AVAGO AEDR-83200Q1 Reflective surface mount optical encoder Datasheet

AEDR-8320 Encoder
Reflective Surface Mount Optical Encoder
Data Sheet
Description
Features
The AEDR-8320 encoder is an analog output encoder
that employs optical reflective technology for rotary and
linear movement control.
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With the introduction of reflective technology, encoder
packages can now be made smaller and weigh significantly lighter. This statement is better reflected in the
ability of the AEDR-8320 encoder which can easily fit into
many space and weight constraint applications, e.g., CD
or DVD writer laser head’s linear movement.
The AEDR-8320 comes in a 180 LPI (Lines Per Inch) or
7.09 mm lines per mm. In addition its 2-channel analog
outputs can obtain higher resolution through interpolation of 2x, 4x, 8x or more. For example, with 8x interpolation, the final resolution of the encoder will yield 1,440
lines per inch, which is approximately 20 µm accuracy.
AEDR-8320 encoder enhances design flexibility and provides an easy-to-assemble solution to a wide variety of
applications, while continuously ensuring reliability in
performance.
Reflective technology
Surface mount leadless package
Two-channel analog voltage output
Lead free package
-10°C to 70°C operating temperature
Encoding resolution:
180 (lines/inch) or 7.09 (lines/mm)
Applications
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Printers
Copiers
CD/DVD writer
Card readers
Theory of Operation
Definitions
The AEDR-8320 encoder combines an emitter and a detector in a single surface mount, leadless package. When
used with a codewheel or linear codestrip, the encoder
translates rotary or linear motion into analog outputs. As
shown in the block diagram below, the AEDR-8320 encoder consists of three major components: a light emitting diode (LED) light source, a detector IC consisting
photodiodes and lens to focus light beam from the emitter as well as light falling on the detector.
State Width (S): The number of electrical degrees between a transition in Channel A and the neighboring
transition in Channel B. There are 4 states per cycle, each
nominally 90°e.
The operation of the encoder is based on the principle
of optics where the detector photodiodes sense the
absence and presence of light. In this case, the rotary/
linear motion of an object being monitored is converted
to equivalent light pattern via the use of codewheel/
codestrip. As shown in the above diagram, the reflective
area (window) of the codewheel (or codestrip) reflects
light back to the photodetector IC, whereas no light is
reflected by the non-reflective area (bar). An alternating light and dark patterns corresponding to the window and bar fall on the photodiodes as the codewheel
rotates. The moving light pattern is exploited by the detector circuitry to produce analog outputs representing
the rotation of the codewheel. When the codewheel is
coupled to a motor the encoder outputs are then a direct
representation of the motor rotation. The same concept
applies to the use of a codestrip to detect linear motion.
Block Diagram of AEDR-8320
VLED
R
CODEWHEEL
or
CODESTRIP
VCC
Phase Error (Df): The deviation of phase, in electrical degree, from its ideal value of 90°e.
Pulse Width (P): The duration of high state of the output,
in electrical degree, within one cycle. Nominally 180°e or
half a cycle.
Pulse Width Error (DP): The deviation of pulse width, in
electrical degree, from its ideal value of 180°e.
Count (N): The number of window and bar pair per revolution (CPR) of codewheel. For linear codestrip, defined
as the number of window and bar pair per unit length
(lines per inch [LPI] or lines per mm [LPmm]).
One Cycle (C): 360 electrical degrees (°e). Equivalent to
one window and bar pair.
One Shaft Rotation: 360 mechanical degrees. Also
equivalent to N counts (codewheel only).
Optical radius (Rop): The distance between the codewheel center and the centerline between the two domes
of the encoder.
Gap (G): The distance from surface of the encoder to the
surface of codewheel or codestrip.
CH A
SIGNAL
PROCESSING
CIRCUITRY
Radial and Tangential Misalignment Error (ER, ET): For
rotary motion, mechanical displacement in the radial and
tangential directions relative to the nominal alignment.
GND
Angular Misalignment Error (EA): Angular displacement of the encoder relative to the tangential line.
RADIAL (ER)
ANGULAR (EA)
TANGENTIAL (ET)
AEDR-8320
AEDR-8320
SHAFT
SHAFT
CODEWHEEL
CODEWHEEL
NOTE: DRAWING
NOT TO SCALE
Phase (f): The number of electrical degrees between the
center of high state of Channel A and the center of high
state of Channel B. Nominally 90°e.
Line Density: The number of window and bar pair per
unit length, expressed in either lines per inch (LPI) or
lines per mm (LPmm).
GND
CH B
State Width Error (DS): The deviation of state width, in
electrical degree, from its ideal value of 90°e.
Specular Reflectance (Rf ): The amount of incident light
reflected by a surface. Quantified in terms of the percentage of incident light. A spectrometer can be used to measure specular reflectance of a surface (contact factory for
more information).
Output Waveform
PXA
PXB
SX1
SX2
SX3
SX4
CH B
VX12
VX34
CH A
2.5 V
VPP
VX56
CH B
VX78
PA
PB
S1
S2
S3
S4
VOFFSET
2.5 V
0V
VP
VPP
VM
Test Parameter Definitions
Name
Symbol
Definition
State Width
S1, S2, S3, S4 The number of electrical degrees between a transition in channel A and
the neighboring transition in channel B. There are 4 states per cycle, each
nominally 90°e.
The transitions are determined by where the analog signal crosses the 2.5 V
voltage level.
State Width Error
DS1, DS2,
DS3, DS4
The deviation, in electrical degrees, of each state width from its ideal value
of 90°e.
Pulse Width
PA, PB
The number of electrical degrees that an analog output is greater than 2.5 V
during one cycle. This value is nominally 180°e or 1/2 cycle.
Pulse Width Error
DPA, DPB
The deviation, in electrical degrees, of each pulse width from its ideal value
of 180°e.
State X Width
SX1, SX2,
SX3, SX4
The number of electrical degrees between a transition in channel A and
neighboring transition in channel B. There are 4 states per cycle, each
nominally 90°e.
The transitions are determined by where the channel A analog signal crosses
with channel B (or its complimentary) signal.
State X Width Error
DSX1, DSX2,
DSX3, DSX4
The deviation, in electrical degrees of each state X width from its ideal value
of 90°e.
Pulse X Width
PXA, PXB
Pulse X width A is the number of electrical degrees that analog A output is
greater than analog B output during one cycle.
Pulse X width B is the number of electrical degrees that analog B output is
greater than analog A during one cycle.
These value are nominally 180°e or 1/2 cycle.
Pulse X Width Error
DPXA, DPXB
The deviation, in electrical degrees of each pulse X width from its ideal value
of 180°e.
Analog Peak-toPeak
VPP
The peak-to-peak signal magnitude in V of the analog signal.
Analog Offset
VOFFSET
The offset in mV from the mid-point of the analog peak-to-peak signal to the
zero voltage point.
Analog Peak
Voltage
VPA, VPB
VMA, VMB
The value in V of the peak and valley of the analog signal (i.e., one-sided
reading).
Analog Peak to Peak VPPA, VPPB
Voltage
The absolute difference between VP and VM of channel A or B.
Analog Crosspoint
Voltage
Vx12, Vx34
Vx56, Vx78
The intersections in V of channel A analog waveform with that of either
channel B or its component.
Analog Offset
Voltage
VOFFSETA,
VOFFSETB
The offset in mV from the mid-point of the analog peak to peak signal to
2.5 V.
Linearity Error
DLinearity
Ration (in percentage) of maximum voltage deviation from a straight line
connecting adjacent upper and lower crosspoint voltages to the difference
between crosspoint voltages.
Absolute Maximum Ratings
Parameter
Symbol
Min.
Max.
Units
Notes
Storage Temperature
TS
-40
85
°C
Operating Temperature
TA
-10
70
°C
Supply Voltage (Detector)
VCC
-0.5
7
V
Output Voltage
Va , Vb
-0.5
Vcc + 0.4
V
DC Forward Current (LED)
ILED
40
mA
VF < 3 V
Reverse Voltage
VR
5
V
IR = 100 µA
Note:
1. Exposure to extreme light intensity (such as from flashbulbs or spotlights) may cause permanent damage to the device.
2. CAUTION: It is advised that normal static precautions should be taken when handling the encoder in order to avoid damage and/or degradation
induced by ESD.
3. Proper operation of the encoder cannot be guaranteed if the maximum ratings are exceeded.
Recommended Operating Conditions
Parameter
Symbol
Min.
Typ.
Max.
Units
Notes
Operating Temperature
T
-10
25
70
°C
Supply Voltage (Detector)
VCC
4.75
5.0
5.25
V
Ripple < 100 mV Vpp
Output Frequency
F
NA
5
20
kHz
(Velocity (rpm) x N)/60
DC Forward Current (LED)
ILED
16
20
30
mA
See note 1
Note:
1. LED Current Limiting Resistor
A resistor to limit current to the LED is required.
For 3.3 V LED Supply Voltage: The recommended value series resistor is 47 Ω (±10%).
For 5.0 V LED Supply Voltage: The recommended resistor value will be 110 Ω (±10%).
This will result in an LED current of approximately 20 mA.
Electrical Characteristics
Characteristics over recommended operating conditions at 25°C.
Parameter
Symbol
Min.
Typical
Max.
Units
Supply Current (Detector)
ICC
NA
5
8
mA
LED Forward Voltage
VF
NA
2.6
3.0
V
Notes
IF = 20 mA typical
Encoding Characteristics
Encoding characteristics over the recommended operating condition and mounting conditions.
Parameter
Symbol
Max.
Unit
State Width Error
DS
±40
°e
Pulse Width Error
DP
±40
°e
State X Width Error
DSX
±40
°e
Pulse X Width Error
DPX
±40
°e
Parameter
Symbol
Min.
Typ.
Max.
Unit
Peak to Peak Voltage (Average)
VPPA, VPPB
0.8
1.5
3.0
V
Analog Offset Voltage
VOFFSETA, VOFFSETB
-350
NA
350
mV
Linearity Error
∆Linearity
NA
5.0
12.5
%
Note: Typical values represent the encoder performance at typical mounting alignment, whereas the maximum values represent the encoder
performance across the range of recommended mounting tolerance.
Part Mounting Tolerances
Min.
Typ.
Max.
Units
Radial Misalignment from Nominal
-0.2
0
0.2
mm
Tangential Misalignment from Nominal
-0.2
0
0.2
mm
Gap Distances Between Codewheel and Detector IC
0.8
1.5
2.0
mm
Angular Misalignment
-1
0
1
deg
Recommended Codewheel and Codestrip Characteristics
CODEWHEEL
Ww = Wb = 70.5 µm (180 LPI)
CODESTRIP
Wb
Ww
Lw
Lw
Rop
Wb, NON-REFLECTIVE AREA
Ww, REFLECTIVE AREA
Parameter
Symbol
Min.
Max.
Window/Bar Ratio
Ww/Wb
0.9
1.1
Window/Bar Length
LW
1.80
(0.071)
2.31
(0.091)
Specular Reflectance
Rf
60
85
Reflective area. See note 1.
–
10
Non reflective area
Line Density
LPmm
(LPI)
Optical Radius
Rop
7.09
(180)
11
Notes:
1. Measurements from TMA µScan meter. Contact factory for more information.
2. Contact factory for more information on compatibility of codewheel/strip.
Moisture Sensitive Level
The AEDR-8320 is specified to moisture sensitive level (MSL) 3.
Unit
Notes
mm
(inches)
lines/mm
(lines/inch)
mm
Recommended value
Outline Drawing
0.75
2.70
4.20
CHAMFER
B
0.65
VCC
GND
A
GND
A
VLED
GND
6.50
1.58
BOTTOM VIEW
TOP VIEW
1.69
DETECTOR
EMITTER
SIDE VIEW
NOTES:
1. ALL DIMENSIONS IN MILLIMETERS.
2. TOLERANCE X.XX ± 0.15 mm.
Encoder Orientation
The AEDR-8320 is designed such that both the LED and
detector IC should be placed parallel to the window/bar
orientation, as shown. As such, the encoder is tolerant
against radial play of ± 0.20 mm. The emitter side should
be placed closer to the rotating shaft.
CODEWHEEL
CODESTRIP
DIRECTION OF
RADIAL PLAY
DIRECTION OF
RADIAL PLAY
NOTE: DRAWING NOT TO SCALE
Mounting Consideration
CODEWHEEL/CODESTRIP
GAP
ROP
11.00 mm (0.433 IN) < ROP < ∞
NOTE: DRAWING NOT TO SCALE
Direction of Codewheel Rotation
With the emitter side of the encoder placed closer to the
codewheel centre, Channel A leads Channel B when the
codewheel rotates anti-clockwise and vice versa.
ANTI-CLOCKWISE
CLOCKWISE
EMITTER
EMITTER
CH. A LEADS
CH. B LEADS
CH. B
CH. A
VIEWED FROM TOP
NOTE: DRAWING NOT TO SCALE
Recommended Land Pattern for AEDR-8320
0.7 mm
1.6 mm
3.3 mm
0.9 mm
10
NOTE: THE SHADED AREAS
ARE THE LEADS FOR SOLDERING
Recommended Lead-Free Reflow Soldering Temperature Profile
10 - 20 SEC.
300
255°C
250°C
TEMPERATURE (°C)
250
217°C
200
120 SEC. MAX.
60 - 150 SEC.
150
125°C
100
50
0
40°C
1
22
45
66
87
108
129
150
171
192
213
235
256
278
299
320
341
363
384
TIME (SEC.)
HEAT UP
SOLDER PASTE DRY
PREHEAT TEMPERATURE 40°C to 125°C
TEMPERATURE MAINTAIN ABOVE 217°C
PEAK TEMPERATURE
TIME ABOVE 250°C
=
=
=
=
SOLDER REFLOW
COOL DOWN
120 SEC. MAX.
60 – 150 SEC.
250 ± 5°C
10 – 20 SEC.
Note: Due to treatment of high temperature, AEDR-8320 compound
may turn yellow after IR reflow.
Ordering Information
Revision History
AEDR-8320 Option ___ ___ ___
Rev.
Date
Note
0
August 2006
Preliminary datasheet creation
1
February 2007
Release data sheet
Shipping Units
0 – 1000 pcs
2 – 100 pcs
Resolution
Q – 180 LPI
Packaging
1 – Tape and Reel
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 © 2007 Avago Technologies Limited. All rights reserved.
AV02-0233EN - August 10, 2007
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