HEDS-970x, HEDS-972x Series
Digital Output Small Optical Encoder Modules
Data Sheet
Description
Features
The HEDS-9700 series is a high performance, low cost,
optical incremental encoder module. When operated
in conjunction with either a codewheel or codestrip,
this module detects rotary or linear position. The
module consists of a lensed LED source and a detector
IC enclosed in a small C-shaped plastic package. Due
to a highly collimated light source and a unique photodetector array, the module is extremely tolerant to
mounting misalignment.
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The two channel digital outputs and 5V supply input are
accessed through four solder-plated leads located on
2.54 mm (0.1 inch) centers.
The standard HEDS-9700 is designed for use with an 11
mm optical radius codewheel, or linear codestrip. Other
options are available. Please contact factory for more information.
Small Size
Low Cost
Multiple Mounting Options
Wide Resolution Range
Linear and Rotary Options Available
No Signal Adjustment Required
Insensitive to Radial and Axial Play
-40°C to +85°C Operating Temperature
Two Channel Quadrature Output
TTL Compatible
Single 5V Supply
Wave Solderable
Package Dimensions
Mounting Option #50 - Standard (Baseplane Mounting)
Contact Factory for Detailed Package Dimensions
ESD WARNING; NORMAL HANDLING PRECAUTIONS SHOULD BE TAKEN TO AVOID STATIC DISCHARGE.
Applications
Theory of Operation
The HEDS-9700 provides sophisticated motion detection
at a low cost, making closed-loop control very cost-competitive! Typical applications include printers, plotters,
copiers, and office automation equipment.
The HEDS-9700 is a C-shaped emitter/detector module.
Coupled with a codewheel, it translates rotary motion
into a two-channel digital output. Coupled with a
codestrip, it translates linear motion into a digital
output.
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 equipment. Please contact
sales representative if more clarification is needed.
As seen in the block diagram, the module contains a
single Light Emitting Diode (LED) as its light source. The
light is collimated into a parallel beam by means of a
single 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
processing circuitry necessary to produce the digital
VCC waveforms.
Block Diagram
RESISTOR
3
LENS
PHOTODIODES
LED
COMPARATORS
A
+
A B
+
B SIGNAL
PROCESSING
CIRCUITRY
EMITTER SECTION
2
CODE
WHEEL
DETECTOR SECTION
The codewheel/codestrip moves between the emitter
and detector, causing the light beam to be interrupted
by the pattern of spaces and bars on the codewheel/
codestrip. The photodiodes which detect these interrupCHANNEL A
tions are arranged in a pattern that corresponds to the
2
radius and count density of the codewheel/codestrip.
These detectors are also spaced such that a light period
CHANNEL B on one pair of detectors corresponds to a dark period on
the adjacent pair of detectors. The photodiode outputs
4
are fed through the signal processing circuitry. Two
comparators receive these signals and produce the final
outputs for channels A and B. Due to this integrated
GND phasing technique, the digital output of channel A is in
quadrature with channel B (90 degrees out of phase).
1
Pulse Width (P): The number of electrical degrees that
an output is high during one cycle. This value is nominally 180°e or 1/2 cycle.
Output Waveforms
C
AMPLITUDE
P
Pulse Width Error ('P): The deviation, in electrical deCHANNEL A grees, of the pulse width from its ideal value of 180°e.
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 90°e.
ф
S1
S2
S3
S4
CHANNEL B
State Width Error ('S): The deviation, in electrical degrees, of each state width from its ideal value of 90°e.
ROTATION
Phase (I): The number of electrical degrees between the
center of the high state of channel A and the center of
the high state of channel B. This value is nominally 90°e
for quadrature output.
Definitions
Count (N) = The number of bar and window pairs or
counts per revolution (CPR) of the codewheel, or the
number of lines per inch of the codestrip (LPI).
Phase Error ('I): The deviation of the phase from its
ideal value of 90°e.
Direction of Rotation: When the codewheel rotates
counterclockwise, as viewed looking down on the module (so the marking is visible), channel A will lead channel B. If the codewheel rotates in the opposite direction,
channel B will lead channel A.
1 Shaft Rotation = 360
mechanical
degrees
= N cycles
1 cycle (c) = 360 electrical
degrees (°e)
= 1 bar and
window pair
Optical Radius (Rop): The distance from the codewheel’s
center of rotation to the optical center (O.C.) of the
encoder module.
Absolute Maximum Ratings
3
Parameter
Storage Temperature
Operating Temperature
Supply Voltage
Output Voltage
Symbol
TS
TA
VCC
VO
Output Current per
Channel
Soldering Temperature
IO
Min.
-40
-40
-0.5
Max.
85
85
7
Units
°C
°C
V
-0.5
-1.0
VCC
5
V
mA
260
°C
Notes
See Note
See Note
t ≤5 sec.
Recommended Operating Conditions
Parameter
Symbol
Min.
Max.
Units
7
°C
Supply Voltage
VCC
4.5
5.5
V
Ripple < 100 mVp-p
Load Capacitance
CL
100
pF
3.2 k: pull-up
20
kHz
(Velocity (rpm) x N)/60
Temperature
Count Frequency
Notes
Note: The module performance is guaranteed to 20 kHz but can operate at higher frequencies. For operation at 30KHz for resolution options E, F,
G and H, the maximum pulse width and logic state width errors are 40°e and phase error is 15°e.
Encoding Characteristics
Encoding Characteristics over Recommended Operating Range and Recommended Mounting Tolerances. These
characteristics do not include codewheel/codestrip contributions.
Case 1
Case 2
Parameter
Symbol
Typ.
Max.
Max.
Units
Notes
Pulse Width Error
'P
7
30
40
°e
Logic State Width Error
'S
5
30
40
°e
Phase Error
'I
2
10
15
°e
Case 1: Module mounted on tolerances of ±0.13 mm (0.005”). Case 2: Module mounted on tolerances of ±0.25 mm
(0.010”)
Note: See Figures in Mounting Considerations for details on Case 1 and Case 2 mounting tolerances.
Electrical Characteristics
Electrical Characteristics over Recommended Operating Range, Typical at 25°C.
Parameter
4
Symbol
Supply Current
ICC
High Level Output Voltage
VOH
Low Level Output Voltage
VOL
Min.
Typ.
Max.
Units
17
40
mA
2.4
0.4
Notes
V
IOH = -40 μA
V
IOL = 3.2 mA
Rise Time
tr
200
ns
CL = 25 pF, RL = 11 k:
Fall Time
tf
50
ns
CL = 25 pF, RL = 11 k:
Recommended Codewheel and Codestrip Characteristics
Parameter
Symbol
Min.
Max.
Ww/Wb
0.7
1.4
Window Length (Rotary)
Lw
1.80
(0.071)
2.30
(0.091)
mm
(inch)
Absolute Maximum Codewheel
Radius (Rotary)
Rc
Rop + 3.40
(Rop + 0.134)
mm
(inch)
Center of Post to Inside
Edge of Window
W1
1.04
(0.041)
mm
(inch)
Center of Post to Outside
Edge of Window
W2
0.76
(0.030)
mm
(inch)
Window/Bar Ratio
Center of Post to Inside Edge
of Codestrip
Optional Packages Available
Mounting Option #51 – Rounded Outline (Baseplane Mounting)
5
L
3.60
(0.142)
Units
mm
(inch)
Notes
Includes eccen–
tricity errors
Optional Packages Available (cont’d.)
Mounting Option #52 – Backplane (Backplane Mounting)
Mounting Option #53 – Standard with Posts (Baseplane Mounting)
6
Optional Packages Available (cont’d.)
Mounting Option #54 – Tabless (Baseplane Mounting)
Mounting Option #55 – Backplane with Posts (Backplane Mounting)
7
Bent Lead Option
Mounting Considerations
Note: These dimensions include shaft end play and codewheel warp.
All dimensions for mounting the module and codewheel/codestrip should be measured with respect to the two mounting posts, shown above.
Mounting Tolerances
Case 1 and Case 2 specify the mounting tolerances required on Rm in order to achieve the respective encoding
characteristics shown on page 4. The mounting tolerances are as follows:
Case 1: Rm ± 0.13 mm (.005 inches)
Case 2: Rm ± 0.25 mm (.010 inches)
Recommended Screw Size: M2.5 x 0.45 or 2-56
8
Recommended Wave Solder Conditions
Flux – RMA Water Soluble (per MIL-F-14256D)
Process Parameters
1. Flux
2. Pre-heat 60 seconds total
Nominal preheat temp: 90°C
Min: 85°C Max: 110°C
3. Solder Pot Zone
Nominal dip in time:
2.5 - 4.5 seconds
Min: 2.5 seconds
Max: 5 seconds
PCB top side: 140 -160°C
PCB bottom side: 240 - 260°C
4. Wave Solder 255°C,
1.2 meters/minute line speed
5. Hot Water Wash
1st: 30°C 45 seconds
2nd: 70°C 90 seconds
6. Rinse
1st: 23°C 45 seconds
2nd: 23°C 45 seconds
7. Dry
1st: 80°C 105 seconds
2nd: 95°C 105 seconds
Typical Interface
CH A
HEDS–9700
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CH B
AVAGO
HCTL-20xx
QUADRATURE
DECODER/
COUNTER
HOST PROCESSOR
Ordering Information
HEDS-97
0 – Rotary
2 – Linear
Option
Lead Bend
0 – Straight Leads
1 – Bent Leads
Resolution Options
(11 mm optical radius, Rop)
K – 96 CPR
C – 100 CPR
D – 192 CPR
E – 200 CPR
F – 256 CPR
G – 360 CPR
H – 400 CPR
(Linear)
L – 120 LPI
M – 127 LPI
P – 150 LPI
Mounting Options
50 – Standard
51 – Rounded Outline
52 – Backplane
53 – Standard w/Posts
54 – Tabless
55 – Backplane w/Posts
Contact Factory for Other
Resolution Options
Note: Please contact factory for codewheel and codestrip information.
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HEDS-9700
HEDS-9701
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HEDS-9720
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HEDS-9721
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For product information and a complete list of distributors, please go to our web site:
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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 © 2005-2010 Avago Technologies. All rights reserved. Obsoletes 5988-8045EN
AV02-0511EN - February 5, 2010
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