Vehicle Power Management; Power Management Mechanism - Advantech TREK-753 User Manual

5.4 Vehicle Power Management

5.4.1 Power Management Mechanism

The feature of Vehicle Power Management (VPM) is provided for users to fulfill the
special requirements on in-vehicle applications.
Ignition on/off
– Turn on the system by ignition
For the cases of in-vehicle applications, an ignition signal is often used to turn
on or shutdown the system. When the system is in an OFF state and ignition
is turn ON, the VPM controller will countdown ON_DELAY; once it counts to
zero, the system will be turned on.
– Shutdown the system by ignition
When the system is powered on and the ignition is turn off, the
OFF_EVENT_DELAY will start to count down. During this stage, if the igni-
tion is back to ON, the VPM controller will stop countdown and reset the
OFF_EVENT_DELAY value. If OFF_EVENT_DELAY counts to zero, the
VPM controller will send an event (power button press) to the system and
start to count HARD_OFF_DELAY. Application programs could watch this
event to do pre-defined tasks, like storing data and preparing to turn off the
system.
Once going into the HARD_OFF_DELAY stage, this process will be irrevers-
ible. And if HARD_OFF_DELAY counts to zero, the system power will be cut
off abruptly.
Low battery protection
To avoid draining out the car battery, low-battery protection is involved to ensure
the car battery is capable to start the vehicle. When the system is ON, the VPM
controller will monitor the car battery voltage. If the battery voltage is lower than
a programmable threshold (LOW_THRESHOLD), the VPM controller will go into
LOW_DELAY stage and start to count down. During the stage of LOW_DELAY
countdown, if battery voltage is back above LOW_THRESHOLD, the VPM con-
troller will stop counting down and exit. If LOW_DELAY counts to zero, the VPM
controller will send an event (power button press) to notify the system, go into
LOW_ HARD_DELAY stage and start to count down. Once LOW_
HARD_DELAY counts to zero, the VPM controller will cut off the system power
abruptly to avoid draining out the car battery.
The table below lists the user programmable parameters for VPM features:
ON_DELAY
OFF_EVENT_DELAY
HARD_OFF_DELAY
LOW_THRESHOLD (12V mode)
LOW_THRESHOLD (24V mode)
LOW_DELAY
LOW_ HARD_DELAY
TREK-753 User Manual
Default value Acceptable range
2 seconds 1 ~ 18000 seconds
5 seconds 1 ~ 18000 seconds
60 seconds 1 ~ 18000 seconds
11.42 V 10.09 ~ 12.25 V
22.44 V 21.11 ~ 23.28 V
30 seconds 1 ~ 3600 seconds
60 seconds 1 ~ 3600 seconds
40