AS8222 datasheet(21/43 Pages) AMSCO

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AS8222

Datasheet - Detailed Descr i p ti on

www.ams.com/eng/FlexRay/AS8222

Revision 1.0

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7.3.1 NORMAL Mode

In this mode the transceiver is able to send and receive data signals on the bus. TxEN and BGE control the state of the transmitter. INH1 and

INH2 outputs are set high. RxD shows the bus data and RxEN the bus state. The error read out mechanism is enabled. In this mode the

transmitter state can be selected as shown in Table 17. In case the over-temperature flag is set the transmitter is disabled. The bus wires are

terminated to VCC/2 via receiver input resistances.



If the differential bus voltage is higher than VBUSActivehigh or lower than VBUSActivelow for a time longer than tBUSActiveDetection, then activity is

detected on the bus (Bus = active), RxEN is switched to logical “low” and RxD is released.



If after the activity detection, the differential bus voltage is higher than VData1, RxD is high.



If after the activity detection, the differential bus voltage is lower than VData0, RxD is low.



If the absolute differential bus voltage is lower than VBUSActivehigh and higher than VBUSActivelow for a time longer than tBUSIdleDetection, then

idle is detected on the bus (Bus = idle), RxEN and RxD are switched to logical “high”.

7.3.2 RECIEVE-ONLY Mode

In this mode the transceiver has the same behavior as in NORMAL mode but the transmitter is disabled.

7.3.3 STANDBY Mode

In this mode the transceiver is not able to send and receive data signals to and from the bus, but the wake up detector is active. The power

consumption is significantly reduced with respect to the non-low-power operation modes. RxD, RxEN signals the negation of the wake-up flag.

INH1 is set to high. If wake-up flag is set then INH2 is high, otherwise it is floating. The error read out mechanism is not enabled. The bus wires

are terminated to GND (bus state: Idle_LP).

7.3.4 GO-TO-SLEEP Mode

In this mode the transceiver has the same behavior as in STANDBY mode but if this mode is selected for a time longer than tSLEEP and the wake

flag is cleared the device enters into the SLEEP mode.

7.3.5 SLEEP Mode

In this mode the transceiver has the same behavior as in standby mode but INH1 and INH2 are floating.

7.4 Non-Operating Modes

The AS8222 provides the following non-operating mode:



POWER-OFF

7.4.1 POWER-OFF Mode

In this mode the transceiver is not able to operate. RxD, RxEN are set to high and ERRN is set to low. INH1 and INH2 are floating. The bus wires

are not connected to GND (bus state: Idle_HZ).

7.5 Undervoltage Events

The device monitors the following three voltage supplies:



VBAT:Battery supply voltage



VIO: Supply voltage for I/O digital level adaptation



VCC: Supply voltage (+5V)

Table 17. Transmitter States

BGE

TxEN

TxD

Transmitter State

Bus state

Enabled

Data_1 (BP is driven high, BM is driven low)

LLEnabled

Data_0 (BP is driven low, BM is driven high)

Disabled

Idle (BP and BM are not driven)

Disabled

Idle (BP and BM are not driven)

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