33389 datasheet(19/49 Pages) FREESCALE

19 / 49 page

Analog Integrated Circuit Device Data

Freescale Semiconductor

33389

FUNCTIONAL DEVICE OPERATION

Supply and VBAT Block

• VBAT Monitoring—VBAT is the main power supply coming

from the battery voltage after an external protection diode

(for reverse battery). VBAT is monitored for under voltage

and over voltage.

• VBAT Under Voltage—VBAT is monitored for under voltage

if it is below 4.0 V the BatFail flag is set in the VSSR

microcontroller.

• VBAT Over Voltage— When VBAT is > 20 V, the BatHigh

flag is set in the VSSR register. A maskable interrupt is

sent to the microcontroller. No specific action is taken to

reduce current consumption (to limit power dissipation).

This is to allow the entire flexibility to the microcontroller for

a decision.

CAN Transceiver

The device incorporates a low speed 125 kBaud CAN

physical interface. Its electrical parameters for the CANL,

CANH, RTL,RTH, RX, and TX pins are identical to the 33388,

stand alone CAN physical interface.

The mode control for the CAN transceiver (Normal, VBAT

Stand-by, Sleep, etc.) are selectable through the 33389 SPI

interface.

• Baud Rate up to 125 kBit/s

• Supports unshielded bus wires

• Short-circuit proof to battery and ground in 12 V powered

systems

• Supports single-wire transmission modes with ground

offset voltages up to 1.5 V

• Automatic switching to single wire mode in case of bus

failures

• Automatic reset to differential mode if bus failure is

removed

• Low Electromagnetic Interference (EMI) due to built-in

slope control and signal symmetry

• Fully integrated receiver filters

• Thermally protected

• Bus lines protected against automotive transients

• Low current Bus Stand-by mode with wake-up capability

via the bus

• An unpowered node does not disturb the bus lines

Figure 5. CAN Simplified Block Diagram

CONSEQUENCE OF FAILURE DETECTIONS

S1 is the switch from RTH to Ground

S2 is the switch from RTL to V2 and

S3 is the switch from RTL to VBAT

Each failure type provides data concerning which switch is

open and which driver is disabled.

Failure 1: Nothing done

Failure 2: Nothing done

Failure3: S1 open. Driver CANH is disabled

Failure4: S2 and S3 open. Driver CANL is disabled

Failure5: Nothing done

Failure6: S2 and S3 open. Driver CANL disabled

Failure7: S2 and S3 open. Driver CANL disabled

Failure8: S1 Open. CANH driver disable

CAN Transceiver Description

The CAN transceiver is an interface between CAN

protocol controller and the physical bus. It is intended for low

—

In Sleep Mode, During

Disable Time of Cyclic

Sense if Configured

—

Over Temp Threshold Reached

—

V1 Disabled (for any reason)

—

V2 Over Temperature Shutdown

Table 8. V3 Control

Termination

Protection

CAN_H

CAN_L

RTH

RTL

VDD2

SPI

Transmitter

Receiver

- Fail Detect

- Receive Mode

VDD2 VBAT

CAN Transceiver Register

Drivers

CAN transceiver simplified block diagram

12.5k

VDD BAT

RTL

CANH

CANL

RTH

33389 Datasheet(PDF) 19 Page - Freescale Semiconductor, Inc

33389 Datasheet(HTML) 19 Page - Freescale Semiconductor, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49

Datasheet Download

Link URL