AN602 - Vishay Siliconix

AN602 Driver ICs

ISO 9141 is an international standard for communications between automobiles and diagnostic testers. It specifies a serial data communication bus between the vehicle’s Electronic Control Units (ECUs) and the diagnostic test SAE OBDII Scan Tool (SAE J 1978). ISO 9141 has been adopted by the California Air Resources Board for all cars sold in California with .

Features

V), which exceed ISO 9141 (
  –1 V to 40 V). The Drivers The Si9241AEY (Figure 2) is designed for the user that needs only K-Line communication. The ECU controls the K output through Transmit Pin (Tx) and Chip Select Bar (CS). The fault detection circuitry monitors Tx and K to determine open and shorted loads. If K is high when Tx is low, the K-Line is shorted. Conversely, if K is low when Tx is high, the K-Line is open. Over-temperature protection is always enabled, so a fault is determined whenever the junction temperature exceeds 150_C. All faults are latched until chip select bar is set high.