Bourns has introduced the Model PER40, a 22 mm low-profile incremental ring encoder for human-machine interfaces where panel depth, tactile control and reliable digital position sensing must be balanced.
The mechanical encoder combines continuous rotation, detent feedback and a 2-phase quadrature output for industrial controls, instruments and compact appliance interfaces.
Key features and benefits
- 22 mm ring-style, low-profile construction supports compact front-panel and control-interface designs where available installation height is limited.
- 2-phase quadrature output enables a microcontroller or embedded controller to determine incremental movement and rotation direction from the phase relationship of the two output signals.
- 15 pulses per revolution provide incremental control resolution, while 30 detents per revolution give the operator a tactile step approximately every 12 degrees of rotation.
- Continuous 360-degree electrical and mechanical travel allows knob-like adjustment without an end stop, which is useful for menu navigation, parameter selection and repeated setpoint changes.
- 3.3 VDC to 5 VDC operation supports direct integration with common low-voltage digital-control platforms.
- 30,000-cycle rotational life is specified for equipment subject to frequent operator interaction.
- RoHS compliance supports use in products designed around applicable environmental material restrictions.
Technical highlights
| Parameter | Bourns Model PER40 specification |
|---|---|
| Encoder type | Incremental mechanical ring encoder |
| Ring diameter | 22 mm |
| Output | 2-phase quadrature code |
| Rated voltage | 3.3 VDC to 5 VDC |
| Contact rating | 0.3 mA to 1 mA |
| Resolution | 15 pulses per 360-degree rotation |
| Tactile feedback | 30 detents per revolution |
| Electrical travel | Continuous |
| Mechanical angle | Continuous 360 degrees |
| Sliding bounce | 3 ms maximum |
| Operating and storage temperature | -40 °C to +85 °C |
| Insulation resistance | 100 Mohm minimum at 250 VDC |
| Dielectric strength | 300 VAC for 1 minute at sea level |
| Ingress-protection rating | IP40 |
| Rotational life | 30,000 cycles |
The PER40 is a contacting encoder, so its output is intended for low-level control signalling rather than for switching load current. The specified sliding bounce of up to 3 ms means firmware should apply suitable debouncing before accepting a change of state as a valid incremental movement.
Typical applications
Bourns identifies the PER40 for the following interface applications:
- Industrial automation control panels
- Industrial tools
- Test and measurement equipment
- Home-appliance instrumentation
The combination of ring geometry and continuous rotation can suit compact operator panels where a conventional protruding shaft control would add unwanted depth or mechanical exposure. Its tactile detents provide immediate operator feedback without requiring the user to look continuously at a display.
Application fit
| Design requirement | How the PER40 fits |
|---|---|
| Compact front panel | The 22 mm low-profile ring format is intended to help reduce panel height and mechanical depth |
| Menu navigation or setpoint adjustment | Quadrature output enables directional incremental input to a digital controller |
| Tactile operator control | Thirty detents per revolution provide distinct mechanical indexing points |
| Repeated manual adjustment | Continuous rotation avoids mechanical end stops during repetitive navigation |
| Industrial ambient conditions | The specified -40 °C to +85 °C operating range supports a broad industrial temperature envelope |
| Protected-enclosure use | IP40 indicates protection against solid objects larger than 1 mm, but not against water ingress |
Design-in notes for engineers
- Decode both quadrature phases. A controller should sample both encoder outputs so that it can distinguish clockwise from counter-clockwise movement and apply the intended count multiplier in firmware.
- Implement switch debouncing. The maximum 3 ms sliding-bounce specification should be accommodated in firmware or hardware filtering. Validate the selected debounce interval against the actual interaction speed and the required user-interface responsiveness.
- Respect the low contact-current range. The stated 0.3 mA to 1 mA contact rating makes the device appropriate for logic-level sensing; designers should not assume it is suitable for direct switching of LEDs, relays or other loads.
- Review mechanical integration early. Confirm panel cut-out, mounting, ring accessibility, adjacent-control clearance and the required tactile operating force according to the manufacturer datasheet.
- Consider environmental sealing at system level. The IP40 rating does not provide water protection. Equipment exposed to washdown, condensation, outdoor weather or conductive dust may require additional front-panel sealing or a different encoder technology.
- Verify the expected duty profile. The 30,000-cycle rotational-life rating should be compared with the anticipated number of user adjustments over the equipment service life, including commissioning and maintenance use.
Further reading
- Potentiometers, Encoder, Rheostats and Trimmers
- Bourns Expands 12 mm SMD Incremental Encoder with Shaft-Length Options for Compact HMI Controls
- Bourns Unveils High Reliability Compact Micro Encoders
- Passive Components for Industrial Automation and Robotics (Dossier Report 08/26)
Source
This article is based on the Bourns press release covering the Model PER40 low-profile incremental ring encoder. Engineers should consult the current manufacturer datasheet and associated documentation for final component qualification, mechanical integration and design release.
