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

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ZMD30011

LIN Transceiver

Datasheet

PRELIMINARY

2.5

TXD-Pin

This CMOS-input connects the external protocol controller to the transceiver. A TXD-low-level is transmitted as a

LIN-low-level too. The LIN-driver is tristated if TXD is high, hence the bus is set to recessive state using the pull-up-

resistor.

The TXD-input is equipped with an internal pull-down resistor and an internal timer preventing the LIN-bus from

being permanently driven in the dominant state.

2.6

GND-Pin

The GND-pin represents the ground level. Level suspensions ≤ 2 V do not influence the data transfer. A ground loss

in the recessive state does not lead to a significant current at the LIN-pin.

2.7

LIN-Bus-Pin

The circuit blocks receiver and transmitter realize the bi-directional LIN-bus-connection.

Receiver:

The input voltage of the receiver depends on the supply voltage ratiometricly. The threshold amounts to 0.4

respective 0.6 VSUP with a typical hysteresis of 10 % VSUP. The receiver is active in the sleep mode too. The filter

in the input signal path suppresses spikes with a duration of < 4 s.

Transmitter:

The transmitter consists of a low-side-driver supplying 20 mA at a typical output-voltage of 1 V.

It transmits a low level if there is a low level on the TXD-pin. An internal pull-up resistor of 30 k

pushes the bus

node to the high level in the locked transmitter state.

A diode is located in series to the resistor and prevents a reflow current from the bus into the battery supply line in

the case of a local supply loss or a ground level shift.

The transmitter is only active in the normal-mode. In the sleep-mode and in the wait-mode the transmitter is

tristated. A slope-control adjusts both edges (falling edge from the recessive to the dominant driver state and rising

edge from the dominant to the recessive driver state) to 2V/µs typically. As a result the electromagnetic emission is

minimal.

The capacitive LIN-bus-load has to be restricted to a total of <=10 nF at a total resistance 0.5 k

in order to ensure

the symmetry of both edges.

In the case of short circuits to battery supply the drivers current limitation begins to work at 180 mA typical. The

driver is also protected against thermal overloads.

In the range from -18 V to 30 V the current VSUP-LIN is determined only by the pull-up-resistor. A VSUP loss in the

recessive driver state does not lead to a significant current at the LIN-pin.

2.8

VSUP-Pin

The VSUP-pin has to be protected by an external diode against reverse polarity of the battery supply.

The protection against galvanic and capacitive coupled transients is realized by a special internal circuitry.

The operational supply voltage reaches from 6.5 to 18 V DC. A voltage control prevents an incorrect bus transfer

below the operating voltage range.

The quiescent current in the sleep-mode amounts to typical 14 A. In the normal-mode the quiescent current

amounts to max. 2 mA in the state of dominant LIN-bus.