Data Sheet

11

Rev. 1.0

2016-08-05

TLE8457

LIN Transceiver with integrated Voltage Regulator

Functional Description

4.1.6

Mode Transition via EN pin

The EN input is used for operation mode control of the TLE8457. By setting the EN input logical “high” for the

triggered.

If the voltage level at the EN input is set logical “high” while the TLE8457 is in Sleep Mode, a transition to Init

Mode is initiated. If the EN input is continuously held “high” though powering up the voltage regulator and the

following reset pulse, Normal Operation Mode will be entered.

From Normal Operation Mode the TLE8457 can be set to either Sleep Mode or Standby Mode. If the EN input is

EN goes “low” (see Figure 7). It is recommended to program a short delay time from EN is set “low” until TxD

is set “low”, for preventing driving the bus dominant though mode transition to Sleep Mode.

The EN input has an integrated pull-down resistor to ensure the device remains in a low power mode if the EN

input is left open. The EN input has an integrated hysteresis (see Figure 7).

The TLE8457 changes the operation modes regardless of the signal on the BUS pin. In the case of a short circuit

failure between the LIN bus and GND, resulting in a permanent dominant signal, the TLE8457 can be set to

Sleep Mode.

Figure 7

Operation mode control

The EN input is blocked while the TLE8457 is in Init Mode and NRST is “low”, no mode transitions to Normal

Operation Mode is possible while a reset pulse is issued. After the NRST output goes “high”, mode control with

the EN input is released. At the same time the Initialization Watchdog timer starts (see “Initialization

Watchdog” on Page 15).

Note:

If the TLE8457 is being forced to Sleep Mode by the Initialization Watchdog while the EN input is

externally being held at a logical “high” level, the device will reinitiate Init Mode after the VCC

voltage has been discharged below ~1 V. In such applications additional supervision means are

recommended.

TLE8457_MODE_CONTROL

Normal Operation

mode

EN

Standby mode

Normal Operation

mode

Sleep mode

TxD

EN hysteresis

NRST

t

t

t

Normal Operation

mode

Init mode