TLE7257

Functional Description

Data Sheet

10

Rev. 1.0, 2013-10-16

4.4

Sleep Mode

Sleep mode is a low power mode with quiescent current consumption reduced to a minimum while the device is

still able to wake-up by a message on the LIN bus.

After a power-up event the TLE7257 enters Sleep mode by default. The EN pin has an internal pull-down resistor

and the TLE7257 remains in Sleep mode until the external microcontroller applies a logical “high” signal at the EN

input.

To switch the TLE7257 from Normal Operation mode to Sleep mode, the EN input has to be set to “low”.

Conversely a logical “high” signal on the EN input sets the device directly back to Normal Operation mode (see

Figure 4). The TLE7257 can only enter Sleep mode from Normal Operation mode.

Figure 6

Entering Sleep mode from Normal Operation mode

While the TLE7257 is in Sleep mode the following functions are available:

•

The transmitter is turned off.

•

The receiver is turned off.

•

The BUS output is terminated to

V

•

The RxD output is “high” if a pull-up resistor is connected to the external microcontroller supply.

•

The TxD input is disabled and the internal pull-up current source is switched off.

•

The INH output is switched off and is floating.

•

The bus wake-up comparator is active and will cause transition to Standby mode in case of a wake-up event.

•

In Sleep mode only the power-on reset level of the undervoltage detection is active (see “Undervoltage

Detection” on Page 15).

•

The EN input remains active. A “high” signal on the EN input triggers a transition to Normal Operation mode.

INH: „high impedance“

TxD: „high impedance“

TLE7257_SLEEP_MODE

t

RxD: „high“ or „low“ depending on

the signals on the LIN bus

t

INH

t

Data transmission

t

t

Mode

RxD: “high“ because of external pull-up

resistor to the microcontroller supply voltage

Sleep mode

Normal Operation mode

TxD

RxD

EN