iC-TW8 16-BIT SIN/COS INTERPOLATOR
Pin Configuration Mode
Jan 9, 2013 Page PC2/15
About This Document
This document describes the pin configuration mode
of the iC-TW8 Interpolator. Pin-configuration mode
provides simple, static configuration of the device
without any programming or complicated calibra-
tion.
Design tools for both rotary and linear encoders us-
ing the iC-TW8 are available. These tools are in the
form of Excel spreadsheets that allow entering ap-
plication parameters in engineering units and then
provide performance limits and graphs, configura-
tion resistor values, and jumper settings for use with
the iC-TW8 TW8_1D demonstration board. This
greatly simplifies and speeds up the design process
of encoders using the iC-TW8.
Pin configuration allows selection of only the most
commonly used features of the device. Access to all
features of the iC-TW8 is available in serial config-
uration mode, described in a separate document.
Functional Overview
The iC-TW8 is a general-purpose 16-bit Sin/Cos
interpolator with sophisticated auto-calibration
functions. It accepts 20mV to 1.4V peak-to-peak
differential analog input signals from magnetic or
optical sensors and calculates (interpolates) the an-
gular position. Output is industry-standard incre-
mental AB quadrature at programmable resolution.
Simple pin configuration and one-step automatic
calibration requires no complicated signal analysis
or calibration procedure during product design or
production.
In addition to the chosen sensor, the iC-TW8 re-
quires an external EEPROM to store its configura-
tion and calibration data. An external crystal can be
used instead of the internal oscillator of the iC-TW8
for superior frequency stability. A differential line
driver can be connected directly to the iC-TW8
quadrature outputs to make a complete encoder.
COS
SIN
OUTA
OUTB
Interpolation factor of x5 shown
ZERO
OUTZ
Index pulse is suppressed
as ZERO is low.
Figure 1: iC-TW8 Functional Overview
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