The TLE4999I3 sensor IC incorporates two Halls into one device for strictly-regulated automotive applications.

Yesterday, Infineon announced a new dual-channel Hall sensor, the TLE4999I3.

Infineon claims that the sensor is the first in the world to monolithically integrate two Hall sensors for ASIL D automotive systems.

 

The TLE4999I3. Image from Infineon

 

The new sensor joins an extent cast of Infineon linear Hall sensors geared primarily towards angular and linear position sensing. In all, Infineon now lists 19 linear Hall products, four of which are labeled as "dual linear Hall" ICs that are for "functionally safe systems". The new TLE4999I3, however, is the only one listed as being "fully ISO 26262-compliant" in the list of linear Hall ICs.

Meanwhile, Infineon's XENSIV family of sensors includes a wide array of magnetic, pressure, radar, and MEMS sensors for an equally wide array of applications from drone position sensing to current flow sensing.

But what does it mean to be fully ISO 26262-compliant—and what does ASIL D mean, anyway?

 

What Is ASIL D?

ASIL stands for automotive safety integrity level. This is a classification system that is based on the ISO 26262 standard, but which sprung from the IEC 61508 standard. The ISO 26262 standard, for its part, concerns itself with the functional safety of road vehicles, a notoriously rugged and safety-focused application. It was revised in 2018 to become ISO 26262:2018.

ASIL D classification represents the strictest level with the highest requirements where A classification is the lowest (aside from a fifth level that denotes a lack of hazard). According to a 2016 Arm presentation on safety and security for automotive SoC design, ASIL D indicates a signal point failure mode (SPFM) of 99% and a latent fault metric (LFM) of 90%.

Because of ASIL D's intensive requirements, it has been a prized classification for electrical components. This is likely why Infineon has highlighted the release of the TLE4999I3 as significant.

 

The XENSIV TLE4999I3 Sensor

The XENSIV TLE4999I3 sensor is actually two Hall sensors in a monolithic device. This incorporation of two sensing elements into one package makes it resilient to failure and also more accurate due to redundant measurement channels. Each channel is independently programmable via EEPROM.

According to the device's datasheet, the TLE4999I's two Halls—referred to as the main Hall probe and sub Hall—produce separate measurement channels, each with independently regulated analog supply domains and biasing units.

 

This diagram conveys the relationship between an external magnetic field and the output signals produced by the two Hall element–based measurement channels. Image from the datasheet

 

The analog signals are then fed to again separate ADCs ("HADC" for the main element, a multiplexed "sub HTS-ADC" for the sub element) which then transmit signals into two DSPs. The DSPs then calculate Hall measurement values based off of compensation parameters (i.e., stress and temperature drift) and provide "a digital Manchester-encoded current modulation signal" which is compatible with PSI5 (Peripheral Sensor Interface 5) v2.1. 

 

Simplified block diagram of the XENSIV TLE4999I3. Image from the datasheet

 

Notable features of the TLE4999I3 include:

  • Operating junction temperature range of -40°C to 150°C
  • 5.5 to 7 V supply-voltage range
  • Two-wire bidirectional SICI (serial inspection and configuration) interface
  • AEC-Q100 qualified
  • Provided in a three-pin leaded PG-SSO-3-12 package ("for mounting in PCB-less modules")

 


 

Have you worked on a project that required ASIL D classification? How about designing components striving for it? Tell us about it in the comments below.

 

Featured image created with resources used courtesy of Vraj Shah and Infineon.

 

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