“True 0-Hz” wheel speed sensor ASIC

“True 0-Hz” wheel speed sensor ASIC

shutterstock_276995234The ASIC interfaces with 3 half-bridge TMR (Tunnel Magneto Resistance) sensors to monitor the speed of a rotating magnetized subject, commonly used in automotive safety critical applications like ABS (see picture), electronic parking breaks or hill-hold control.

The design supports True 0-Hz (standstill) functionality upto 20kHz. Automotive compliance is guaranteed through careful EMC/ESD aware design and compliance to ISO pulses. Through an OWI (One-Wire-Interface), this ASIC can be programmed and diagnosed in the field. Low noise, high-gain amplifiers are integrated to support a wide gain range from 1.5V/V to 192V/V.

This mixed-signal ASIC includes on-chip DSP sequencer to distinguish between rotation/vibration while compensating offset and tracking the gain.

Features

  • TMR magnetic sensor (3 half-bridges)
  • Wide input range (5mV to 600mV) with DC offset of 200mV
  • Extremely low jitter output over entire signal range (<0.1%)
  • On-chip DSP to distinguish between rotation/vibration
  • Functional safety ISO26262 ASIL B
  • Miswiring of supply (-18V to +24V)
  • System level ESD pulses (4kV)
  • EMC requirements (EMI,EME, ISO-pulses [7637])
  • One-Wire-Interface (OWI), AK, PWM, current modulation
  • 2- or 4-pins package
  • 0.18um BCD process