IC-LTA_16 Datasheet, PDF (2/15 Pages) IC-Haus GmbH – 6-CH. INCREMENTAL OPTO ENCODER ARRAY

iC-LTA
preliminary
6-CH. INCREMENTAL OPTO ENCODER ARRAY
Rev C1, Page 2/15
DESCRIPTION
iC-LTA represents an advanced optical encoder IC
featuring an array of integrated photosensors evalu-
ated by a fast on-chip interpolation circuit to higher
resolution.
Its typical application are incremental encoders for
motor speed control and commutation. To this end,
the device provides differential A/B tracks, a differ-
ential index track and three more tracks to generate
block commutation signals.
The optical radius and the native cycles per revolu-
tion (CPR) can be freely determined by the applied
code design, i.e. the code wheel and reticle (applied
externally, or molded to IC as package option). The
adaption to the motor polecount is also carried out by
the code disc, for instance with 4 CPR and 90 degree
phase shift to operate 4-phase brushless motors.
Low-noise transimpedance amplifiers, arranged in a
paired layout to ensure excellent channel matching,
are used to convert the scanner’s signals into voltages
of several hundred millivolts¹⁾.
Precision comparators with hysteresis generate the
digital signals subsequently, either native or interpo-
lated, which are then output by differential ± 4 mA
push-pull drivers.
The built-in averaging LED power controller with its
40 mA driver permits a direct connection of the en-
coder LED. The received optical power is kept con-
stant regardless of aging effects or changes in tem-
perature.
Various operating modes are selectable at multi-level
input SEL²⁾: digital output with native (x1) or interpo-
lated resolution (x2 or x4), analog output or mixed
analog/digital output; the latter combines an output
of sine/cosine signals with comparated UVW commu-
tation signals. During analog operation the amplified
signal voltages are available at the outputs for inspec-
tion and monitoring of encoder assembly, or to feed
external interplation circuits.
Index gating is also pin-selectable at input T1^{2, 3}: the
options are ungated, respectively T-gated if using in-
terpolated output, B-gated and AB-gated.
The device runs at single-sided supplies from 3.5 V
up to 5.5 V and features a low power consumption.
1_{) Operating point varies by code design applied.}
2_{) For ease of replacement, the pin functions of iC-LTA chip release W are}
backwards compatible to iC-LTA chip release X, and compatible to iC-PT
H-Series devices.
3_{) Pin T1 is not available on the oBGA LSH2C package (AB-gated index}
output is preset).