TLE7257

Functional Description

Data Sheet

8

Rev. 1.0, 2013-10-16

4.2

Normal Operation Mode

While operating in Normal Operation mode the LIN bus receiver and transmitter are active and support data

transmission rates up to 20 kbps. Data from the microcontroller is transmitted to the LIN bus via the TxD input.

Simultaneously the receiver detects the data stream on the LIN bus and forwards it to the RxD output.

Normal Operation mode can be entered from either Sleep mode (see Figure 9) or from Standby mode (see

Figure 5), by setting the EN input to logical “high”. From Normal Operation mode the TLE7257 can only enter

Sleep mode, it is not possible to enter Standby mode directly (see Figure 4).

The transition time for mode change to Normal Operation mode

t

where the EN pin detects a “high” input signal, and the actual mode change of TLE7257 to Normal Operation

mode.

Figure 5

Entering Normal Operation mode from Standby mode

Table 2

Operation mode transitions

Number

Reason for transition

Comment

1

Power-on detection

The

V

2

Mode change with EN input Triggered by logical “high” level

3

Mode change with EN input Triggered by logical “low” level

4

Mode change with EN input Triggered by logical “high” level

5

Bus wake-up detection

RxD set “low” for signalling the bus wake-up event to the microcontroller

INH: „high impedance“

TxD: „high impedance“

TLE7257_NORMAL_MODE

V

EN,OFF

Standby mode

t

to,rec

V

EN,ON

Hysteresis

Normal Operation mode

Sleep mode

t

EN

t

Data transmission

RxD

t

Data transmission

TxD

t

INH

t

MODE

RxD: „high“ or „low“

TxD: „high“ because

of internal pull-up

Standby mode:

Sleep mode:

t

MODE

The internal pull-up current source sets the TxD input to logical „high“ in case the TxD input is open.

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

in case the TxD input is open.