AEAS - 7500
Ultra-Precision 16 bit Gray Code Absolute
Encoder Module
Data Sheet
Description
The encoder IC consists of 13 signal photo diode channels
and 1 monitor photo diode channel and is used for the
optical reading of rotary or linear code carriers (i.e. discs or
scales). The photodiodes are accompanied with precision
amplifiers plus additional circuitry.
The monitor channel is used to drive a constant current
source for the highly collimated IR illumination system.
Functional Description
Background
The 13 signal channels are set up as:
1. Two precision defining signals (A0, A09), which are two
90° electrical shifted sine, cosine signals. These signals
are conditioned to be compensated for offset and gain
errors. After conditioning they are on-chip interpolated
and computed to a combined absolute 16 bit Gray code,
together with signal channels A1-A11.
2. 11 analog (A1-A11) channels, which are directly digitized
by precision comparators with hysteresis tracking. The
digitized signals are called D1-D11.
3. An internal correction and synchronization module
allows the composition of a true 16 bit gray code by
merging the data bits of (1) and (2) by still keeping the
code monotonic.
4. There is a Gray code correction feature for this encoder.
This Gray code correction can be disabled/enabled by
the pin KORR.
5. The gain and offset conditioning value of the sine and
cosine signals are preloaded on-chip by factory. This
will minimize mechanical sensor misalignment error.
Features
• Two Sine/Cosine true differential outputs with 1024
periods for unit alignment
• Integrated highly collimated illumination system
• 11 digital tracks plus 2 sin/cos tracks generate precise
16 bit Gray code
• Ultra fast, 1µs cycle for serial data output word equals
16MHz
• The 12 bits MSB is functionable up to 12000 RPM, 16
bit up to 1000RPM
• MSB can be inverted for changing the counting direc-
tion
• Monitor track for tracking the light level of the LED
• Watch dog with alarm output pin LERR
• -25 °C to + 85 °C operating temperature
Benefits
• No battery or capacitor required for position detection
during power failure
• Immediate position detection on power up
Applications
• Rotary application up to 16 bits / 360° absolute
position
• Cost effective solution for direct integration into OEM
systems
• Linear positioning system
AVAGO [ AVAGO TECHNOLOGIES LIMITED ]
