Electronics Weekly
Edge rate up to 4.5MHz are possible, equating to 4,170rpm at 16bits, and up to 33,000 position sample/s.
“33,000 measurements per second is over six times faster than our previous fastest processor, the CAM502,” company CEO David Ely told Electronics Weekly. “This was extremely hard to do well.”
The part, CAM622, uses resonant induction between two PCBs, one the stationary sensor on which the chip is mounted, and the other a rotating target that carries only two ceramic capacitors and a specific pattern of tracks.
Tuning to the appropriate operating frequency is automatic over ±8%.
The PCBs are called ‘Type B Rotary Sensor’ and ‘Type B Rotary Target’ (right) if bought from the company, from which they are available in three nominal sizes: 25, 30 or 50mm diameter, with centre holes of 8.6, 13.6 or 31mm respectively.
“The output is stable to within 0.01° across temperature range -40 to +125°C with 25mm B3 Rotary Sensor,” according to the company. The same sensor also “achieves better than ±0.14° linearity error when the gap between sensor and target is between 0 and 2mm, with ±0.3mm radial and ±0.3° tilt misalignments.”
Customers can also create their own sensor and target PCBs.
Output format is ‘ABN’ – quadrature plus a reference pulse.
“CAM622 ensures that ABN edges emulate those generated by an ideal optical encoder,” claimed CambridgeIC, adding: “This means it can replace optical encoders, eliminating any accompanying bearings, seals and housings.”
Alternatively the IC’s SPI can be used as its primary interface with a host processor.
This serial bus is also used for programming on-board non-volatile memory that store configuration for stand-alone operation.
There is an evaluation board for prototyping, and the company’s ‘Streaming Adapter’ is available for programming, which connects the IC to a USB port on a PC running ‘CAM622 Configuration Tool’ software.
Operation is over 3.1 to 3.6V and -40 to +125°C.
CambridgeIC is a fabless chip company headquartered in Cambridge UK.
