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AS8650

Datasheet - Detailed Descr i p ti on

7.12 CAN Transceiver

The AS8650 provides an advanced interface between the protocol controller and the physical bus in a Controller Area Network (CAN) node. This

is intended for automotive high-speed CAN application (up to 1 Mbit/s), providing differential transmit capability to the bus and differential receive

capability to the CAN controller. It is fully compatible to the ISO 11898 standard and offers excellent Electromagnetic Compatibility (EMC)

performance. The CAN is a high speed, low complexity protocol with improved EMI and EMC performance. The CAN is a serial communication

protocol efficiently supporting the control of mechatronic nodes in a distributive automotive application. The basic blocks of the CAN Transceiver

are described below:

7.12.1 BUS Driver

This driver has the basic functionality of relaying the data from the microcontroller on to the CAN bus. The data on the CAN needs to have a

controlled slew to reduced EMI. A low side driver is used which has an inherent reverse polarity protection. It has a Short-Circuit current

limitation.

7.12.2 Normal Receiver

It relays the data from the CAN bus to the microcontroller in Normal mode.

7.12.3 Low Power Receiver

It relays the data from the CAN bus to the microcontroller in low power mode state.

7.12.4 Operating Modes

The CAN Transceiver provides the following operating modes:

NORMAL: Non low power mode

RECEIVE ONLY: Non low power mode

STANDBY: Low power mode

SLEEP: Low power mode

detector is active. The power consumption is significantly reduced respect the non low power operation modes. The WAKE_REMOTE reflects

the remote wake up detector output; WAKE_LOCAL reflects the input signal on WAKE pin.

7.12.5 Local Wake-up Event

WAKE_LOCAL rises up. At the same time the biasing of the pin is switched to pull-up. In current application wake pin is initially pulled-down to

ground using external resistor on power up. For valid wake-up, the WAKE pin needs a rising edge.

Table 14. Operating Modes

State

TxD

Transmitter

Normal

Receiver

Low Power Receiver

Bust State

NORMAL

L

Enabled

Enabled

Disabled

Dominant

H

Enabled

Enabled

Disabled

Recessive

REC ONLY

X

Disabled

Enabled

Disabled

(CANH, CANL are not driven)

STANDBY

X

Disabled

Disabled

Enabled

(CANH, CANL are not driven)

SLEEP

X

Disabled

Disabled

Enabled

(CANH, CANL are not driven)