33912 datasheet(33/47 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33912

FUNCTIONAL DEVICE OPERATIONS

OPERATIONAL MODES

Current Limit (LIN Interrupt)

The output low side FET is protected against over-current

conditions. In case of an over-current condition (e.g. LIN bus

short to VBAT), the transmitter will not be shut down. The bit

LINOC in the LIN Status Register (LINSR) is set.

If the LINM bit is set in the Interrupt Mask Register (IMR),

an Interrupt IRQ will be generated.

Over-temperature Shutdown (LIN Interrupt)

The output low side FET is protected against over-

temperature conditions. In case of an over-temperature

condition, the transmitter will be shut down and the LINOT bit

in the LIN Status Register (LINSR) is set.

If the LINM bit is set in the Interrupt Mask Register (IMR),

an Interrupt IRQ will be generated.

The transmitter is automatically re-enabled once the

condition is gone and TXD is high.

A read of the LIN Status Register (LINSR) with the TXD pin

high, will re-enable the transmitter.

RXD Short-circuit Detection (LIN Interrupt)

The LIN transceiver has a short-circuit detection for the

RXD output pin. In case of an short-circuit condition, either 5V

or Ground, the RXSHORT bit in the LIN Status Register

(LINSR) is set and the transmitter is shut down.

If the LINM bit is set in the Interrupt Mask Register (IMR),

an Interrupt IRQ will be generated.

The transmitter is automatically re-enabled once the

condition is gone (transition on RXD) and TXD is high.

A read of the LIN Status Register (LINSR) without the RXD

pin short-circuit condition will clear the bit RXSHORT.

TXD Dominant Detection (LIN Interrupt)

The LIN transceiver monitors the TXD input pin to detect a

stuck in dominant (0V) condition. In case of a stuck condition

(TXD pin 0V for more than 1 second (typ.)), the transmitter is

shut down and the TXDOM bit in the LIN Status Register

(LINSR) is set.

If the LINM bit is set in the IMR, an Interrupt IRQ will be

generated.

The transmitter is automatically re-enabled once TXD is

high.

A read of the LIN Status Register (LINSR) with the TXD pin

at 5V will clear the bit TXDOM.

LIN Dominant Voltage Level Selection

The LIN dominant voltage level can be selected by the bit

LDVS in the LIN Control Register (LINCR).

LIN Receiver Operation Only

While in Normal Mode, the activation of the RXONLY bit

disables the LIN TXD driver. If case of a LIN error condition,

this bit is automatically set. If a low-power mode is selected

with this bit set, the LIN wake-up functionality is disabled,

then in STOP Mode, the RXD pin will reflect the state of the

LIN bus.

STOP Mode And Wake-up Feature

During Stop Mode operation, the transmitter of the

physical layer is disabled. If the LIN-PU bit was set in the Stop

Mode sequence, the internal pull-up resistor is disconnected

from VSUP and a small current source keeps the LIN pin in

the recessive state. The receiver is still active and able to

detect wake-up events on the LIN bus line.

A dominant level longer than TPROPWL followed by a rising

edge will generate a wake-up interrupt, and will be reported

in the Interrupt Source Register (ISR). Also see Figure 11,

page 19.

SLEEP Mode And Wake-up Feature

During Sleep Mode operation, the transmitter of the

physical layer is disabled. If the LIN-PU bit was set in the

Sleep Mode sequence, the internal pull-up resistor is

disconnected from VSUP and a small current source keeps

the LIN pin in recessive state. The receiver must be active to

detect wake-up events on the LIN bus line.

A dominant level longer than TPROPWL followed by a rising

edge will generate a system wake-up (Reset), and will be

reported in the Interrupt Source Register (ISR). Also see

Figure 10, page 19.

33912 Datasheet(PDF) 33 Page - Freescale Semiconductor, Inc

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