HEDT-9141#I00 Avago Technologies US Inc., HEDT-9141#I00 Datasheet - Page 3

• Manufacturer Part Number: HEDT-9141#I00
• Description: Encoders 3 Channel 512CPR
• Manufacturer: Avago Technologies US Inc.
• Type: Optical Encoderr

Specifications of HEDT-9141#I00

• Pulses Per Revolution: 2048
• Detents: No
• Motion: Rotary
• Number Of Channels: 3
• Mounting Style: Through Hole
• Index Output: Indexed
• Encoder Signal: Digital
• Built In Switch: No
• Operating Supply Voltage (typ): 5VDC
• Operating Temperature Min Deg. C: -40C
• Terminal Type: PC Pins
• Termination Style: Solder Pin
• Supply Voltage: 5 V
• Product: Optical
• Technology: Rotary
• Lead Free Status / RoHS Status: Compliant

Theory of Operation
The HEDT-9040 and 9104 are emitter/detector modules.
Coupled with a codewheel, these modules translate the
rotary motion of a shaft into a threechannel digital output.
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 waveforms.
The codewheel rotates between the emitter and detector,
causing the light beam to be interrupted by the pattern
of spaces and bars on the codewheel. The photodiodes
which detect these interruptions are arranged in a
pattern that corresponds to the radius and design of the
Block Diagram
3
LED
EMITTER
SECTION
RESISTOR
LENS
WHEEL
CODE
DIODES
PHOTO
SIGNAL PROCESSING
CIRCUITRY
DETECTOR SECTION
COMPARATORS
A
A
B
B
I
I
codewheel. These detectors are also spaced such that a
light period on one pair of detectors corresponds to a
dark period on the adjacent pair of detectors. The photo-
diode outputs are then fed through the signal processing
circuitry resulting in A, A, B, B, I and I. Comparators receive
these signals and produce the fi nal outputs for channels
A and B. Due to this integrated phasing technique, the
digital output of channel A is in quadrature with that of
channel B (90 degrees out of phase).
The output of the comparator for I and I is sent to the
index processing circuitry along with the outputs of
channels A and B. The fi nal output of channel I is an index
pulse Po which is a one state width (nominally 90 electri-
cal degrees), high true index pulse. This pulse is coincident
with the low states of channels A and B.
+
+
+
−
−
−
PROCESSING
CIRCUITRY
INDEX-
4
3
5
2
1
V
CH. A
CH. B
CH. I
GND
CC