908E624_12 Datasheet, PDF (23/39 Pages) Freescale Semiconductor, Inc – Integrated Triple High Side Switch Embedded MCU and Lin Serial Communication for Relay Drivers

FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
The LIN pin offers high susceptibility immunity level from
external disturbance, guaranteeing communication during
external disturbance.
The LIN transmitter circuitry is enabled in Normal and
Normal Request mode.
An over-current condition (e.g. LIN bus short to V_BAT) or a
over-temperature in the output low side FET will shutdown
the transmitter and set the LINFAIL flag in the SPI Status
Register.
For improved performance and safe behavior in case of
LIN bus short to Ground or LIN bus leakage during low power
mode the internal pull-up resistor on the LIN pin can be
disconnected, with the LIN-PU bit in the SPI Control Register,
and a small current source keeps the LIN bus at recessive
level. In case of a LIN bus short to GND, this feature will
reduce the current consumption in STOP and SLEEP modes.
MODE2:1 LINSL2:1
LIN-PU
VSUP1
LINWU
LINFAIL
Control
2µA
TXD
Slope
Control
Wake-up
Filter
30k
LIN bus
GND
RXD
Figure 15. LIN Interface
TXD Pin
The TXD pin is the MCU interface to control the state of the
LIN transmitter (see Figure 2, page 2). When TXD is LOW,
the LIN pin is low (dominant state). When TXD is HIGH, the
LIN output MOSFET is turned off (recessive state). The TXD
pin has an internal pull-up current source in order to set the
LIN bus to recessive state in the event, for instance, the
microcontroller could not control it during system power-up or
power-down.
RXD Pin
The RXD transceiver pin is the MCU interface, which
reports the state of the LIN bus voltage. LIN HIGH (recessive
state) is reported by a high level on RXD, LIN LOW (dominant
state) by a low level on RXD.
STOP Mode and Wake-up Feature
During STOP mode operation the transmitter of the
physical layer is disabled. In case the bit LIN-PU 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 recessive state. The receiver is still active and
able to detect wake-up events on the LIN bus line.
A dominant level longer than t_PROPWL followed by an rising
edge will generate a wake-up interrupt and set the LINWF
flag in the SPI Status Register. Also see Figure 9, page 15.
SLEEP Mode and Wake-up Feature
During SLEEP mode operation the transmitter of the
physical layer is disabled. In case the bit LIN-PU was set in
the Sleep mode sequence the internal pull-up resistor is
Analog Integrated Circuit Device Data
Freescale Semiconductor
908E624
23