Tiny encoder saves PCB space, cuts cost

San Jose, Calif. — Avago Technologies has claimed the industry’s smallest three-channel reflective encoder. The AEDR-850x encoders feature built-in interpolation for high-resolution measurement, which is suitable for a wide range of applications, including closed-loop stepper motors, miniature motors, printers, copiers, card readers, insulin pumps and other types of industrial, consumer and medical equipment.
A standard reflective encoder module contains two digital output channels for direction sensing, with another module required for indexing purposes. For motion feedback applications requiring high-resolution measurement, an external interpolation device had previously been necessary.

The Avago AEDR-850x reflective encoders integrate an LED light source, photodetecting and interpolator circuitry, and the three channels in a single package with a 3.95-mm x 3.40-mm footprint. With high resolution encoding of 304 lines per inch (12 lines per mm), the highly-integrated modules enable a new level of miniaturization for applications where size and space are primary concerns, said Avago.

The AEDR-850x encoders offer interpolation of up to 4X and enable various resolution designs by changing the codewheel size. The optical-based modules are significantly less susceptible to EMI compared with Hall Effect devices, according to Avago. With an absolute operating temperature range of -20°C to 85°C, the rugged encoders are suitable for commercial and industrial operation environments.

Pricing: The AEDR-8500 reflective encoder is gated 90°, the AEDR-8501 encoder is gated 180° and the AEDR-8502 encoder is ungated 360°. The encoders are priced at $6.75 each in quantities of 100. Samples and production quantities will be available in April 2011.