AS8222 FlexRay Transceiver

Description

The AS8222 is a high-speed fault tolerant device operating as interface between a generic FlexRay Communication Controller and the copper wiring. The AS8222 is designed to extend the application range for high speed and safety critical time triggered bus systems in an automotive environment. The bus driver is protected against short circuits to the supply. The AS8222 operates at baudrates up to 10 Mbps and is fully conforming to the FlexRay Electrical Physical Layer Specification V2.1 Rev B.

The AS8222 provides an host controller interface consisting of Enable (EN) and Standby (STBN) input pins for mode handling by the microcontroller and the Error (ERRN) output pin, signalling the failures or status information.

The device supports the NORMAL mode with activated FlexRay bus transmitter and receiver, the RECEIVE_ONLY mode with with activated receiver to avoid unwanted disturbances while listening to the communication and the low-power modes STANDBY and SLEEP with very low-power consumption.

In case of undervoltage at one of the supply voltages (VBAT, VCC, and VIO) the device will change its mode to a low-power mode (either STANDBY or SLEEP mode) and the device will signal an error accordingly. In case of low voltage is detected on both VBAT and VCC the device will enter the POWER-OFF mode.

Ensuring application in safety critical environments a two wire bus-guardian interface is implemented where additional monitoring circuitries on the electronic-control-unit can activate and deactivate (BGE) the transmitter and additionally on the receive enable output (RxEN) in low-power modes the wake conditions and in normal power modes the received FlexRay streams can be monitored.

A thermal sensor circuit with an integral shutdown mechanism prevents damage to the device in extreme temperature conditions.

Key Features

• Data transfer up to 10 Mbps
• Compliant with FlexRay physical layer specification v2.1 rev. B
• Excellent EMC performance
• High common mode range insures excellent EMI immunity
• Interface with optional bus guardian for bus supervision
• Automatic thermal shutdown protection
• Supports 12, 24V systems with low sleep current
• Integrated power management system
• Two INH pins for the external voltage regulators control
• Local wake-up input
• Remote wake-up capability via FlexRay bus in sleep mode
• Supports 2.5, 3, 3.3, 5 V microcontrollers and automatically adapts to interface levels
• Does not disturb the bus line if not powered
• Protected against damage due to short circuit conditions on the bus (positive and negative battery voltage)
• Wide operating ambient temperature range -40°C to +150°C
• Pb Free
• Small Pb-free package: SSOP-20
• Automotive qualified to AEC-Q100, grade 0

Applications

The AS8222 FlexRay Standard Transceiver is best fitting for automotive FlexRay nodes where bus wake-up and voltage regulator control for voltage supplies is needed.

The device addresses all ECUs connected to the permanent battery supply (terminal 30). The AS8222 can be used as the only ECU wake-up component with it’s very low-power consumption in SLEEP mode.

The AS8222 FlexRay Enhanced Basic Transceiver is best fitting for automotive control units with a connection to the FlexRay bus.

The device addresses all ECUs connected to the ignition controlled power supply (terminal 15). The AS8222 enables the fast and simple connection to the FlexRay network and supports very low-power consumption in SLEEP mode.

AS8222 FlexRay Transceiver Block Diagram