ATA6621N(2007) データシートの表示（PDF） - Atmel Corporation

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ATA6621N
(Rev.:2007)

LIN Transceiver with 5V Regulator and Watchdog

Atmel Corporation 

Figure 3-6. Wake Up from Sleep/Silent Mode at an Insufficient Falling Edge at Pin LIN

Pre-normal Mode

Normal Mode

LIN Bus

VLIN < VS - 1V and

VLIN > 0.6 VS

TXD

High

Low

RXD

VCC

High

Wake-up filtering time

tWAKE

Silent mode

Low

Pre-normal mode

EN

Node in Silent mode

Regulator Wake-up time

Normal mode

EN High

NRES If undervoltage, switch to Pre-normal Mode

Undervoltage detection active

3.17

Fail-safe Features

• During a short circuit at LIN, 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. During LIN

overtemperature switch-off, the VCC regulator works independently.

• The reverse current at pin LIN is very low (< 3 µA) during loss of VBAT or GND. This is optimal

behavior for bus systems where some slave modes are supplied from battery or ignition.

• During a short circuit at VCC, the output limits the output current to IVCCn. Because of

undervoltage, NRES switches to low and sends a reset to the microcontroller. The IC

switches into Pre-normal 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 Pre-normal mode, the VCC voltage will switch on again although EN is

switched off from the microcontroller. The microcontroller can start its normal operation.

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

disconnected.

• Pin RXD is connected with 5 kΩ to VCC, if VBatt is disconnected VCC is at GND level

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

disconnected.

12 ATA6621N

4887H–AUTO–12/07

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