TLE9222LC datasheet(38/43 Pages) INFINEON

38 / 43 page

Data Sheet

Rev. 1.2

2017-10-17

TLE9222

FlexRay Transceiver

Application information

7.4

Implementation of ECU functional safety concepts

The TLE9222 has been implemented with features for alleviating the development of functional safety

requirements on a system level. The top level objective is to ensure a malfunctioning ECU is put in a safe state,

which for the FlexRay transceiver means no bus disturbance.

This is realized by the Bus Guardian interface, which controls the bus transmitter directly at the driver stages.

The TLE9222 is also implemented with a redundant diagnostic path for detecting the true state of the bus

transmitter. This status is multiplexed back to the ERRN output, which is set “low” when the transmitter is

reliably disabled. By taking advantage of this safety feature, the ECU diagnostic coverage can be increased.

Figure 22

Application diagram

In Figure 22 an application example of an Automotive ECU for safety critical applications is shown. Together

with a Safety MCU Supply IC, e.g. the Infineon TLF35584, that incorporates safe state control functionality, the

BGE input of the TLE9222 is connected to the safe state output. If the Safety Supply IC detects unexpected

behavior at the supply voltages or incorrect MCU behavior through the functional watchdog, the TLE9222

makes sure there is no influence to the FlexRay bus after the BGE input is set “low”. Additionally, the

microcontroller can detect the true state of the transceiver output drivers from the ERRN out, which should

TLE9222_APPLICATION_SAFETY_V01

ECU

VBAT

TLE9222PX

FlexRay

Transceiver

GND

VCC

ERRN

RxD

TxEN

TxD

VIO

STBN

SCSN

BM BP

TLF35584

Multi Voltage Safety

Micro Processor Supply

Application

MicroController

E.g. TC2xx Aurix MCU

QUC

QCO

SCSN

SDO

SCLK

SDI

SS1

VDD

VS1 SW1

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