AS8220 datasheet(14/34 Pages) AMSCO

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AS8220A

Objective Data Sheet - Detailed Description

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. RxD reflects the bus data and reflect the bus state. In this mode, the transmitter state can be selected as

shown in the Table 5. In case the over-temperature flag is set the transmitter is disabled. The bus wires are terminated

to VCC/2 via receiver input resistances.

Table 5. Transmitter State

BGE

TxEN

TxD

Transmitter state

Bus State

If the differential bus voltage is higher than VBUSActivehigh or lower than VBUSActivelow for a time longer than tBUSAc-

tivityDetection, then activity is detected on the bus (Bus = active), 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 lover 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), RxD is switched to logical “high”

STANDBY mode

In this mode the transceiver is not able to send and receive data signals from the bus. The power consumption is

significantly reduced respect the NORMAL mode. The bus wires are terminated to GND (bus state: Idle_LP).

Non Operating Mode

The AS8220A provides the following non operating mode:

Power Off

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

connected to GND (bus state: Idle_HZ).

Undervoltage Events

Undervoltage VIO

When VIO voltage falls below VIOTHL for a time longer than tUV_DETECT then the undervoltage VIO flag is set and it is

reset when VIO exceeds the voltage threshold VIOTHH for a time longer than tUV_REC. The flag can be set or reset in all

the operation modes. The flag is reset at power off.

Undervoltage VCC

When VCC voltage falls below VCCTHL for a time longer than tUV_DETECT then the undervoltage VCC flag is set and it is

reset when VCC exceeds the voltage threshold VCCTHH for a time longer than tUV_REC. The flag can be set or reset in

all the operation modes. The flag is reset at power off.

Enabled

Data1 (BP is driven high, BM is driven low)

Enabled

Data0 (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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