AS8221

FlexRay Standard Transceiver

www.austriamicrosystems.com/flexray/AS8221

Revision 1.1

1 - 43

Data Sheet

1 General Description

This document is subjected to change without notice.

The AS8221 is a high speed automotive bus driver fully conforming

to the FlexRay Electrical Physical Layer Specification V2.1 Rev B.

The AS8221 operates as a bi-directional interface between the

FlexRay Communication Controller and the twisted-pair copper

wiring.

The AS8221 provides an optimized host controller interface

consisting of three low-active pins. The Enable (EN) and Standby

(STBN) input pins for mode handling by the microcontroller and the

Error (ERRN) out pin where system, chip failures or status

information are signalled to the microcontroller. Signalling logic high

on the Enable and Standby pin the device will enter NORMAL mode

in case no fault condition is given and in this mode the device is fully

operational meaning FlexRay communication is possible.

Additionally a RECEIVE-0NLY mode is implemented, which can be

accessed by the microcontroller where only FlexRay streams can be

received in order to avoid unwanted disturbances on the FlexRay

bus while listening to the bus traffic. In the low-power modes

(STANDBY and SLEEP mode) very low power consumption is

achieved.

(either STANDBY or SLEEP mode) and the device will signal an

operation is possible. A safe mechanism from the low-power modes

to POWER-OFF mode and vice versa is implemented ensuring that

no deadlock can happen during the startup phase.

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

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.

The symmetrical transient control for the high- and low-side driver for

both the bus-minus (BM) and bus-plus (BP) line allows an ideal

balance of communications over different network topologies, with

excellent EMC performance.

2 Key Features

Compliant with FlexRay Electrical Physical Layer Specification

V2.1 Rev. B

Data transfer up to 10 Mbps

Excellent EMC performance. High common mode range ensure

excellent EMI

Interface for Bus Guardian or supervision circuits

Automatic thermal shutdown protection

Supports 12V and 24V systems with very low sleep current

Integrated power management system

- Two inhibit pins for external voltage supply control

- Local wake-up input

- Remote wake-up capability via FlexRay bus in low-power

modes

Supports 2.5, 3, 3.3, 5 V microcontrollers, automatic adaptation

to digital interface levels

Protection against damage due to short circuit conditions on the

bus (positive and negative battery voltage)

Operating temperature range -40ºC to +125ºC

Lead-free SSOP20 package

3 Applications

The AS8221 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 (clamp 30). The AS8221 can be used as only ECU wake-up

component with very low power consumption in SLEEP mode.