33389 datasheet(22/49 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33389

FUNCTIONAL DEVICE OPERATION

OPERATIONAL MODES

CAN Transceiver Modes

The CAN transceiver has its own functioning modes:

RXTX mode, Term VBAT/Term VCC mode, and RX Only

mode. They are controlled by the Transceiver Control/Status

• RXTX mode—Full transmitting and receiving capabilities

are enabled. Full failure detection is enabled.

Note: Standard/RXTX and Extended/RXTX are

equivalent.

• RX Only mode—The transmitter is disabled but the

receive portion of the transceiver remains active. In this

mode, RX reports bus and TX activity (RX = TX or Bus

dominant).

Note: Standard/RX Only and Extended/RX Only are

equivalent.

• Bus Stand-by mode—Is the Low Power mode for the CAN

transceiver. The driver and receivers are disabled. Wake-

up capability on both bus lines as well as Failure 3, 4, 7,

and 8 detection are enabled. RTL termination is set to

VBAT in the Bus Stand-by mode.

Low Power Modes

The transceiver provides a Low Power mode, entered and

exited by a SPI command. This is the Bus Stand-by mode

having the lowest power consumption for the transceiver.

CANL is biased to the battery voltage via the RTL output and

the pull-up current source on CANL and pull down current

source on CANH are disabled. Wake-up requests are

recognized by the transceiver when a dominant state is

detected on either bus wake-up lines. On a Bus wake-up

request, the SBC will activate the INT output or, if it is in the

Sleep mode, switch to the Normal Request mode. This event

is stored in the Wake-Up Input Status Register (WUISR).

To prevent a false wake-up resulting from transients or

(RF) fields, wake-up threshold levels have to be maintained

for a certain time. While in the Transceiver Low Power mode,

failure detection circuit remains partly active preventing

increased power consumption in cases of error 3, 4, 7, and 8.

Power-On

After the VBAT supply is switched ON, the SBC is in

Normal Request mode. Bus Stand-by is the corresponding

mode for the CAN transceiver.

The CAN transceiver is supplied by V2. As long as V2 is

below its under voltage threshold, the transceiver is forced to

Bus Stand-by mode (fail safe property).

SBC MODES

Global Power Save Concept

The SBC minimizes power consumption of the ECU.

Several operating modes are available to go to low power

consumption when the full activity is not required. Several

possibilities are provided to wake-up the ECU. This permits

peripherals or the microcontroller to be switched OFF when

no activity on the ECU is required.

Two switchable independent supply voltages (V1 and V2)

are provided for optimum ECU power management.

Generalities

The SBC can be operated in four modes:

1. Sleep

2. Stand-by

3. Normal

4. Emergency

After reset, the 33389 is automatically initialized to the

temporary mode, Normal Request, while waiting for

microcontroller configuration.

Reset Mode

This mode is entered after SBC power-up, or if an incorrect

software watchdog trigger occurs. The minimum duration for

reset mode is 1.0 ms typical, and unless there is a V1 failure

condition, the SBC enters the Normal Request mode after

reset.

In the case of a V1 failure condition leading to V1 low (ex:

short to ground), the SBC switches to the Reset mode. If V1

is still below the reset threshold after 100 ms, the behavior

depends upon the device version A or C:

• C version: The 33389CDW and the 33389CDH will remain

in the reset mode.

• D version: The 33389DDW and the 33389DEG will remain

in the reset mode. Note that the reset mode threshold for

the D version is slightly higher than the C version.

Normal Request Mode

The Normal Request mode is the Default mode after

33389 reset. V1 is active, while V2 and V3 are passive. The

SBC is not configured. The default values are set in the

registers. The SBC awaits data configuration via the SPI.

If no SPI data is received 75 ms after the Reset is

released, the SBC switches itself into the Sleep mode.

The software timing word (in SWCR) provides the data the

SBC must receive to consider when the microcontroller

begins the configuration sequence. Once received, this

software timing word, and the watchdog timer, become

active. Any other control data can then be sent from the

microcontroller to SBC.

The watchdog is not active in the Normal Request mode

before the software timing word is programmed into the SBC.

In this mode, neither V2 nor the CAN transmitter are active.

33389 Datasheet(PDF) 22 Page - Freescale Semiconductor, Inc

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