ATA6602 datasheet(13/362 Pages) ATMEL

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4921C–AUTO–01/07

ATA6602/ATA6603

3.3.14

Wake-up Scenarios from Silent to Sleep Mode

3.3.14.1

Remote Wake-up via Dominant Bus State

A falling edge at pin LIN followed by a dominant bus level maintained for a certain time period

BUS) results in a remote wake-up request. The device switches to Pre Normal Mode. The VDD

voltage regulator is activated, and the internal slave termination resistor is switched on. The

remote wake-up request is indicated by a low level at pin RXD to generate an interrupt in the

microcontroller. The watchdog needs a trigger signal from PTRIG or NTRIG within the lead time

D to avoid resets at NRES (see Figure 3-3 on page 9).

3.3.14.2

Local Wake-up via Pin Wake

A falling edge at pin WAKE followed by a low level maintained for a certain time period (T

WAKE)

results in a local wake-up request. The extra long wake-up time (T

WAKE) ensures that no tran-

sients as defined in ISO7637 create a wake-up. The device switches to Pre Normal Mode. The

internal slave termination resistor is switched on. The local wake-up request is indicated by a low

level at pin RXD to generate an interrupt in the microcontroller. The watchdog needs a trigger

signal from PTRIG or NTRIG within the lead time t

D to avoid resets at NRES.

3.3.14.3

Wake-up Source Recognition

The device can distinguish between a local wake-up request (pin WAKE) and a remote wake-up

request (dominant LIN bus state). The wake-up source can be read on pin TXD in Pre Normal

Mode. A high level indicates a remote wake-up request (weak pull down at pin TXD) and a low

level indicates a local wake-up request (strong pull down at pin TXD). The wake-up request flag

(signalled on pin RXD) as well as the wake-up source flag (signalled on pin TXD) are reset

immediately, if the microcontroller sets pin EN to high (see Figure 3-3 on page 9 and Figure 3-4

on page 10).

3.3.15

Fail-safe Features

• During a short circuit at LIN, the output limits the output current to I

BUS_LIM. Due to the power

dissipation, the chip temperature exceeds T

LINoff and the LIN output is switched off. The chip

cools down and after a hysteresis of T

hys, switches the output on again. During LIN

overtemperature switch-off, the V

DD regulator works independently.

• The reverse current at pin LIN is very low (< 3 µA) during loss of V

BAT or GND. This is optimal

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

• During a short circuit at V

DD, the output limits the output current to IVDDn. 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 T

VDDoff, the VDD

output switches off. The chip cools down and after a hysteresis of T

hys, switches the output on

again. Because of Pre Normal Mode, the V

DD 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 k

Ω to V

CC, 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.

• If the WD_OSC pin has a short circuit to GND or the resistor is disconnected, the watchdog

oscillator runs with a high frequency and guarantees a reset in any condition.

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