TDK introduces high-speed TMR front-end IC

ASA 2310 is a low-drift, low-noise, customer-programmable TMR front-end IC with differential or single-ended SIN/COS inputs and analogue outputs. Samples of ASA 2310 are now available. The start of production is planned for the end of 2023.

The ASA 2310 is designed to interface the high-precision analogue TMR sensors of the TAS family. The sensors, powered and monitored by the ASA 2310, are detecting magnetic-field direction in x-y plane, and providing a SIN/COS analogue voltage output which is used as input for the ASA 2310. The sensor interface and signal conditioning of the ASA 2310 are optimised for the TMR-Bridge signals. Major characteristics like gain, offset, (absolute) 0-angle, and orthogonality can be adjusted using the integrated signal path by programming the non-volatile memory of the ASA 2310. The different coarse gain settings ensure that the device can support various TMR full- and half -bridges from TDK. The amplified single or differential ended output signals of the ASA 2310 can be used to calculate the rotation angle of a magnet with very high accuracy by an external A/D-converter and an electronic control unit (ECU). 

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

With its overvoltage and reverse polarity protection (+/-18V) the ASA 2310 features excellent robustness against electrical challenges. The ASA 2310 is appropriate for safety-critical applications since the signal-conditioning IC simplifies the external circuitry resulting in a low FIT rate. Moreover, the total system size, BOM, and assembly process costs are reduced. 

This product is defined as SEooC (Safety Element out of Context) ASIL B ready according to ISO 26262. To enable the most efficient failure localisation and elimination, the ASA 2310 provides a single-point fault metric (SPFM) of more than 97% which exceeds even the standard requirements of an ASIL B classification. If ASIL decomposition is applied on the system level, the IC can be integrated in systems up to ASIL D. Besides various integrated safety monitoring of the IC itself and the external TMR-bridges, the ASA 2310 features an optional and unique fluxless self-test allowing the system to test the full signal path inside the device before the ordinary operation starts. In an application setup, the test can be used to check integrity of the whole signal path including wiring, external output capacitors and ECU. Finally, the variety of safety monitoring helps to increase diagnostic coverage and simplify the external safety supervision on the ECU side. 

“The ASA 2310 is a high-performance IC that extends the functionalities of a very precise analogue TMR sensor and reduces the influence of noise and parasitic components caused by remote application setups where the sensor module is separate from the ECU and connected by a long wire-harness,” said Frederik Berstecher, Product Marketing Manager for Fast Hall & TMR at TDK-Micronas. “When combining it with TDK’s TMR TAS sensor family, customers can commercially scale their application setups depending on accuracy, EMC or functional safety requirements since the ASA 2310 can operate up to four TMR half-bridge sensors at the same time. Thus, rotor position sensor solutions based on the ASA 2310 can be used for a wide variety of safety-critical applications like power steering, brake boosters, or traction motors.”

Main applications

• Brushless DC (BLDC) and permanent-magnet synchronous motor (PMSM) commutation in a safety relevant environment with long wire-harness between sensor and ECU

• Traction motor rotor position for electric vehicles (BLDC, PMSM, PMSR,…)

• Electric power steering motor

• Replacement of resolvers

• Brake booster

• LIDAR mirror

While the TMR TAS sensors are available in a wide package portfolio (single-die, dual-die), the ASA 2310 signal-conditioning IC is offered in a very compact 3x3mm DFN12 SMD package. A reference evaluation board consisting of magnet design and sensor + signal conditioning chipset is available on request from TDK. 

Main features and benefits

• Support of various TMR full- and half-bridges from TDK

• Various analog output configurations - Differential or single-ended SIN/COS analogue output signals (no demodulation necessary) - Non-ratiometric or ratiometric analogue output related to the supply voltage

• Intrinsic signal conditioning with on-chip calibration and integrated safety monitoring reduce effort on ECU side

• Optimised signal conditioning for TMR signals, like output gain, offset, 0-angle and orthogonality correction

• Integrated, protected supply for the external TMR-bridges

• Fast response time and high output bandwidth for applications up to 650,000 rpm

• Operating supply voltage: 3V to 5.5V

• Absolute maximum supply voltage: ±18V

• Programming via the IC’s output pin. No additional programming pin required

• Low current consumption

• Optimised for automotive environments with a wide ambient temperature range from -40°C to 160°C and integrated protection circuitry with excellent ESD and EMC robustness

• ISO 26262 development: ASIL B ready SEooC (Metrics (PMHF, SPFM, LFM) according to ASIL C)

• Very small DFN12 3x3mm package