33742 datasheet(36/65 Pages) FREESCALE

36 / 65 page

Analog Integrated Circuit Device Data

Freescale Semiconductor

33742

FUNCTIONAL DEVICE OPERATION

OPERATIONAL MODES

Figure 21. CAN Signals in TXRX and Sleep Modes

CAN IN SLEEP MODE WITH WAKE-UP ENABLE

When the CAN interface is in Sleep mode with wake-up

enable, the CAN bus traffic is detected. The CAN bus wake-

up is a pattern wake-up.

PATTERN WAKE-UP

In order to wake up the CAN interface, the following criteria

must be fulfilled:

• The CAN interface wake-up receiver must receive a series

of three consecutive valid dominant pulses, each of which

must be longer than 500 ns and shorter than 500

µs.

• The distance between 2 pulses must be lower than 500

µs.

• The three pulses must occur within a time frame of 1.0 ms.

The pattern wake-up of the 33742 CAN interface allow

wake-up by any CAN message content.

Figure 22 below illustrates the CAN signals during a CAN

bus Sleep state and wake-up sequence.

Figure 22. CAN Bus Signal During Can Sleep State and Wake-Up Sequence

CANL

CANH

TXD

RXD

Ground

2.5 V

CANL Dominant

CANH Dominant

CANL/CANH Recessive

CAN in TXRX Mode

CAN in Sleep Mode

(Wake-Up Enable or Disable)

CAN in TXRX Mode

(Controlled by SPI Command)

CANL

CANH

TXD

RXD

Ground

2.5 V

CANL Dominant

CANH Dominant

CANL/CANH Recessive

CAN in TXRX Mode

CAN in Sleep Mode (Wake-Up Enable)

Incoming CAN Message

CANL Dominant

CANH Dominant

CANL Dominant

CANH Dominant

CANL Dominant

CANH Dominant

WU Receiver

Internal Wake-Up Signal

Min 500 ns

Max 500

µs

CAN Bus Sleep State

Pulse # 1

Pulse # 2

Pulse # 3

33742 Datasheet(PDF) 36 Page - Freescale Semiconductor, Inc

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