Ultra-fast TMR front-end IC enables demanding electric motor applications

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By Christoph Hammerschmidt

TDK Corporation is expanding its TMR sensor portfolio with the new Micronas ASA 2310 signal processing IC for high-speed electric motor applications in automotive and industrial environments. The ASA 2310 is a low-drift, low-noise, customer-programmable front-end IC with differential or single-ended SIN/COS input and analogue outputs. The vendor sees the main areas of application in the commutation of brushless DC (BLDC) and permanent magnet synchronous motors (PMSM) in safety-relevant environments with a long wiring harness between sensor and ECU, in the detection of the rotor position of traction motors in electric vehicles (BLDC, PMSM, PMSR etc) and in the replacement of resolvers. Other applications include use in brake boosters and lidar mirrors.

New rotor position sensing solutions based on the ASA 2310 offer high-resolution and accurate position measurement at very high speeds of up to 650,000 rpm. This can maximise torque and increase efficiency in high-speed motors, which is essential for hybrid and electric vehicles to achieve maximum range. In addition, this sensor solution works independently of the pole pair number of the motor and therefore does not require complex hardware changes – a major advantage over inductive resolver technologies. This offers more flexibility in the development of the hybrid and electric drives of the future.

The ASA 2310 complements TDK’s TAS family of high-precision analogue TMR sensors. The sensors, which are powered and monitored by the ASA 2310, detect the magnetic field direction in the X-Y plane and provide an analogue SIN/COS output voltage that is used as an input signal to the ASA 2310. The sensor interface and signal conditioning of the ASA 2310 are optimised for TMR sensor bridges. Important characteristic values such as gain, offset, (absolute) zero angle and orthogonality can be set via the integrated signal path by programming the non-volatile memory of the ASA 2310. The flexibly selectable gain factors ensure that the device can support various TMR full and half bridges from TDK. The sensor signals amplified by the ASA 2310 are passed to the A/D converters of the electronic control unit (ECU), which can then perform a very accurate calculation of a magnet’s angle of rotation.

With its overvoltage and reverse polarity protection (±18 V), the ASA 2310 offers excellent robustness against electrical interference. Compared to commercially available signal amplifier ICs, the manufacturer says the ASA 2310 is better suited for safety-critical applications because this device simplifies external circuitry. It also reduces the overall system size, number of passive components and the cost of the assembly process.

The ASA 2310 is defined as SEooC (Safety Element out of Context) ASIL B ready according to ISO 26262. To enable the most efficient fault localisation and elimination, the ASA 2310 offers a single point failure metric (SPFM) of more than 97 per cent, exceeding even the standard requirements of an ASIL B classification. If ASIL decomposition is applied at system level, the IC can be integrated into systems up to ASIL D. In addition to various integrated circuit components for monitoring the IC itself as well as the external TMR sensors, the ASA 2310 has an optional and unique self-test that does not require an external magnetic field. This allows the system to test the entire signal path within the device before normal operation begins. In an application setup, the test can be used to verify the integrity of the entire signal path, including electrical connections, external output capacitors and the ECU. Finally, the diversity of safety monitoring helps to increase the diagnostic scope and simplify external safety monitoring on the ECU side.

While the TMR TAS sensors are available in a wide package portfolio (single die, dual die), the ASA 2310 signal processing IC is offered in a very compact 3 mm x 3 mm DFN12 SMD package. A reference evaluation board, consisting of magnet design and sensor as well as signal processing chipset, is available from TDK upon request.

Samples of the device are available now. Start of production is planned for the end of 2023.

More information here


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