ATA6560 datasheet(6/28 Pages) MICROCHIP

6 / 28 page

ATA6560/1

DS20005991A-page 6

 2018 Microchip Technology Inc.

1.1.2

SILENT MODE (ONLY FOR THE

ATA6560)

A low level on the NSIL pin (available on pin 5) and on

the STBY pin selects the Silent mode. This

receive-only mode can be used to test the connection

of the bus medium. In the Silent mode, the ATA6560

can still receive data from the bus, but the transmitter is

disabled and therefore no data can be sent to the CAN

bus. The bus pins are released to recessive state. All

other IC functions, including the HSC, continue to oper-

ate as they do in the Normal mode. The Silent mode

can be used to prevent a faulty CAN controller from

disrupting all network communications.

1.1.3

STANDBY MODE

A high level on the STBY pin selects the Standby

mode. In this mode, the transceiver cannot transmit or

correctly receive data via the bus lines. The transmitter

and the HSC are switched off to reduce current con-

sumption, and only the low-power Wake-Up Compara-

tor (WUC) monitors the bus lines for a valid wake-up

signal. A signal change on the bus from “Recessive” to

“Dominant,” followed by a dominant state longer than

twake, switches the RXD pin to low to signal a wake-up

request to the microcontroller.

In the Standby mode, the bus lines are biased to

ground to reduce current consumption to a minimum.

The WUC monitors the bus lines for a valid wake-up

signal. When the RXD pin switches to low to signal a

wake-up request, a transition to the Normal mode is not

triggered until the microcontroller forces back the STBY

pin to low. A bus dominant time-out timer prevents the

device from generating a permanent wake-up request

by switching the RXD pin to high.

For ATA6560 only: If the NSIL input pin is set to low in

the Standby mode, the internal pull-up resistor causes

an additional quiescent current from VIO to GND.

Microchip recommends setting the NSIL pin to high in

the Standby mode.

1.2

Fail-Safe Features

1.2.1

TXD DOMINANT TIME-OUT

FUNCTION

A TXD dominant time-out timer is started when the

TXD pin is set to low. If the low state on the TXD pin

persists for longer than tto(dom)TXD, the transmitter is

disabled, releasing the bus lines to a recessive state.

This function prevents a hardware failure, software

application failure, or both from driving the bus lines to

a permanent dominant state (blocking all network

communications). The TXD dominant time-out timer is

reset when the TXD pin is set to high (≥ 4 µs).

1.2.2

INTERNAL PULL-UP STRUCTURE

AT TXD, NSIL, AND STBY INPUT

PINS

The TXD, STBY, and NSIL pins have an internal pull-up

to VIO. This ensures a safe, defined state in case one

or all of these pins are left floating. Pull-up currents flow

in these pins in all states, meaning all pins should be in

a high state during the Standby mode to minimize the

current consumption.

1.2.3

UNDERVOLTAGE DETECTION ON

PINS VCC AND VIO

If VVCC or VVIO drops below their respective undervoltage

detection levels (Vuvd(VCC) and Vuvd(VIO), see Section 2.0

“Electrical Characteristics”), the transceiver switches

off and disengages from the bus until VVCC and VVIO have

recovered. The low-power WUC is only switched off

during a VCC or VIO undervoltage. The logic state of the

STBY pin is ignored until the VCC voltage or the VIO

voltage has recovered.

1.2.4

BUS WAKE-UP TIME-OUT

FUNCTION

In the Standby mode, a bus wake-up time-out timer is

started when the CAN bus changes from recessive to

dominant state. If the dominant state on the bus persists

for longer than tto_bus, the RXD pin is switched to high.

This function prevents a clamped dominant bus (due to a

bus short circuit or a failure in one of the other nodes on

the network) from generating a permanent wake-up

request. The bus wake-up time-out timer is reset when

the CAN bus changes from dominant to recessive state.

1.2.5

OVERTEMPERATURE PROTECTION

The output drivers are protected against overtemperature

conditions. If the junction temperature exceeds the

shutdown junction temperature, TJsd, the output drivers

are disabled until the junction temperature drops below

TJsd and pin TXD is at a high level again. The TXD

condition ensures that output driver oscillations due to

temperature drift are avoided.

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