Agilent AEAS-7000Plug and Play Ultra-PrecisionAbsolute Encoder 16-bit Gray CodeData Sheet

Description

The encoder IC consists of 13signal photo diode channels and1 monitor photo diode channeland is used for the opticalreading of rotary carriers (i.e.,discs). The photodiodes areaccompanied with precisionamplifiers plus additionalcircuitry.

The monitor channel is used todrive a constant current sourcefor the highly collimated IRillumination system.

Functional Description

Background

The 13 signal channels are set upas:

1. Two precision defining signals(A0, A09), which are two 90°electrical shifted sine, cosinesignals. These signals areconditioned to be compensatedfor offset and gain errors.After conditioning they are onchip interpolated (4 bit) andcomputed to an absolute 6 bitGray code. Additionally, theseSin/Cos signals can be tappedas two true-differential analogoutputs to be used at thesystem designer’s choice.

Features

• Minumum mechanical alignmentduring installation

• 2 Sine/Cosine true differentialoutputs with 1024 periods for unitalignment

• Integrated highly collimatedillumination system

• 11 digital tracks plus 2 sin/costracks generate precise 16 bit Graycode

• Ultra fast, 1 µs cycle for serial dataoutput word equals 16 MHz

• On-chip interpolation and codecorrection to compensate formounting tolerance

• MSB can be inverted for changingthe counting direction

• Internally built in monitor track fortracking the light level

• Watch dog with alarm output

• –25°C to +85°C operating temp.

Applications

• Rotary application up to 16 bit/360° absolute position

• Rotary application up to 11 bit userdefined code patterns

• Cost effective solution for directintegration into OEM systems

2. 11 analog (A1-A11) channelswhich are directly digitizedby precison comparators withhysterisis tracking. Thedigitized signals are calledD1-D11.

An internal correction andsynchronization module allowsthe composition of a true 16 bitgray code by merging the databits of 1) and 2) by still keepingthe code monotony.

There is a Gray code correctionfeature for this encoder tocounter any codewheelimperfection or misalignment.This Gray code correction canbe disabled/enabled by the pinKORR.

The gain and offset conditioningvalue of the sine and cosinewave has been on-chip presetby factory. This willcompensate for mechanicalsensor misalignment error.

2

Signal-Channels A1-A11

The photocurrent of the photodiodes is fed into a trans-impedance amplifier. Theanalog output of the amplifierhas a voltage swing of (dark/light) about 1.3 V. Everyoutput is transformed byprecision comparators intodigital signals (D1-D11). Thethreshold is at VDD/2(=Analog-reference), regulatedby the monitor channel.

Monitor Channel with LED Control atPins LEDR and LERR

The analog output signal of themonitor channel is regulatedby the LED current. Aninternal bipolar transistor setsthis level to VDD/2 (controlvoltage at pin LEDR). Thusthe signal swing of each outputis symmetrical to VDD/2(=Analog-reference)

The error bit at pin LERR istriggered if the Ve of theinternal bipolar transistor islarger than VDD/2.

Signals Channels A0, A09 with SignalConditioning and Self Calibration

These two channels give out asine and cosine wave whichare 90 deg phase shifted.These signals have amplitudeswhich are almost constant dueto the LED current monitoring.Due to amplifier mismatch thesignals do have gain and offseterrors. These errors areeliminated by an adaptivesignal conditioning circuitry.The conditioning values areon-chip preprogrammed byfactory. The analog outputsignals of A0 and A09 aresupplied as true-differentialvoltage with a peak to peakvalue of 2.0 V at the pinsA09P, A09N, A0P, A0N.

Interpolator for Channels A0,A09

The interpolator generates thedigital signals D0,D09 and D-1to D-4. The interpolatedsignals D-1 to D-4 extend the12 bit Gray code of the signalsD11….D0 to form a 16 bit Graycode.

D0 and D09 are digitized fromA0 and A09. The channels A0-A11 and A09 have very highdynamic bandwidth, whichallows a real time monotone 12bit Gray code at 12000 RPM.

The interpolated 16 bit Graycode can be used up to 1000RPM only. At more than 1000RPM, only the 12 bit Gray codefrom the MSB side can beused.

LSB Gray Code Correction (Pin KORR)

This function blocksynchronizes the switchingpoints for the 11 bit gray codeof the digital signals D1 to D11with D0 and D09 (digitizedsignal of A0 and A09).

This Gray code correction onlyworks for the 12 bit MSB(4096steps per revolution).

It does not work for the 4excess interpolated bits of the16 bit Gray code.

When some special applicationsrequire code patterns otherthan Gray code, the Gray codecorrection can be disabled byputting pin KORR = 0. Whenthat happens just the 11 databits (D1…D11) will be sent 1:1to the DOUT serial output.

Gray code correction can beswitched on or off by puttingthe pin KORR =1 (on) or =0(off).

MSBINV and DOUT Pins

The serial interface consists ofa shift register. The mostsignificant bit, MSB (D11) willalways be sent first to DOUT.The MSB can be inverted(change code direction) byusing pin MSBINV.

DIN and NSL Pins

The Serial input DIN allowsthe configuration as ringregister for multipletransmissions or for cascading2 or more encoders. DIN isthe input of the shift registerthat shifts the data to DOUT.

The NSL pin controls the shiftregister, to switch it betweenload (1) or shift (0) mode.Under load mode, DOUT willgive the logic of the MSB, i.e.,D11.

Under shift mode (0), coupledwith the SCL, the register willbe clocked, and gives out theserial word output bit by bit.As the clock frequency can beup to 16 MHz, thetransmission of the full 16 bitword can be done within 1µs.

Valid data of DOUT should beread when the SCL clock islow. Please refer to timingdiagram (Figure 2).

3

Pinout Description

No. Pin Name Description Function Notes[1]

1 NC Internally connected to cathode of LED Do not use

2 KORR Digital-input 1 = Gray Code Correction Active CMOS, internal pu

3 PROBE_ON Digital-Input Do not use CMOS, internal pd

4 PCL Digital Input Do not use CMOS, internal puPositive Edge

5 STCAL Digital Input To be ground CMOS, internal pdPositive edgeNegative edge

6 MSBINV Digital-Input 1 = MSB inverted CMOS, internal pd

7 DIN Digital Input Shift Register input. Used for cascading only CMOS, internal pd

8 NSL Digital-Input Shift-register Shift (=0) / Load (=1) Control CMOS, internal pu

9 SCL Digital-Input Shift-register Shift Clock CMOS, internal puPositive Edge

10 DOUT Digital Output Shift-Register Data Out (MSB first) CMOS, 2 mA

11 DO Digital Output DO signal CMOS, 2 mA

12 DPROBE Digital Output DO9 signal CMOS, 2 mA

13 VDD Supply Voltage +5 V Supply Digital

14 GND Gnd for supply voltage GND for 5 V supply analog/digital

15 A09P Analog output A09 positive (+True diff.) CMOS, analog out

16 GND Gnd for supply voltage GND for 5 V supply analog/digital

17 A0P Analog Output A0 positive (+True diff.) CMOS, analog out

18 A09N Analog output A09 negative (–True diff.) CMOS, analog out

19 VDDA Supply Voltage +5 V Supply Analog

20 A0N Analog Output A0 negative (–True diff.) CMOS, analog out

21 LERR Digital Output IR-LED Current Limit Signal CMOS, 2 mA

22 LEDR Analog Output Do not use CMOS, analog out

Note:1. Internal pu/pd = internal pull-up (typ. 50 µA)/ pull-down (typ. 10 µA) CMOS-transistor-Rs.

Pinout Configuration

ESD WARNING: HANDLING PRECAUTIONS SHOULD BE TAKEN TO AVOID STATIC DISCHARGE

4

Using the AEAS-7000

Figure 1. Schematic using AEAS-7000.

Note: The RC-filter combination,especially on VDDA, is used to filterspikes and transients and is stronglyrecommended. It is advised that thetantalum caps be put as close to theVDD and VDDA pins as possible.

It is recommended to groundthe PROBE_ON pin duringnormal operation.

Leave PCL unconnected.

A09N and A0N are the negativecosine and sine waves, thenegative versions of A09P andA0P.

D0 is used to check the D0signal. D0 is the digitized signalof A0. DPROBE is used to checkD09, the digitized signal of A09.Recommended to be used fortesting purpose only.

KORR is for Gray Codecorrection for 12 bits resolutiononly.

MSBINV is for user to changebetween counting up andcounting down for a givenrotating direction. MSB(D11)will always be sent out toDOUT first.

LEDR, do not connect to thispin.

LERR will be high when thelight output of the emitter islow. This is an indicator whenlight intensity is at a criticalstage affecting the performanceof the encoder. It is caused bycontamination of the codewheelor LED degradation.

Operation

1) After powering up the unitusing VCC =+5 V andconnecting GND to ground,trigger input pins NSL andSCL using the timingdiagram below (Figure 2).NSL is a control pin for theinternal shift register. Whentriggered to low andcombined with clock pulses,the serial Gray code will beshifted out to DOUT bit bybit per every clock pulse

2) The 16 bit serial gray codecan then be tapped out fromthe pin DOUT, mostsignificant bit (D11) first.

The rate of the 16 bit Graycode serial transfer rate isdependent on the SCL clockfrequency. The faster theclock, the faster the transferrate. The maximum clock ratethe AEAS-7000 can take is 16MHz, which means the entire16 bit Gray code can beserially transferred out in 1µs.

3)Whenever NSL is high, theDOUT will have the logic ofthe MSB D11. After NSL goeslow, the number of bits beingtrans-ferred out will dependon the number of clock pulsesgiven to SCL. The default is16 clock pulses for the 16 bitGray code. If for otherapplication where anothernumber other than 16 isneeded, just supply thecorresponding number of clockpulses to the SCL, e.g., 12 bit,13 bit, 14 bit or 15 bit, andyou will get the correspondinglength of Gray code wordswith the correspondingresolution.

Ana

logu

e - O

utpu

ts

MSBINV

PCL

PROBE_ONKORRLERR

10R min 100µTantal

0R to 2R

Tantalmin 2µ2

VDD

VDD

(C's optional)

DIN

NSL

SCL

DOUT

GND

VCC

GND

VCC (+5V)

App

licat

ion

- Log

ic

D0 D09

STCAL

LERR

D0

KORR

PROBE_ON

A09N_AREF

GND

VDDA

A0P_A0

A0N_MON

A09P_APR

LEDR

PCL

MSBINV

DOUT

SCL

DIN

NSL

DPROBE

STCAL

VDD

5

Figure 2. Timing diagram.

Absolute Limits

No. Parameters Symbol Min. Typ. Max. Units

1 Supply Voltage VD –0.3 6.0 V

2 Voltages at all Input and Output Pins Vin , Vout –0.3 VD + 0.3 V

3 Operating Temperature TA –25 +85 °C

4 Storage Temperature TS –40 +100 °C

Operating Conditions

No. Parameters Symbol Min. Typ. Max Units

1 Supply Voltage VD 4.5 5 5.5 V

2 Operating Temperature TA –25 25 +85 °C

3 Input-H-Level Vih 0.7*VD VD V

4 Input-L-Level Vil 0 0.3*VD V

NSL

SCL

1 2 14 15 16

LAPSE TIMEBETWEEN WORDS,

SET BY NSL

1 FRAME = 16 BITS

Note: VALID DATA IS WHEN NSL IS LOW

D11 D10 D-3 D-4 D11DOUT(SERIAL)

Electrical Characteristics (VD = 4.5 to 5 V, TA = –40 to +85 °C)

No. Parameters Symbol Conditions Min. Typ. Max. Units

Operating Currents

1 Total Current I total 25 mA

Digital Inputs

1 Pull Down Current Ipd –20 –5 µA

2 Pull Up Current Ipu 30 160 µA

Digital Outputs

1 Ouput-H-Level Voh Ioh = 2 mA VD - 0.5 V VD V

2 Output-L-Level Vol Iol = –2 mA 0 0.5 V

Serial Interface

1 SCL Clock Frequency fclock 16 MHz

2 Duty Cycle Fclock T clock,LH Fclock = 16 MHz 0.4 0.6 ns

3 Accuracy (1) Fclock = 5MHz, ±2bitsRPM = 80

Analog-Signal-Conditioning – Signaltracks A0P, A0N,A09P,A09N

1. Signal Frequency A0, A09 Fsine,cos 0 250 KHz

Note 1:

Accuracy would be influenced by installation control and the bearing and shaft type being used.

Test conditions to determine Accuracy

1) 80 RPM

2) 25 oC, room temperature

3) At nominal radial, tangential and gap position

4) On dual preloaded bearing with absolute assembly concentricity of not exceedding 10 microns

5) SCL frequency of 5MHz

6) Both VDD & VDDA filter capacitor placed not more than 20mm from header pins

7) Tested for one revolution

Note: Codewheel mounting tolerances for radial, tangential and Z gap are:

Radial: ±50 um

Tangential: ±40 um

Z Gap: ±50 um

UNLESS SPECIFIED OTHERWISE

DIMENSIONS ARE IN MILLIMETRES

THIRD ANGLE PROJECTION

STRIKE OUTOR FILL INAS NEEDED

XX.XX.XXX.XX

0.30.10.03

21.2

Ø56

24.1

24.0

Ø8.02 H6

Ø42.1

18.8

5±0.

2

22.6 1.

5

3.65

0.35

+0.

15-0

.10

(Z g

ap b

etw

een

code

dis

c an

d re

ticle

)

9.2

35.1

12.0 Ø3.2 (2x)

Readhead

Code Disc

2x11 -1.27mm pitch pin header

Mounting Consideration

www.agilent.com/semiconductorsFor product information and a complete list ofdistributors, please go to our web site.

For technical assistance call:

Americas/Canada: +1 (800) 235-0312 or(916) 788-6763

Europe: +49 (0) 6441 92460

China: 10800 650 0017

Hong Kong: (+65) 6756 2394

India, Australia, New Zealand: (+65) 6755 1939

Japan: (+81 3) 3335-8152 (Domestic/Interna-tional), or 0120-61-1280 (Domestic Only)

Korea: (+65) 6755 1989

Singapore, Malaysia, Vietnam, Thailand,Philippines, Indonesia: (+65) 6755 2044

Taiwan: (+65) 6755 1843

Data subject to change.Copyright © 2004 Agilent Technologies, Inc.February 23, 20045988-9627EN

Plug & Play Hub-Shaft design

The following details the design of thehub-shaft of which the dimensionsmust be strictly followed for the plug &play feature of the AEAS-7000 to work.In order to secure the code disk to thehub, an adhesive must be utilised.Agilent recommends using DELO-DUOPOX, 1895 from DELO. Stainlesssteel is recommended as the hub-shaftmaterial.

AEA

Legend

1 = 5V G = gray code S = serial output mode

- 7000 - 1 G S

S - Standard(-25°C to +85°C)

0

D - 13 bitsG - 16 bits

Ordering Information

A complete instruction for AEAS-7000Plug & Play installation considerationcan be found in AEAS-7000 applicationnote.

Ø12

0.8 depth as adhesive reservoir 58

Ø16

Ø15

Ø11

20

0.01 A

0.02

0.01 A0.02

Ø0.01

12

4.2

0.01

A

Ø18

Ø10

h6

1 Ø8.

02h6

2

+0.03 -0

+0

- 0.0

1

+0

- 0.0

1 (

)

(

)

Motor end is user specified

Straightness

Flatness

Perpendicularity

Total Run-out

AEAS-7000 Plug and PlayInstallation Considerations

Application Note 5048

IntroductionAEAS-7000 comes in the form ofan absolute encoder read-headand absolute code disk. TheAEAS-7000 plug and play con-cept basically eliminates theneed for tedious manual align-ment of photodiodes and codedisk. Design of the AEAS-7000gives the user the ease of useduring installation with mini-mum alignment required.

Mounting Considerations forAEAS-7000Figure 1 shows the packageoutline of the AEAS-7000. Thedevice comes with a standard1.27 mm pitch header pin.

Figures 2 and 3 are guidelines formounting the AEAS-7000 to amotor bearing stage.

Figure 1. Package outline of the AEAS-7000.

2x11-1.27 mm pitch pin header

1.5

22.6

18.85±0.2

21

20 18 16 14 12 10 8 6 4 2 0

19 17 15 13 11 9 7 5 3 1

MountingHoles

AlignmentHoles

2

Figure 3. Mounting of AEAS-7000 on a bearing stage as shown in Figure 2.

24.1

21.2

9.2

24.0

12.0∅56

∅3.2 (2x)

∅42.1

∅8.02 H6

24.0

21.2

Dimensions are in millimeters.

M3 tap 8dp (2x) for mountingAEAS-7000 module

Bearing stage

Figure 2. Mounting hole dimensions for AEAS-7000.

3

In Figure 4, an example is givenof an application whereby theAEAS-7000 is mounted onto abearing stage with the code diskattached to a hub-shaft. The codedisk hub-shaft is not provided byAgilent Technologies.

Figure 5 details the design of thehub-shaft of which the dimen-sions must be strictly followedfor the plug and play feature ofthe AEAS-7000 to work.

Figure 5. Illustration of the hub-shaft design.

Figure 4. Mounting of AEAS-7000 on a housed-encoder flange.

Height difference between bottom ofcodewheel to AEAS-7000 mountingplane “Critical for Gap Alignment”

12 0/+1 (Recommended protrusion length)

8.02 h63.65±0.02(Height difference between bottom of codewheel to AEAS-7000 mounting plane "Critical for Gap Alignment")

Reservoir for adhesiveoverflow

Flat surface to apply adhesive

Protrusion forinsertion of Plugand Play tool

Reservoir for adhesive overflow

Protusion for insertionof Plug and Play tool

4

The hub-shaft is not provided byAgilent Technologies, and must befabricated by the customer as perdesign details in Figure 6. Inorder to secure the code disk tothe hub, an adhesive must beutilised. Agilent recommendsusing DELO-DUOPOX, 1895 fromDELO. Stainless steel is recom-mended as the hub-shaft material.

0.8 depth as adhesive reservoir

1 20

+0.034.2-0

12

0.01

0.02

A

0.01

0.02

A

58

2

0.01

∅12

∅10

ns ∅

18

∅8.

02 n

s

A

∅0.01

∅10∅11

∅15

∅16

Motor end is user specified

+0

-0.0

1 +0

-0.0

1

Straightness

Flatness

Perpendicularity

Total Run-out

Figure 6. Design detail of hub-shaft for plug and play features.

5

Codewheel to Hub AssemblyStep 1The code disk is secured on thecode disk hub-shaft with adhe-sive. Adhesive must be appliedon the flat surface of the hub asdetailed in Figure 5.

Step 2Referring to Figure 7, ensure thecode disk orientation is correctlypositioned. The artwork of thecode disk needs to be facingdown toward the detector. Theartwork is the opposite to theprotrusion on the inner diameterof the code disk.

Step 3Pressing near the ID of thecodewheel is required to ensurethe codewheel sits flush to thehub.

Step 4Adhesive Curing

Figure 7. Attaching the codewheel to hub-shaft assembly using a pressing jig.

Figure 8. Shows a shafted code disk assembled onto a bearing stage.

Pressing Jig

1 Kg

"Artwork side face down"Jig not supplied

6

AEAS-7000 InstallationStep 1AEAS-7000 must be carefullypositioned on the bearing stage.Care must be taken to avoidknocking the code disk duringthis process, which has a risk ofdamaging the code disk. Check toensure that the code disk still canmake a smooth rotation.

Step 2The encoder is secured with25 mm length M3 size screws.The mounting holes are used forthis purpose. At this point thescrews are not tightened, as thealignment process is next.

Step 3Next is the alignment process.Locate the plug and play tooleagle claw in the readheadalignment holes and the hubprotrusion. In this position theAEAS-7000 is correctly aligned tothe code disk.

Step 4With the plug and play tool inplace, the AEAS-7000 is correctlyaligned to the code disk. Tightenthe mounting screws to fix thelocation of the AEAS-7000 unit inthe aligned position. Whiletightening the screws, lightlypress a finger at the center of theplug and play tool. This willensure the tool sits flush on thecodewheel. Recommended torqueforce to secure the screw is 7 lbin or 0.79 Nm, which will able theunit to withstand vibrations ofup to 5G.

1

3

Slide the Plug and P lay tool fromthe top by locating the readheadthrough the alignment holes andhub protrusion

Eagle Claw

Tighten the mounting screwsbefore taking out the PNP tool

4

Cap screws are used to hold theAE AS-7000 unit to the bearingstage via the mounting hole.

www.agilent.com/semiconductorsFor product information and a complete list ofdistributors, please go to our web site.

For technical assistance call:

Americas/Canada: +1 (800) 235-0312 or(916) 788-6763

Europe: +49 (0) 6441 92460

China: 10800 650 0017

Hong Kong: (65) 6756 2394

India, Australia, New Zealand: (65) 6755 1939

Japan: (+81 3) 3335-8152(Domestic/International), or0120-61-1280(Domestic Only)

Korea: (65) 6755 1989

Singapore, Malaysia, Vietnam, Thailand, Philippines,Indonesia: (65) 6755 2044

Taiwan: (65) 6755 1843

Data subject to change.Copyright © 2004 Agilent Technologies, Inc.February 20, 20045989-0731EN