AS8221_V3 datasheet, PDF - EEWORLD Datasheet

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AS8221_V3: DescriptionFlexRay™ Standard Transceiver; Package Type: SSOP-20; Temperature Range: -40 - +125 °C; Automotive Qualification: X; Categoryaccessories; File Size516KB，42 Pages; ManufacturerAMS; Websitehttps://ams.com/zh

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AS8221_V3 Overview

FlexRay™ Standard Transceiver; Package Type: SSOP-20; Temperature Range: -40 - +125 °C; Automotive Qualification: X

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AS8221

F l e x R a y S t a n d a r d Tr a n s c e i v e r

1 General Description

This document is subject 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-ONLY 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.

In case of undervoltage at one of the supply voltages (V

BAT

, V

and V

) 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 V

BAT

and V

the device will enter the POWER-OFF mode, where no

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 2.5V, 3V, 3.3V, 5V 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.

www.ams.com/flexray/AS8221

Revision 1.8

1 - 42

AS8221

Datasheet - C o n t e n t s

Contents

1 General Description ..................................................................................................................................................................

2 Key Features.............................................................................................................................................................................

3 Applications...............................................................................................................................................................................

4 Pin Assignments .......................................................................................................................................................................

4.1 Pin Descriptions....................................................................................................................................................................................

5 Absolute Maximum Ratings ......................................................................................................................................................

6 Electrical Characteristics...........................................................................................................................................................

7 Typical Operating Characteristics ...........................................................................................................................................

8 Detailed Description................................................................................................................................................................

8.1 Block Description................................................................................................................................................................................

8.2 Events.................................................................................................................................................................................................

8.3 Operating Modes ................................................................................................................................................................................

8.3.1

8.3.2

8.3.3

8.3.4

8.3.5

NORMAL Mode .........................................................................................................................................................................

RECEIVE-ONLY Mode ..............................................................................................................................................................

STANDBY Mode........................................................................................................................................................................

GO-TO-SLEEP Mode ................................................................................................................................................................

SLEEP Mode .............................................................................................................................................................................

8.4 Non Operating Mode ..........................................................................................................................................................................

8.5 Undervoltage Events ..........................................................................................................................................................................

8.4.1 POWER-OFF............................................................................................................................................................................. 15

8.5.1 Undervoltage/Voltage Recovery V

BAT

...................................................................................................................................... 16

8.5.2 Undervoltage/Voltage Recovery V

......................................................................................................................................... 16

8.5.3 Undervoltage/Voltage Recovery V

........................................................................................................................................ 16

8.6 Power On/Off Events..........................................................................................................................................................................

8.7 Wake-Up Events.................................................................................................................................................................................

8.7.1 Remote Wake-Up Event ............................................................................................................................................................ 16

8.7.2 Local Wake-Up Event ................................................................................................................................................................ 17

9 Application Information ...........................................................................................................................................................

9.1 Fail Silent Behavior.............................................................................................................................................................................

9.1.1 RxEN / BGE timeout .................................................................................................................................................................. 19

9.1.2 State Transitions due to Undervoltage Detection ...................................................................................................................... 19

9.1.3 State Transitions due to Voltage Recovery Detection ............................................................................................................... 19

9.2 Mode Transitions ................................................................................................................................................................................

9.2.1 Operating Mode Transitions ...................................................................................................................................................... 20

9.2.2 ERRN Signalling ........................................................................................................................................................................ 22

9.3 Loss of Ground ...................................................................................................................................................................................

9.4 Error Flags..........................................................................................................................................................................................

9.4.1

9.4.2

9.4.3

9.4.4

9.4.5

9.4.6

Undervoltage .............................................................................................................................................................................

Bus Error (BUSERR) .................................................................................................................................................................

Short Circuit between BP and BM (BP_BM)..............................................................................................................................

Over Temperature (OT) .............................................................................................................................................................

TxEN_BGE Timeout (TxEN_TO)...............................................................................................................................................

Error Flag (ERROR) ..................................................................................................................................................................

www.ams.com/flexray/AS8221

Revision 1.8

3 - 42

AS8221

Datasheet - C o n t e n t s

9.5 Status Flags........................................................................................................................................................................................

9.5.1 Local Wake Flag (LWAKE) ........................................................................................................................................................ 23

9.5.2 Remote Wake Flag (RWAKE) ................................................................................................................................................... 23

9.5.3 Power on Flag (PWON) ............................................................................................................................................................. 23

9.6 Error Flags and Status Flags Read-Out .............................................................................................................................................

9.7 Bus Driver...........................................................................................................................................................................................

9.8 Transceiver Timing .............................................................................................................................................................................

9.9 Transmitter..........................................................................................................................................................................................

9.10 Receiver ...........................................................................................................................................................................................

9.6.1 Error and Status Flag Bit Order ................................................................................................................................................. 24

9.7.1 Bus States ................................................................................................................................................................................. 24

9.10.1 Bus Activity and Idle Detection (only in NORMAL and RECEIVE-ONLY mode) ..................................................................... 28

9.10.2 Bus Data Detection (only in NORMAL and RECEIVE-ONLY mode)....................................................................................... 28

9.10.3 Receiver Test Signal................................................................................................................................................................ 29

9.11 Test Circuits ......................................................................................................................................................................................

9.12 Application Circuits ...........................................................................................................................................................................

10 Appendix...............................................................................................................................................................................

10.1 FlexRay Functional Classes .............................................................................................................................................................

10.2 FlexRay Parameter Comparison ......................................................................................................................................................

11 Package Drawings and Markings..........................................................................................................................................

12 Ordering Information.............................................................................................................................................................

www.ams.com/flexray/AS8221

Revision 1.8

4 - 42

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