ATA6662 Ver la hoja de datos (PDF) - Atmel Corporation

Número de pieza

componentes Descripción

Fabricante

ATA6662

LIN Transceiver

Atmel Corporation 

ATA6662

3. Functional Description

3.1 Physical Layer Compatibility

Since the LIN physical layer is independent from higher LIN layers (e.g., the LIN protocol layer),

all nodes with a LIN physical layer according to revision 2.x can be mixed with LIN physical layer

nodes, which, according to older versions (i.e., LIN 1.0, LIN 1.1, LIN 1.2, LIN 1.3), are without

any restrictions.

3.2 Supply Pin (VS)

Undervoltage detection is implemented to disable transmission if VS falls to a value below 5V in

order to avoid false bus messages. After switching on VS, the IC switches to Fail-safe Mode and

INHIBIT is switched on. The supply current in Sleep Mode is typically 10 µA.

3.3 Ground Pin (GND)

The ATA6662 does not affect the LIN Bus in the case of a GND disconnection. It is able to han-

dle a ground shift up to 11.5% of VS.

3.4 Bus Pin (LIN)

A low-side driver with internal current limitation and thermal shutdown and an internal pull-up

resistor are implemented as specified for LIN 2.x. The voltage range is from –27V to +40V. This

pin exhibits no reverse current from the LIN bus to VS, even in the case of a GND shift or VBatt

disconnection. The LIN receiver thresholds are compatible to the LIN protocol specification.The

fall time (from recessive to dominant) and the rise time (from dominant to recessive) are slope

controlled. The output has a self-adapting short circuit limitation; that is, during current limitation,

as the chip temperature increases, the current is reduced.

3.5 Input/Output Pin (TXD)

In Normal Mode the TXD pin is the microcontroller interface to control the state of the Lin output.

TXD must be at Low- level in order to have a low LIN Bus. If TXD is high, the LIN output

transistor is turned off and the Bus is in recessive state. The TXD pin is compatible to both a

3.3V or 5V supply. During fail-safe Mode, this pin is used as output and is signalling the wake-up

source (see Section 3.14 “Wake-up Source Recognition” on page 7). It is current limited to

< 8 mA.

3.6 TXD Dominant Time-out Function

The TXD input has an internal pull-down resistor. An internal timer prevents the bus line from

being driven permanently in dominant state. If TXD is forced to low longer than tDOM > 6 ms, the

pin LIN will be switched off (Recessive Mode). To reset this mode, switch TXD to high (> 10 µs)

before switching LIN to dominant again.

3.7 Output Pin (RXD)

This pin reports to the microcontroller the state of the LIN bus. LIN high (recessive) is reported

by a high level at RXD, LIN low (dominant) is reported by a low voltage at RXD. The output is an

open drain, therefore, it is compatible to a 3.3V or 5V power supply. The AC characteristics are

defined with a pull-up resistor of 5 kΩ to 5V and a load capacitor of 20 pF. The output is short-

protected. In Unpowered Mode (VS = 0V), RXD is switched off. For ESD protection a Zener

diode is integrated, with VZ = 6.1V.

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4916O–AUTO–05/10

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