33905 datasheet(53/91 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33904/5

LIN BLOCK

LIN INTERFACE DESCRIPTION

LIN BLOCK

LIN INTERFACE DESCRIPTION

The physical interface is dedicated to automotive LIN sub-

bus applications.

The interface has 20kbps and 10kbps baud rates, and

includes as well as a fast baud rate for test and programming

modes. It has excellent ESD robustness and immunity

against disturbance, and radiated emission performance. It

has safe behavior in case of a LIN bus short-to-ground, or a

LIN bus leakage during low power mode.

Digital inputs are related to device Vdd terminal.

POWER SUPPLY PIN (VSUP)

The VSUP-2 terminal is the supply pin for the LIN

interface. To avoid a false bus message, an under-voltage on

VSUP disables the transmission path (from TXD to LIN) when

VSUP falls below 6.1 V.

GROUND PIN (GND)

In case of a ground disconnection at the module level, the

LIN interface do not have significant current consumption on

the LIN bus pin when in the recessive state.

LIN BUS PIN (LIN1, LIN2)

The LIN terminal represents the single-wire bus

transmitter and receiver. It is suited for automotive bus

systems, and is compliant to the LIN bus specification 2.1 and

SAEJ2602-2.

The LIN interface is only active during Normal mode.

Driver Characteristics

The LIN driver is a low side MOSFET with internal over-

current thermal shutdown. An internal pull-up resistor with a

serial diode structure is integrated so no external pull-up

components are required for the application in a slave node.

An additional pull-up resistor of 1.0 k

Ω must be added when

the device is used in the master node. The 1.0 k

Ω pull resistor

can connected to LIN term or to ECU battery supply.

The LIN pin exhibits no reverse current from the LIN bus

line to VSUP, even in the event of a GND shift or VSUP

disconnection.

The transmitter has a 20 kbps, 10 kbps and fast baud rate,

which are selected by SPI.

Receiver Characteristics

The receiver thresholds are ratiometric with the device

Vsup2 voltage.

If the Vsup2 voltage goes below typ 6.1V, the LIN bus

enters into a recessive state even if communication is sent on

TXD.

If LIN driver temperature reached over temperature

threshold, the transceiver and receiver are disabled. When

the temperature falls below the over temperature threshold,

LIN driver and receiver will be automatically enabled.

DATA INPUT PIN (TXDL1, TXDL2)

The TXDl1 (TXDL2) input pin is the MCU interface to

control the state of the LIN output. When TXDL is LOW

(dominant), LIN output is LOW. When TXDL is HIGH

(recessive), the LIN output transistor is turned OFF.

This pin has an internal pull-up current source to Vdd to

force the recessive state if the input pin is left floating.

If the pin stays low (dominant sate) more than tTXDDOM, the

LIN transmitter goes automatically in recessive state. This is

reported by flag in LIN register.

DATA OUTPUT PIN (RXDL1, RXDL2)

The RXDl output pin is the MCU interface, which reports

the state of the LIN bus voltage.

LIN HIGH (recessive) is reported by a high voltage on

RXD, LIN LOW (dominant) is reported by a low voltage on

RXD.

LIN OPERATIONAL MODES

The LIN interface have two operational modes, Transmit

receiver and LIN disable modes.

TRANSMIT RECEIVE

In the TxRx mode, the LIN bus can transmit and receive

information.

When the 20kbps baud rate is selected, the slew rate and

timing are compatible with LIN protocol specification 2.1.

When the 10kbps baud rate is selected, the slew rate and

timing are compatible with J2602-2.

When the fast baud rate is selected, the slew rate and

timing are much faster than the above specification and allow

fast data transition.

SLEEP MODE

This mode is selected by SPI, and the transmission path is

disabled. Supply current for LIN block from VSUP2 is very low

(typ 3uA). LIN bus is monitor to detect wake-up event. In the

Sleep Mode, the internal 725 kOhm pull-up resistor is

connected and the 30 kOhm disconnected.

33905 Datasheet(PDF) 53 Page - Freescale Semiconductor, Inc

33905 Datasheet(HTML) 53 Page - Freescale Semiconductor, Inc

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