IC-MQF Datasheet, PDF (2/37 Pages) IC-Haus GmbH – PROGRAMMABLE 12-BIT Sin/Cos INTERPOLATION IC WITH RS422 DRIVER

iC-MQF PROGRAMMABLE 12-BIT ^preliminary
Sin/Cos INTERPOLATION IC WITH RS422 DRIVER
Rev A1, Page 2/37
DESCRIPTION
Interpolator iC-MQF is a non-linear A/D converter
which digitizes sine/cosine sensor signals using a
count-safe tracking conversion principle with se-
lectable resolution and hysteresis. The angle reso-
lution per sine period can be set using SELRES; up
to 4000 angle steps are possible (see page 27).
The angle position is output incrementally by differ-
ential RS422 drivers as an encoder quadrature signal
with a zero pulse or, if selected, as a counter signal
for devices compatible with 74HC191 or 74HC193.
The zero pulse is generated electronically when an
enable has been set by the X1/X2 inputs. This pulse
can be configured extensively: both in its relative po-
sition to the input signal with regard to the logic gating
with A and/or B and in its width from 90° to 360° (1/4
to 1 T).
A preselectable minimum transition distance ensures
glitch-free output signals and prevents counting er-
rors which in turn boosts the noise immunity of the
position encoder.
Programmable instrumentation amplifiers with se-
lectable gain levels allow differential or single-ended,
referenced input signals; a external reference can be
used via input X2 as reference voltage for the offset
correction.
The modes of operation differentiate between high
impedance (V modes) and low impedance (I modes).
This adaptation of the iC to voltage or current signals
enables MR sensor bridges or photosensors to be di-
rectly connected up to the device. The optical scan-
ning of low resolution code discs is also supported by
the reference function of input X2; these discs do not
evaluate tracks differentially but in comparison with a
reference photodiode.
tical encoders via the integrated 50 mA driver stage
(output ACO). If MR sensors are connected this
driver stage can also track the power supply of the
measuring bridges. By tracking the sensor energy
supply any temperature and aging effects are com-
pensated for, the input signals stabilized and the ex-
act calibration of the input signals is maintained. This
enables a constant accuracy of the interpolation cir-
cuit across the entire operating temperature range.
If control limits are reached, these can be indicated
at the maskable error pin ERR. Faults such as over-
drive, wire breakage, short circuiting, dirt or aging,
for example, can be logged.
iC-MQF includes extensive self-test and system di-
agnosis functions which check whether the sensor
is working properly or not. For all error events the
user can select whether the fault is indicated at the
pin ERR or whether the outputs should shutdown. At
the same time errors can be stored in the EEPROM
to enable failures to be diagnosed at a later stage.
For encoder applications the line count of the code
disc, the sensor signal regarding signal level and fre-
quency and the operating temperature can be moni-
tored, for example, the latter using an adjustable on-
chip sensor.
Display error pin ERR is bidirectional; a system fault
recognized externally can be recorded and also reg-
istered in the error memory.
iC-MQF is protected against reverse polarity and of-
fers its monitored supply voltage to the external cir-
cuit, thus extending the protection to the system (for
load currents up to 20 mA). Reverse polarity protec-
tion also covers the short-circuit-proof line drivers so
that an unintentional faulty wiring during initial opera-
tion is tolerated.
The integrated signal conditioning unit allows signal
amplitudes and offset voltages to be calibrated ac-
curately and any phase error between the sine and
cosine signals to be corrected. The channel for the
zero signal can be configured separately.
A control signal is generated from the conditioned
signals which can track the transmitting LED of op-
On being activated the device configuration is loaded
via the serial configuration interface from an external
EEPROM and verified with a CRC. A microcontroller
can also configure iC-MQF; the implemented inter-
face is multimaster-competent and allows direct RAM
access.