Agilent AEDR-8300 Series Encoders
Reflective Surface Mount Optical Encoder
Data Sheet
Description
The AEDR-8300 series is the
smallest optical encoder employ-
ing reflective technology for
motion control purposes. The
encoder houses an LED light
source and a photo-detecting
circuitry in a single package.
The AEDS-8300 series offers
options of either single channel
or two-channel quadrature digital
outputs. Being TTL compatible,
the outputs of the AEDR-8300
series can be interfaced directly
with most of the signal process-
ing circuitries. Hence the encoder
provides great design-in flexibil-
ity and easy integration into
existing systems. The AEDR-8300
series is available in four resolu-
Features
Reflective technology
Surface mount small outline
leadless package
Single channel incremental output
Two channel quadrature outputs for
direction sensing
TTL compatible output
Single 5V supply
-20
o
C to 85
o
C absolute operating
temperature
Encoding resolution options:
36, 75, 150, 180 (lines/inch) or
1.42, 2.95, 5.91, 7.09 (lines/mm)
tions, namely 36, 75, 150 and 180
lines per inch (LPI) (1.42, 2.95, 5.91
and 7.09 lines per mm respec-
tively). This range of resolutions
caters for different design and
application needs.
Applications
The AEDR-8300 series provides
motion sensing at a competitive
cost, making it ideal for high
volume applications. Its small
size and surface mount package
make it ideal for printers, copi-
ers, card readers and many
consumer products, particularly
where space and weigh are
design constraint.
Note: All specifications are subject to change without prior notification.
2
Theory of Operation
The AEDR-8300 series 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 digital outputs.
As seen in the block diagram, the
AEDR-8300 consists of three
major components: a light emit-
ting diode (LED) light source, a
detector IC consisting photo-
diodes and lens to focus light
beam from the emitter as well as
light falling on the detector.
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 digital
outputs representing the rotation
of the codewheel. When the
codewheel is coupled to a motor,
the encoder outputs is then a
direct representation of the
motor rotation. The same con-
cept applies to the use of a
codestrip to detect linear motion.
Definitions
State Width (S)
: The number of
electrical degrees between a
transition in Channel A and the
neighboring transition in Chan-
nel B. There are 4 states per
cycle, each nominally 90
o
e.
State Width Error (
S): The
deviation of state width, in
electrical degree, from its ideal
value of 90
o
e.
Phase (
): The number of electri-
cal degrees between the center of
high state of Channel A and the
center of high state of Channel B.
Nominally 90
o
e.
Phase Error (
): The deviation
of phase, in electrical degree,
from its ideal value of 90
o
e.
Pulse Width (P)
: The duration of
high state of the output, in
electrical degree, within one
cycle. Nominally 180
o
e or half a
cycle.
Pulse Width Error (
P): The
deviation of pulse width, in
electrical degree, from its ideal
value of 180
o
e.
Count (N)
: The number of
window and bar pair per revolu-
tion (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 (
o
e). Equivalent to one
window and bar pair.
One Shaft Rotation
: 360 me-
chanical degrees. Also equivalent
to N counts (codewheel only).
Line Density
: The number of
window and bar pair per unit
length, expressed in either lines
per inch (LPI) or lines per mm
(LPmm).
Optical radius (Rop)
: The
distance between the codewheel
center and the centerline be-
tween the two domes of the
encoder.
Figure 1. Block Diagram of AEDR-8300.
V
LED
GND
V
CC
CH A
CH B
GND
SIGNAL
PROCESSING
CIRCUITRY
R
CODEWHEEL
OR
CODESTRIP
3
Gap (G)
: The distance from
surface of the encoder to the
surface of codewheel or
codestrip.
Specular Reflectance (R
f
)
: 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).
AEDR-8300
SHAFT
CODEWHEEL
RADIAL (E
R
)
TANGENTIAL (E
T
)
AEDR-8300
SHAFT
CODEWHEEL
ANGULAR (E
A
)
S1
S2
S3
S4
P
C
CH. B
CH. A
ALL FOUR STATES (S1 TO S4)
ARE MAINTAINED.
CODEWHEEL ROTATION OR LINEAR MOVEMENT
AMPLITUDE
Radial and Tangential Mis-
alignment Error (E
R
, E
T
)
: For
rotary motion, mechanical dis-
placement in the radial and
tangential directions relative to
the nominal alignment.
Angular Misalignment Error
(E
A
)
: Angular displacement of
the encoder relative to the
tangential line.
4
AEDR-8300 Absolute Maximum Ratings
Storage Temperature, T
S
-40
C to 85C
Operating Temperature, T
A
-20
C to 85C
Supply Voltage, V
CC
-0.5 V to 7 V
Output Voltage, V
O
-0.5 V to V
CC
Output Current per Channel, I
OUT
-1.0 mA to 8 mA
ESD
Human Body Model JESD22-A114-A Class 2
Machine Model JESD22-A115-A Class B
Notes:
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.
AEDR-8300 Recommended Operating Conditions
Parameter
Sym.
Min.
Typ.
Max.
Units
Notes
Temperature
T
A
0
25
85
C
Supply Voltage
V
CC
4.5
5
5.5
V
Ripple< 100mVp-p
LED Current
I
LED
13
15
18
mA
See note 1
Load Capacitance
C
L
100
pF
2.7 k
Pull-Up
Count Frequency
f
30
kHz
AEDR-83X0-K/P/Q
See Note 2
Count Frequency
f
15
kHz
AEDR-8310-V
Radial Misalignment
E
R
0.38 (0.015)
mm (in.)
Tangential Misalignment
E
T
0.38 (0.015)
mm (in.)
Angular Misalignment
E
A
0
1.5
deg.
Codewheel/strip tilt
C
T
0
1
deg.
Codewheel/strip Gap
G
1.0 (0.04)
2.0 (0.08)
2.5 (0.10)
mm (in.)
Note:
1. Refer to "LED Current Limiting Resistor" in Page 6.
2. Count frequency = velocity(rpm)xN/60.
5
AEDR-8300 Encoding Characteristics
Encoding characteristics over the recommended operating condition and mounting conditions.
Parameter
Symbol
Typical
Maximum
Units
Notes
Pulse Width Error
P
15
55
e
AEDR-8310-K
16
75
e
AEDR-8310-V
Pulse Width Error (Ch.A, Ch. B)
P
15, 25
55, 75
e
AEDR-8300-K
P
16
75
e
AEDR-8300-P
P
16
75
e
AEDR-8300-Q
Phase Error
12
60
e
AEDR-8300-K
10
60
e
AEDR-8300-P
10
60
e
AEDR-8300-Q
Note:
1.
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.
AEDR-8300 Electrical Characteristics
Characteristics over recommended operating conditions at 25
C.
Parameter
Sym.
Min.
Typ.
Max.
Units
Notes
Detector Supply Current
I
CC
2.2
5.0
mA
High Level Output Voltage
V
OH
2.4
V
I
OH
= 0.2 mA
Low Level Output Voltage
V
OL
0.4
V
I
OL
= 8.0 mA
Rise Time
t
r
500
ns
C
L
= 25 pF, R
L
= 2.7 k
Fall Time
t
f
100
ns
C
L
= 25 pF, R
L
= 2.7 k
AEDR-8300 Encoder Pin Configuration
Encoder option
Pin 1
Pin 2
Pin 3
Pin 4
Pin 5
Pin 6
AEDR-8310-K/V
NC
Gnd
V
LED
Gnd
Ch A
V
cc
AEDR-8300-K/P/Q
Ch B
Gnd
V
LED
Gnd
Ch A
V
cc
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