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 M, output signal voltages of several hundred Millivolts are obtained at illumination levels of just 1 to 3 mW/cm2. In most cases complicated noise suppression measures are thus rendered unnecessary.
As the pin names would suggest, iC-PD3948 is typically 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 PPR (plus an additional index signal) and a low resolution of 1 PPR (at C/D).
All code disc signal tracks are evaluated differentially; the high resolution sine signals are read by photodiodes 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 iCPD is illuminated at only 2 mW/cm2 by a 740 nm LED. A relatively low LED current is enough to operate the sensor, proving beneficial to the life expectancy of the LED at high operating temperatures.
• Incremental sine encoders with commutation information
• Motor feedback encoder
• AC and BLDC motor systems
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