IC-TW4 Datasheet, PDF (2/14 Pages) IC-Haus GmbH – PROGRAMMABLE INTERPOLATOR WITH AUTOMATIC OFFSET CORRECTION

iC-TW4 PROGRAMMABLE INTERPOLATOR
WITH AUTOMATIC OFFSET CORRECTION
Rev D1, Page 2/14
DESCRIPTION
iC-TW4, operating on single-ended supplies of 3.3 V
to 5 V, is a low cost interpolation device featuring
an automatic signal conditioning and differential en-
coder quadrature outputs for cable drive.
The chip is pin configured with four external resis-
tors and needs no micro controller or EEPROM for
operation or configuration. An adaptive algorithm is
used to automatically cancel sensor and input ampli-
fier offset voltages, therefore eliminating the need for
cumbersome system calibration.
The pin configuration selects for the interpolation be-
tween factors of x2 and x64, and adapts the input
gain to cope with differential sensor signals between
10 mVpp to 1.5 Vpp.
The interpolation engine accepts two differential si-
nusoidal input signals (sine and cosine) to produce a
highly interpolated incremental output signal. Sensor
bridges are directly interfaced with no external com-
ponents required.
iC-TW4 can also operate on single-ended input sig-
nals when tying the negative input terminals to the
signal reference, usually VDD/2.
The index gating inputs can interface a wide range of
index sensors, a Hall switch or MR bridge sensor, for
instance. iC-TW4 generates the index pulse for every
sine/cosine signal period that is released by the gat-
ing signal. The pulse output is one increment wide
and is located at the positive crossover of the A ver-
sus the B inputs. By swapping pins PINA and NINA
or pins PINB and NINB it is possible to achieve any
desired phase relationship of the Z output versus the
A and B outputs, respectively.
The device also supports a variety of test modes
for device verification and production test. A built
in power-on-reset circuit keeps the device in reset
mode until the applied power supply voltage permits
reliable operation.
CONTENTS
PACKAGES
ABSOLUTE MAXIMUM RATINGS
THERMAL DATA
ELECTRICAL CHARACTERISTICS
INPUT STAGE
Programmable Gain Amplifier . . . . . . . . .
Automated Offset Adjustment . . . . . . . . .
Limits of Automated Offset Adjustment . . . .
3 CONFIGURATION
8
Interpolation . . . . . . . . . . . . . . . . . . 8
4
Performance . . . . . . . . . . . . . . . . . . 9
Amplification . . . . . . . . . . . . . . . . . . 9
4
Test Modes . . . . . . . . . . . . . . . . . . . 9
5 _{INDEX GATING}
10
7
Calibration Mode . . . . . . . . . . . . . . . . 11
7 _{START UP}
12
7
7 TYPICAL APPLICATIONS
13