width error, logic state width error, phase error, po- sition error & index pulse width, index channel rise and fall time over the recommended operating conditions and recommended mounting tolerances.
7 mounting considerations rop 12.60 6.30 0.50 artwork codewheel mounting boss 2mm dia. 2 places optical center axis gap typical e g e t e r shaft center axis optical center axis mounting plane r0.89 recommended screw size: m1.6 x 0.35 recommended mounting screw torque : 1 lbin (0.113 nm) note: these dimensions include shaft endplay and codewheel warp. all dimension for mounting the module and codewheel should be measur ed with respect to two mounting boss, as shown above. error rop = 11mm unit notes e g gap 0.20 mm recommend to mount the codewheel closer to the detector side (upper side) for optimum encoder performance. e r radial 0.13 mm e t tangential 0.13 mm
8 package dimension 21.60 13.6 1.6 5.34 2.00 0.80 3.00 4.00 0.46 1.27 4.90 1.78 2.40 13.60 1.60 21.60 1.17 3.00 4.40 2.69 3.69 17.80 3.69 optical center axis optical center axis optical center axis typical dimensions in millimeters front view side view top view r 15.50 r 0.89
for product information and a complete list of distributors, please go to our web site: www.avagotech.com avago, avago technologies, and the a logo are trademarks of avago technologies in the united states and other countries. data subject to change. copyright ? 2005-2009 avago technologies. all rights reserved. av02-1101en - november 10, 2009 ordering information option aedt-9140 resolution options codewheels optical radius c - 00 - 11.00 mm e - - 11.68 mm f - g - h - a - i - b - 256 cpr 1000 cpr 100 cpr 200 cpr 360 cpr 400 cpr 500 cpr 512 cpr 0b
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