AET-Series TMR Linear and Off-Axis Rotational Encoder Sensors
NVE’s AET-Series sensor elements are versatile, wide-airgap sensors typically used with multipole ring magnets, both radial and face poles, and magnetic linear scale. Standard spacing sensors can detect pole pitches from 0.5 mm to 5 mm. The sensors are Wheatstone bridges comprised of tunneling magnetoresistance (TMR) elements. Both full-bridge and half-bridge versions are available.
The AETxxxF full-bridge sensors offer excellent noise immunity and large differential output signals, and they fully cancel common-mode interference fields. AETxxx half-bridge sensors combine high performance with a half-bridge outputs interface, ideal for simplicity and miniaturization. They can be influenced by common-mode magnetic fields above 1 millitesla.
| AET-Series TMR Encoder Sensors | ||||
|---|---|---|---|---|
| Part Number | Half or Full Bridge | Pole Pitch (normal mode) | Pole Pitch (double pitch mode) | Package |
| AET500-02E | Half | 5 mm | N/A | SOIC8 |
| AET050F-00E | Full | 0.5 mm | 1 mm | MSOP8 |
| AET075F-00E | Full | 0.75 mm | 1.5 mm | MSOP8 |
| AET100F-00E | Full | 1 mm | 2 mm | MSOP8 |
| AET120F-00E | Full | 1.2 mm | 2.4 mm | MSOP8 |
Magnetic Pitch and Pole Pitch
The AET-Series are linear sensors designed for detecting multipole magnets for off-axis rotational or linear scale applications. The TMR sensor elements are bipolar, meaning they detect both north and south magnetic fields.
AET-Series sensors are named based on the north-south “pole pitch” they are optimized to detect. The sensor’s sine and cosine outputs are periodic with the “magnetic pitch.” As an example, to detect a magnetic strip with “pole pitch” (specified by the manufacturer) of 1 mm, choose AET100F-00E. The sensor provides sine and cosine output signals, with a full cycle occurring every 2 mm.
Other common configurations for the AET-Series are illustrated below, where the same comments about “pole pitch” and “magnetic pitch” apply. The sensor output amplitude scales approximately linearly with airgap, reaching the maximum value when the sensor face is at the magnet face. The outputs scale ratiometrically with the supply voltage.
Evaluation Kits
An evaluation kit is available for the AET-Series sensors. NVE also offers a linear magnetic scale demonstration featuring the AET500-02E sensor.
The AG970-07E Evaluation Kit helps with testing a variety of AET-Series sensors with linear magnetic scales. The kit includes:
- All five AET-Series parts (unsoldered in tubes)
- A 3 x 4-inch (76 x 101 mm) PCB with test points and screw terminals
- Detachable fixturing for linear magnetic tape (tape sold separately)
The AG965-07E demonstration kit showcases micron precision with an AET500-02E sensor. The kit includes:
- A 3 x 5-inch (76 x 127 mm) PCB
- An AET500-02E 5 mm pole-pitch sensor
- A four digit position display
- Part #12592 5mm pole pitch magnetic tape
- 3-D printed fixturing
- LEDs for pole detected
- Powered by three AAA batteries (included)
NVE also sells linear scale magnets that can be used with AET-Series sensors:
| Part Number | Pole Pitch | Typical Flux Density @ Airgap |
|---|---|---|
| 12589 | 0.5 mm | 20 mT @ 0.2 mm |
| 12590 | 1 mm | 20 mT @ 0.4 mm |
| 12591 | 2 mm | 30 mT @ 0.7 mm |
| 12592 | 5 mm | 30 mT @ 1.4 mm |
AET500 Magnetic Linear Encoder Demonstration
TMR Noncontact Magnetic Encoders