Copyright © 2006, ZMD AG, Rev. 0.8, 2006-04-12

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ZMD30011

LIN Transceiver

Datasheet

PRELIMINARY

3. Functional Description

3.1

Sequence Control

The internal sequence control manages the operation modi and their transient states (see figure 2).

normal-mode:

INH=high, EN=high, bus transfer permitted

sleep-mode:

INH tristated, EN=low, only bus reception possible

The receiver stands in the active state and the driver is tristated. Setting EN to high brings

the transceiver into the normal-mode. Applying Wake=high at the WAKE pin or a LIN bus

wake-up message bring the device into the wait-mode.

wait-mode:

INH=high, EN=low, bus transfer impossible,

Switching EN to high switches the transceiver into the normal-mode from another mode.

The transceiver changes into the wait-mode too from another mode if the junction temperature rises over 150°C.

The change from wait-mode into the normal mode is caused by setting EN to high.

3.2

Wake-Up-Events

There are three methods how to wake up the transceiver from sleep-mode:

(1) Wake-up by WAKE-pin active

An internal timer supervises the level at the WAKE-pin. If the WAKE-level falls from WAKE-high to WAKE-low and

stays there for minimal 40µs than the timer activates the INH-output. The transceiver switches into the wait-mode

within maximal 150 µs after the falling edge of the WAKE pin. By doing so spike pulses are filtered out effectively.

When the external regulator has reached its output level and the system is ready than the protocol-controller

switches EN=high. The transceiver changes into to the normal-mode and gets ready for bus transfers.

(2) Wake-up by bus-message:

The reception of a LIN-low-level (dominant state for 250 s to 5ms) in the sleep-mode triggers the following wake-

up-sequence:

At the latest 150 s after the falling edge of the LIN signal the transceiver activates the system’s voltage regulator by

setting INH=high and goes to the wait-mode. After a system reaction time (until regulator and application active) the

protocol-controller sets EN=high. The device switches to the normal-mode and gets ready for bus transfers. An anti-

bounce filter suppresses spike pulses from the LIN bus.

(3) Wake-up by EN-pin active:

There are systems with an external power supply which are also active in the LIN-transceiver’s sleep-mode. If the

application of such a system gets active then the protocol controller sets EN=high. The transceiver switches to

normal-mode at once and is ready for the transfer of a wake-up-frame from the protocol controller to the LIN-bus. In

such applications the INH-pin can be used for other purposes, e.g. for an interrupt request.