AS8221-ASSP datasheet(28/41 Pages) AMSCO

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AS8221

Datasheet - Application In form atio n

www.austriamicrosystems.com/flexray/AS8221

Revision 1.4

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

If the absolute differential bus voltage is higher than VBUSActiveLow and less than VBUSActiveHigh for a time longer than tBUSIdleDetection, bus Idle is

detected, RxEN and RxD are switched to logical high after a time tBUSIdleReaction.

If the absolute differential bus voltage is higher than VBUSActiveHigh or lower than VBUSActiveLow for a time loner than tBUSActivitiyDetection, bus

Activity is detected, RxEN is switched to logical low and RxD shows the detected bus data according to Table 11 after the time tBUSActivityReaction.

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

If, after activity detection the differential bus voltage is higher than VData1, RxD will be high after a time tBUS_RxD01.

If, after activity detection the differential bus voltage is lower than VData0, RxD will be low after a time tBUS_RxD10.

Figure 16. Receiver Characteristics (BUS

→ RxD, RxEN)

Table 11. Logic Table for Receiver Bus Signal Detection

Receiver Operation Mode

Bus Signals

RxEN

RxD

Normal power modes

(NORMAL and RECEIVE-ONLY mode)

Idle

Data0

Data1

VRxD

VBUS

VBUS_ActiveLow

VData0

VBUS_ActiveHigh

VData1

Data0

Activity

Idle

Data1

Activity

VRxEN

VBUS

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