ATA6629 datasheet(14/26 Pages) ATMEL

14 / 26 page

ATA6629/ATA6631 [DATASHEET]

9165F–AUTO–10/14

Fail-safe Features

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During a short-circuit at LIN to VBattery, the output limits the output current to IBUS_LIM. Due to the power dissipation, the

chip temperature exceeds TLINoff and the LIN output is switched off. The chip cools down and after a hysteresis of Thys,

switches the output on again. RXD stays on high because LIN is high. During LIN overtemperature switch-off, the VCC

regulator is working independently.

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During a short-circuit from LIN to GND the IC can be switched into sleep or Silent mode and even in this case the

current consumption is lower than 30µA in sleep mode and lower than 70µA in silent mode. If the short-circuit

disappears, the IC starts with a remote wake-up.

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Sleep or silent mode: During a floating condition on the bus the IC switches back to sleep mode/silent mode

automatically and thereby the current consumption is lower than 30µA/70µA.

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The reverse current is < 2µA at pin LIN during loss of VBatt . This is optimal behavior for bus systems where some

slave nodes are supplied from battery or ignition.

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During a short circuit at VCC, the output limits the output current to IVCClim. Because of undervoltage, NRES switches

to low and sends a reset to the microcontroller. The IC switches into fail-safe mode. If the chip temperature exceeds

the value TVCCoff, the VCC output switches off. The chip cools down and after a hysteresis of Thys, switches the output

on again. Because of fail-safe mode, the VCC voltage will switch on again although EN is switched off from the

microcontroller.The microcontroller can then start with normal operation.

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Pin EN provides a pull-down resistor to force the transceiver into recessive mode if EN is disconnected.

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Pin RXD is set floating if VBatt is disconnected.

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Pin TXD provides a pull-up resistor to force the transceiver into recessive mode if TXD is disconnected.

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After switching the IC into normal mode the TXD pin must be pulled to high longer than 10µs in order to activate the

LIN driver. This feature prevents the bus from being driven into dominant state when the IC is switched into normal

mode and TXD is low.

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If TXD is short-circuited to GND, it is possible to switch to sleep mode via ENABLE after t > tdom.

ATA6629 Datasheet(PDF) 14 Page - ATMEL Corporation