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L9638

4.5 Sleep mode

This mode allows the lowest current consumption of the transceiver. It'll be reached either by setting the

EN input to LOW (assuming no occurring wake-up event) while being in the normal mode or in case of a

removed short to ground at LIN while being in the short circuit mode.

The INH output will be switched from HIGH to LOW. A further transmission via TxD is prevented. The de-

vice is waiting on any wake-up requests either by LIN (dominant level) or WUP (rising or falling edge). This

will set the device from sleep mode to standby mode. An implemented filter prevents unwished wake-ups

due to occurring glitches or EMI at LIN or WUP.

4.6 Wake-up

The L9638 provides several wake-up conditions from sleep mode:

– Remote wake-up by a dominant level at LIN

– Local wake-up by a falling or rising edge at WUP

– Mode change by setting EN to HIGH

The INH output will be set from LOW to HIGH after each kind of valid wake-up conditions. For remote

wake-up via LIN, RxD will be activated and set as well to a dominant state.

This allows fast reaction for powered

µC with connected interrupt capable receive inputs.

4.7 Fail-safe features

To prevent possible states, that will block the communication line in case of a failed

µC operation, the

L9638 has implemented some special fail-safe features:

– After detected a clear short to ground state at the LIN pin by the protocol handler in the

µC, the trans-

ceiver or the complete power supply of the ECU control logic could be switched off by setting the EN

input from HIGH to LOW. The device will stay in that special short circuit mode until the state of the

LIN bus will switch back from dominant to recessive. No power up or special reset procedures are

required to clear that fail-safe state. L9638 could be reactivated with the usual wake-up signals.

– The TxD and EN inputs support default recessive bus states by internal pull up or down sources

– The output stage of the transmitter is current limited to protect against a shorten LIN to battery

– A thermal shutdown protects the device against over temperature caused destruction. In case of a

permanent overload condition, the output stage will be switched off after reaching the shut down tem-

perature and reactivated after cooling down to the switch on temperature.

– Defined output status in under voltage, loss of Vs or GND condition with no impact to the bus line or

the connected

µC