Optical sensors iC-LTA and the iC-PT supply incremental and commutation signals in the smallest possible design space, claims IC Haus. They are based on a flat optoQFN that is just 0.9 mm thick and with a thin glass lid. The optimised phased array structure means that a minimal scanning area of just 1.9x3.1mm is enough to generate 2,500 pulses from a code disc measuring only 26mm across. The iC-LTA is an unstructured photo array for customised design. It is compatible with the iC-PT sensors which are available in diameters of 26mm (iC-PT2613) and 33mm (iC-PT33xx). Three on-chip scanning tracks replace Hall sensors for motor commutation. The code disc stipulates the signal and can suit the motor pole count. The photocurrent signals are conditioned by low-noise CMOS amplifiers and can be comparated or interpolated twice and output through 4mA push/pull drivers as indexed encoder quadrature signals. Output frequencies of up to 800 kHz are permitted, enabling motors with speeds of up to 20,000 rpm to be controlled (at 2500pulses). Analogue test signals can be activated for assembly and alignment. The small sampling area and a high sensitivity help to reduce the power needed for the LED. The devices control the LED and also compensate for fluctuations in the operating temperature range of -40 to +120°C.
