Analog Integrated Circuit Device Data



Freescale Semiconductor

27

33663

FUNCTIONAL DESCRIPTION

FUNCTIONAL PIN DESCRIPTION

ENABLE INPUT PINS (EN1, EN2)

EN1 (EN2) input pin controls the operation mode of the interface. If EN1 (EN2) = 1, the interface is in Normal mode, TXD1

during this delay. (see Figure 22). Both LIN Modules enter Sleep Mode if EN1 & EN2 LOW.

A combination of the logic levels on EN1 (EN2) and TXD1 (TXD2) pins allows the device to enter in Fast Baud Rate mode of

operation (see Figure 19).

INHIBIT OUTPUT PINS (INH1, INH2)

The INH1 (INH2) output pin is connected to an internal high side power MOSFET. The pin has two possible main functions. It

can be used to control an external switchable voltage regulator having an inhibit input. It can also be used to drive the LIN bus

external resistor in the master node application, thanks to its high drive capability. This is illustrated in Figure 26.

In Sleep mode, INH1 (INH2) is turned OFF. If a voltage regulator inhibit input is connected to INH1 (INH2), the regulator will

be disabled. If the master node pull-up resistor is connected to INH1 (INH2), the pull-up resistor will be unpowered and left

floating.

In case of a INH1 (INH2) thermal shutdown, the high side is turned off and the LIN1 (LIN2) transmitter and receiver are in

recessive state. An external 10 to 100 pF capacitor on INH1 (INH2) pin is advised in order to improve EMC performances.

WAKE INPUT PINS (WAKE1, WAKE2)

The WAKE1 (WAKE2) pin is a high-voltage input used to wake-up the device from the Sleep mode. WAKE1 (WAKE2) is

usually connected to an external switch in the application.

The WAKE1 (WAKE2) pin has a special design structure and allows wake-up from both HIGH to LOW or LOW to HIGH

transitions. When entering into Sleep mode, the corresponded LIN Module monitors the state of its WAKE pin and stores it as a

reference state. The opposite state of this reference state will be the wake-up event used by the LIN Module to enter again into

Normal mode.

An internal filter is implemented to avoid false wake-up event due to parasitic pulses (See Figure 16). WAKE1 (WAKE2) pin

input structure exhibits a high-impedance, with extremely low input current when voltage at this pin is below 27 V. Two serial

resistors should be inserted in order to limit the input current mainly during transient pulses and ESD. The total recommended

resistor value is 33 k

. An external 10 to 100 nF capacitor is advised for better EMC and ESD performances.

Important The WAKE1 (WAKE2) pin should not be left open. If the wake-up function is not used, WAKE1 (WAKE2) should

be connected to ground to avoid a false wake-up.