ATA6662 データシートの表示（PDF） - Atmel Corporation

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ATA6662

LIN Transceiver

Atmel Corporation 

ATA6662

3.13

Local Wake-up via Pin WAKE

A falling edge at pin WAKE, followed by a low level maintained for a certain time period (tWAKE),

results in a local wake-up request. The wake-up time (tWAKE) ensures that no transient, accord-

ing to ISO7637, creates a wake-up. The device switches to Fail-safe Mode. Pin INH is activated

(switches to VS) and the internal termination resistor is switched on. The local wake-up request

is indicated by a low level at pin RXD to interrupt the microcontroller and a strong pull-down at

pin TXD (see Figure on page 9). The voltage threshold for a wake-up signal is 3V below the VS

voltage with an output current of typical –3 µA. Even in the case of a continuous low at pin

WAKE it is possible to switch the IC into Sleep Mode via a low at pin EN. The IC will stay in

Sleep Mode for an unlimited time. To generate a new wake up at pin WAKE it needs first a high

signal > 6 µs before a negative edge starts the wake-up filtering time again.

Figure 3-3. Wake-up from Wake-up Switch

Wake pin

State change

INH

Low or floating

High

RXD

High or floating

Low

High

TXD

Voltage

regulator

EN

TXD weak pull-down resistor

Wake filtering time

tWAKE

Off state

Node in sleep state

TXD strong pull-down

Weak

pull-down

On state

Regulator wake-up time delay

Microcontroller start-up

delay time

Node in

operation

EN High

3.14

Wake-up Source Recognition

The device can distinguish between a local wake-up request (pin WAKE) and a remote wake-up

request (LIN bus). The wake-up source can be read on pin TXD in Fail-safe Mode. If an external

pull-up resistor (typically 5 kΩ) has been added on pin TXD to the power supply of the microcon-

troller, a high level indicates a remote wake-up request (weak pull-down at pin TXD) and a low

level indicates a local wake-up request (strong pull-down at pin TXD).

The wake-up request flag (signalled on pin RXD) as well as the wake-up source flag (signalled

on pin TXD) are reset immediately if the microcontroller sets pin EN to high (see Figure 3-2 on

page 6 and Figure 3-3 on page 7).

7

4916O–AUTO–05/10

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