HEDL - 64XX Series
Optical Incremental Housed Encoders
Data Sheet
Description
The HEDL-64XX series are high performance, cost effec-
tive, two-channel optical incremental housed encoders
with optional index pulse. These encoders emphasize
high reliability, high resolution and easy assembly. The
HEDL-64XX housed encoders use transmissive technol-
ogy to sense rotary position. This sensor consists of an
LED light source, a photodetector IC and line driver. The
outputs of the HEDL-64XX encoders are 2 square waves
in quadrature and and an optional gated index pulse.
These encoders may be quickly and easily mounted to
a motor.
Features
•
Two channel quadrature output with optional index
pulse
•
Quick and easy assembly
•
Cost-effective
•
Small form factor
•
IP50
•
Resolutions up to 512 Counts Per Revolution
•
-25°C to 90° operating temperature
•
Built-in RS 422 differential line driver
•
Hub available in 2,3 and 4 mm shaft sizes.
•
Coupling plate or threaded mount mounting options
available
Available Styles
Threaded Hole Version
Coupling Plate Version
Theory of Operation
The HEDL-64XX translates rotary motion of a shaft into a
two or three channel digital output. The HEDL-64XX se-
ries has four key parts: a single light emitting diode (LED)
light source, a photodetector IC with a set of uniquely
configured photodiodes , a line drive IC and a pair of
lenses. The lens over the LED focuses light onto the code-
wheel. As the codewheel rotates, an alternating pattern
of light and dark corresponding to the pattern of the
codewheel falls upon the photodiodes.
This light is used to produce internal signals A and A’, and
B and B’.
As part of this “push-pull” detector system, these signals
are fed through comparators and line driver that are part
of the signal processing circuitry to produce the final
outputs for channels A and B and index.
Cycle error(∆C):: An indication of cycle uniformity. The
difference between an observed shaft angle which gives
rise to one electrical cycle and the nominal angular incre-
ment of 1/N of a revolution
Pulse Width (P): The number of the electrical degrees that
an output is high during one cycle, nominally 180°e or
1/2 a cycle.
Pulse Width Error(∆P): The deviation in electrical degrees
of the pulse width from its ideal value of 180°e.
State Width (S): The number of the electrical degrees be-
tween a transition in the output of the channel B. There
are 4 states per cycle, each nominally 90°e.
State Width Error (∆S): The deviation in electrical degrees
of each state width from its ideal value of 90°e.
Phase (f ): The number of electrical degrees between the
center of the high state on the channel A and the cen-
ter of the high state of channel B. This value is nominally
90°e.
Phase error (∆f ): The deviation in electrical degrees of the
phase from its ideal value of 90°e.
Position error (∆q):: The normalized angular difference
between the actual shaft position and the position indi-
cated by the encoder cycle count.
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 ¼ cycle.
Definitions
Count (N): For rotary motion, the number of bar and
window pairs or counts per revolution(CPR) of the code-
wheel. For linear motion, the number of bar and window
pairs per unit length (lines per inch[LPI] or lines per mm
[LPmm]).
One Cycle(C): 360 electrical degree(°e), 1 bar and win-
dow pair.
One Shaft Rotation: 360 mechanical degrees, N cycles
(rotary motion only).
Line Density: The number of reflective and non-reflec-
tive pairs per unit length, expressed as either lines per
inch(LPI) or lines per mm (LPmm).
RESISTO
R
PHOTODIODE
S
Vcc
Ch A
Ch A
LED
LENS
SIGNA
L ROCESSIN
P
GIRCUITR
C
Y
Ch B
Ch B
I
I
CODEWHEE
L
Gnd
Output Waveforms
C
P
Channel A
s1
Amplitude
t
1
t
2
P
0
Index
s2
s3
s4
o
Channel B
Codewheel
Direction of Motor Rotation
When the codewheel rotates in the clockwise direction
(top view), channel A will lead channel B. If the code-
wheel rotates in the counterclockwise direction, channel
B will lead channel A.
Pin Assignment Signal
PIN 1
PIN 2
PIN 3
PIN 4
PIN 5
PIN 6
PIN 7
PIN 8
Ch A
Ch A’
Ground
Ch B
Ch B’
Vcc
Index
Index’
Description
Digital output
Digital output
Ground
Digital output
Digital output
Input voltage
Digital output
Digital output
Rotation
Absolute Maximum Ratings
Storage Temperature
Operating Temperature
Supply Voltage
Output Voltage
Output Current per Channel
Frequency
Notes:
rpm = frequency * 60 / cpr
Absolute Maximum Rating are those values beyond which the safety
of the device cannot be guaranteed. They are not meant to imply that
the device should be operated at these limits. The table “Recommend-
ed Operating Conditions and Characteristics” provides conditions for
actual device operation.
-40°C to 100°C
-25°C to 90°C
4.5 V to 5.5 V
-0.5 V to 5.5V
-2.0 mA to 25 mA
100 kHz
Recommended Operating Conditions
Parameter
Temperature
Supply Voltage
Symbol
T
A
V
CC
Min.
0
4.5
Typical
25
5.0
Max.
90
5.5
Units
°C
Volts
Notes
Electrical Characteristics (over recommended operating conditions Typically at 25°C)
Parameter
Supply Current
High level Output Voltage
Low level Output Voltage
Symbol
I
CC
V
OH
V
OL
2.4
0.2
Min.
Typical
40
Max.
65
Units
mA
V
V
I
OH
= -2 mA min.
I
OL
= 25 mA max
Notes
Notes
This device meets the ESD ratings below:
Class C per EIA/JESD22-A115-A (MM)
Class 1C per JESD22-A114-B (HBM)
Encoding Characteristics
Parameter
Pulse Width Error
State Width Error
Phase Error
Position Error
Cycle Error
Index Pulse Width
Index rise time after Ch B fall
Index fall time after Ch A rise
Symbol
∆P
∆S
∆f
∆Q
∆C
P
o
t
1
t
2
Typical
7
15
15
40
10
90
500
150
Max.
70
60
60
120
45
120
800
500
Units
°e
°e
°e
arcmin
°e
°e
ns
ns
Mechanical Characteristics (refer to page 2 and 3 for details)
Parameter
Recommended Motor Shaft Diameters
Adhesive Mount
(recommended mounting glue type is Hernon 823 anaerobic
glue or equivalent)
Allowable Motor Shaft Length:
Coupling plate
Threaded mount
Bolt Circle Diameter :
Coupling plate
Threaded mount
Mounting Screw Size:
Coupling plate
Threaded mount
Max axial load
Max radial load
Bearing life (based on the above loading)
Unit weight
Sealing (per IEC 529)
Humidity
Vibration (per IEC 68-2-27)
Shock (per IEC 68-2-27)
Dimension/Details
2, 3, 4
Tolerance
+/-.01
(+/-.0004)
Units
mm
(in)
11.6 max
11.0 max
28.6
15.90
M2
M2x 3.5
0.3
0.3
2 x 10
10
22
IP50
98% RH max
Non condensing
20g @ 10 Hz ~ 500 Hz
30 g @ 11ms
+/-0.1
+/-0.05
mm
mm
mm
kgf
kgf
rev
gm
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