IC-PD3948_14 Datasheet, PDF (2/12 Pages) IC-Haus GmbH – PHASED ARRAY SINE ENCODER

iC-PD 3948
PHASED ARRAY SINE ENCODER
preliminary
Rev C1, Page 2/12
DESCRIPTION
iC-PD3948 is an optical sensor IC with integrated
photodiodes whose signal currents are converted
into output voltages by low-noise transimpedance
amplifiers.
Due to a high transimpedance gain of typically 4 MΩ
(*1 MΩ/2 MΩ), output signal voltages of several hun-
dred millivolts are obtained at illumination levels of
just 1 to 3 mW/cm² (*6 to 18 mW/cm²). In most cases
complicated noise suppression measures are thus
rendered unnecessary.
As the pin names would suggest, iC-PD3948 is typ-
ically applied as a sine encoder for motor feedback
systems. To this end, iC-PD3948 provides sine and
cosine signals with both a high resolution of 2048
CPR (plus an additional index signal) and a low res-
olution of 1 CPR (at C/D).
All code disc signal tracks are evaluated differential;
the high resolution sine signals are read by photo-
diodes in a phased array. The layout of the signal
amplifiers is such that there is good paired channel
matching, reducing the time and effort required for
calibration to an absolute minimum.
The spectral sensitivity ranges from visible to near
infrared light, with the maximum sensitivity close to
a wavelength of 680 nm. An output voltage of 1 V is
typical in low light conditions, for instance when iC-
PD is illuminated at only 2 mW/cm² (*12 mW/cm²) by
a 740 nm LED. A relatively low LED current is enough
to operate the sensor, proving beneficial to the life ex-
pectancy of the LED at high operating temperatures.
HD Phased Arrays are designed for fidelity and ro-
bustness. Ultra-low signal distortion is obtained at
increased tolerances for alignment and random code
defects (e.g. due to dust).
For information on chip releases, refer to chapter De-
sign Review.
*) Data refers to chip release iC-PD3948 Y.