Chapter 23 LIN Physical Layer (S12LINPHYV2)
S12ZVHY/S12ZVHL Family Reference Manual Rev. 1.05
754
Freescale Semiconductor
•
Compliant with the SAE J2602-2 LIN standard.
•
Standby mode with glitch-filtered wake-up.
•
Slew rate selection optimized for the baud rates: 10.4 kbit/s, 20 kbit/s and Fast Mode (up to
250 kbit/s).
•
Switchable 34 k
/330 k
pullup resistors (in shutdown mode, 330 k
only
•
Current limitation for LIN Bus pin falling edge.
•
Overcurrent protection.
•
LIN TxD-dominant timeout feature monitoring the LPTxD signal.
•
Automatic transmitter shutdown in case of an overcurrent or TxD-dominant timeout.
•
Fulfills the OEM “Hardware Requirements for LIN (CAN and FlexRay) Interfaces in Automotive
Applications” v1.3.
The LIN transmitter is a low-side MOSFET with current limitation and overcurrent transmitter shutdown.
A selectable internal pullup resistor with a serial diode structure is integrated, so no external pullup
components are required for the application in a slave node. To be used as a master node, an external
resistor of 1 k
must be placed in parallel between VLINSUP and the LIN Bus pin, with a diode between
VLINSUP and the resistor. The fall time from recessive to dominant and the rise time from dominant to
recessive is selectable and controlled to guarantee communication quality and reduce EMC emissions. The
symmetry between both slopes is guaranteed.
23.1.2
Modes of Operation
The LIN Physical Layer can operate in the following four modes:
1. Shutdown Mode
The LIN Physical Layer is fully disabled. No wake-up functionality is available. The internal
pullup resistor is replaced by a high ohmic one (330 k
) to maintain the LIN Bus pin in the
recessive state. All registers are accessible.
2. Normal Mode
The full functionality is available. Both receiver and transmitter are enabled.
3. Receive Only Mode
The transmitter is disabled and the receiver is running in full performance mode.
4. Standby Mode
The transmitter of the LIN Physical Layer is disabled. If the wake-up feature is enabled, the internal
pullup resistor can be selected (330 k
or 34 k
). The receiver enters a low power mode and
optionally it can pass wake-up events to the Serial Communication Interface (SCI). If the wake-up
feature is enabled and if the LIN Bus pin is driven with a dominant level longer than t
WUFR
followed by a rising edge, the LIN Physical Layer sends a wake-up pulse to the SCI, which requests
a wake-up interrupt. (This feature is only available if the LIN Physical Layer is routed to the SCI).
