Motion System Design
Speck-sized motor encoder

Speck-sized motor encoder

A standard reflective encoder module contains two digital output channels for direction sensing, but needs another module for indexing. Similarly, motion feedback applications requiring high-resolution measurement necessitate an external interpolation device.

Now there's unprecedented miniaturization with an encoder that integrates three channels — plus an LED light source, photodetecting, and interpolator circuitry — in a single 3.95 × 3.40-mm footprint. This reflective encoder from Avago Technologies, San Jose, Calif., is called the AEDR-850x and features built-in interpolation for high-resolution measurement on closed-loop stepper motors, miniature motors, printers, copiers, card readers, insulin pumps, and other industrial, consumer, and medical equipment where size and space are limited.

The AEDR-850x units encode 304 lines per inch and offer 4x interpolation. Myriad resolutions are possible by changing the codewheel size, and the optical-based modules are significantly less susceptible to EMI compared with Hall effect devices.

On display: AEDR-850x encoder

Key features: Small surface-mount leadless 3.95 × 3.40 × 0.95 mm package; TTL compatible, allowing outputs interfacing directly to most signal-processing circuitries; 1x, 2x, and 4x interpolation selectable via external pinouts; single 5-V supply; absolute operating temperature range of -20° to 85° C

What it means to you: Compact encoder's integrated third channel and high resolution enable a smaller motor encoding system than ever before — to cut design costs and save PCB board space for industrial automation and medical applications.

What else: 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 $6.75 each in quantities of 100; samples are available.

Innovator: Avago Technologies • (800) 235-0312 •

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