TLE 6254-3 G

Data Sheet

9

Rev. 2.0, 2005-03-24

Operation Modes, Wake-Up

In addition to the normal operation mode, the TLE 6254-3 G offers a receive-only mode

as well as two low power operation modes to save power during periods that do not

require communication on the CAN bus: sleep mode,

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and Figure 4). Via the control input pins NSTB and ENT the operation modes are

selected by the microcontroller. In the low power modes neither receiving nor

transmitting of messages is possible.

In sleep operation mode the lowest power consumption is achieved. In order to minimize

the overall current consumption of the ECU (electronic control unit) the external voltage

regulator (5 V supply) is deactivated by the INH output in this mode, when connected.

For that purpose the INH output is switched to high impedance. In parallel the CANL line

is pulled-up to the battery supply voltage via the RTL output and the pull-up paths at the

input pins TxD and RxD are disabled from the internal supply.

To enter the sleep operation mode the transition mode “Go-to-Sleep” has to be selected

(Figure 4) for a minimum time

t

can be actively selected. Otherwise the TLE 6254-3 G will automatically fall in sleep

mode because of the not powered microcontroller.

On a wake-up request either by bus line activities or via the WAKE input, the transceiver

is automatically set in

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enabled by the INH output. The WAKE input reacts to both, transition from high to low

voltage level as well as the other way round. To avoid faulty wake-ups due to transients

on the bus lines or the WAKE input circuitry respectively, a certain filter time is

implemented. As soon as

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NERR and RxD outputs, by setting them low. Upon this the microcontroller can activate

the normal operation mode by setting the control inputs NSTB and ENT high.

The

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connected to the INH output will remain active. Wake-up requests via the WAKE pin or

the bus lines are immediately reported to the microcontroller by setting RxD and NERR

low. A power-on condition (

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BAT

pin is supplied) automatically switches the

TLE 6254-3 G to

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In the receive-only mode data on the CAN-bus are transferred to the RxD output, but

both output stages, CANH as well as CANL are disabled. This means that data at the

TxD input are not transmitted to the CAN bus. This mode is useful in combination to a

dedicated network-management software that allows separate diagnosis for all nodes.

A wake-up request in the receive-only mode is only reported at the RxD-output. The

NERR output in this mode is used to indicate a battery fail condition. When entering the

normal mode the

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feature is useful e.g. when changing the ECU and therefore a presetting routine of the

microcontroller has to be started.