Electronic Design

Miniscule Absolute Encoder Cuts Assembly Time In Half

This high-speed plug-and-play device, which comes in five resolution options, shaves industrial-automation system costs by 40%.

A novel absolute encoder module that comes in 12- and 16-bit versions uses a modular approach to reduce the number of assembly steps from as many as eight down to just four (see the figure). Agilent Technologies says that its AEAS-7000 is the world's smallest encoder module, measuring 21.4 mm high by 55 mm in diameter. The module also reduces the number of needed components from approximately 80 down to four.

"We use a combination of precision machining and an ASIC chip that contains the signal-conditioning electronics to realize this plug-and-play capability in a small form factor," says Colin Choo of Agilent. "Just four steps are needed to make the absolute encoder: secure the codewheel, slide the module in, secure the module, and remove the alignment clips."

The encoder consists of 13 signal photodiode channels and a single monitor photodiode channel. It features a synchronous 16-MHz true differential pair of sine/cosine outputs over a four-wire serial interface with 1024 periods for unit alignment, as well as a 1-µs cycle time. It has on-chip interpolation and Gray-code correction within ±1 LSB for mounting-tolerance compensation and is accurate to within 16 bits for motions up to 1000 rpm (12 bits up to 12,000 rpm). Plug-and-play eliminates alignment tweaking and manual searching for the LSB and MSB signals. Five encoder resolution options are possible, between 12 and 16 bits.

The unit targets industrial-automation applications, including servo motors, robotics, machine tools, and wafer handlers. Available in August, pricing is under $28 each in 5000-unit lots.

Agilent Technologies

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