33742 datasheet(35/65 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33742

FUNCTIONAL DEVICE OPERATION

OPERATIONAL MODES

CAN SLEEP MODE

The 33742 offers two CAN Sleep modes:

• Sleep mode with CAN wake-up enable: detection of

incoming CAN message and SBC wake-up.

• Sleep mode with CAN wake-up disable: no detection of

incoming CAN message.

The CAN Sleep modes are set via the CAN SPI register.

In CAN Sleep mode (with wake-up enable or disable), the

CAN interface is internally supplied from the VSUP pin. The

voltage at V2 pin can be either 5.0 V or turned off. When the

CAN is in Sleep mode, the current sourced from V2 is

extremely low. In most cases the V2 voltage is off; however,

the CAN can be placed into Sleep mode even with 5.0 V

applied on V2.

In CAN Sleep mode, the CANH and CANL drivers are

disabled, and the receiver is also disabled. CANH and CANL

are high-impedance mode to ground.

CAN SIGNALS IN TXRX AND SLEEP MODES

When the CAN interface is set back into TXRX mode by an

SPI command, CAN H and CANL are set in recessive level.

This is illustrated in Figure 21.

Table 10. CAN Interface/33742 Modes and Pin Status—Operation without Ballast on V2 (45)

Mode

CAN Mode

(Controlled by SPI)

V2 Voltage

TXD Pin

RXD Pin

CANH/CANL

(Disconnected from

Other Node)

CAN

Communication

Unpowered

–

0.0 V

LOW

Floating to GND

Reset (with Ballast)

–

0.0 V

LOW

Floating to GND

Normal Request

without Ballast.

V2 Connected to

VDD

–

5.0 V

LOW

5.0 V

Floating to GND

Standby without

External Ballast,.

V2 connected to VDD

Normal or Sleep

5.0 V

0.0 V

5.0 V

Floating to GND

Normal without

External Ballast.

V2 Connected to

VDD

Normal

Slew Rate 0, 1, 2,3

5.0 V

Bus Recessive

CANH = CANL = 2.5 V

YES

Normal without

External Ballast,.

V2 Connected to

VDD

Sleep

5.0 V

0.0 V

5.0 V

Floating to GND

Sleep

0.0 V

LOW

Floating to GND

NO.

Wake-up if enabled

Stop

Sleep

0.0 V

LOW

Floating to GND

NO.

Wake-up if enabled

Notes

45.

33742 Datasheet(PDF) 35 Page - Freescale Semiconductor, Inc

33742 Datasheet(HTML) 35 Page - Freescale Semiconductor, Inc

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