Datasheet

www.ti.com

Low-Power Mode

28.4 Low-Power Mode

The SCI/LIN module can be put in either local or global low-power mode. Global low-power mode is

asserted by the system and is not controlled by the SCI/LIN module. During global low-power mode, all

clocks to the SCI/LIN are turned off so the module is completely inactive. If global low-power mode is

requested while the receiver is receiving data, then the SCI/BLIN completes the current reception and

then enters the low-power mode, that is, module enters low power mode only when Busy bit (SCIFLR.3) is

cleared.

The BLIN module may enter low power mode either when there was no activity on the LINRX pin for more

than 4s (this can be either a constant recessive or dominant level) or when a Sleep Command frame was

received. Once the Timeout flag (SCIFLR.4) was set or once a Sleep Command was received, the

POWERDOWN bit (SCIGCR2.0) must be set by the application software to make the module enter local

low-power mode. A wakeup signal will terminate the sleep mode of the LIN bus.

NOTE: Enabling Local Low-Power Mode During Receive and Transmit

If the wakeup interrupt is enabled and low-power mode is requested while the receiver is

receiving data, then the SCI/LIN immediately generates a wake-up interrupt to clear the

powerdown bit. Thus, the SCI/LIN is prevented from entering low-power mode and

completes the current reception. Otherwise, if the wakeup interrupt is disabled, the SCI/LIN

completes the current reception and then enters the low-power mode.

28.4.1 Entering Sleep Mode

In LIN protocol, a sleep command is used to broadcast the sleep mode to all nodes. The sleep command

consists of a diagnostic master request frame with identifier 0x3C (60), with the first data field as 0x00.

There should be no activity in the bus once all nodes receive the sleep command: the bus is in sleep

mode.

Local low-power mode is asserted by setting the POWERDOWN bit; setting this bit stops the clocks to the

SCI/LIN internal logic and registers. Clearing the POWERDOWN bit causes SCI/LIN to exit from local low-

power mode. All the registers are accessible during local power-down mode. If a register is accessed in

low-power mode, this access results in enabling the clock to the module for that particular access alone.

1383

SPNU562–May 2014 Serial Communication Interface (SCI)/Local Interconnect Network (LIN)

Module

Submit Documentation Feedback