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M3-ATX-HV User Guide Page 3
P1: Sends ON pulse to motherboard when ignition is ON for more than 2
seconds, sends OFF pulse to motherboard 5 seconds after ignition is turned
off. Waits another 1 minute and then shuts down 5VSB to conserve battery. In
this mode, the M3-ATX-HV consumes less than 0.5mA. This is our
recommended setting.
P2: Sends ON pulse to motherboard when ignition is ON for more than 2
seconds, sends OFF pulse to motherboard 60 seconds after ignition is turned
off. Waits another 5 minutes and then shuts down 5VSB to conserve battery.
P3: Sends ON pulse to motherboard when ignition is ON for more than 2
seconds, sends OFF pulse to motherboard 30 minutes after ignition is turned
off. Waits another 2 hours and then shuts down 5VSB to conserve battery.
P4: Can be set to any value. Setting can be done via an optional serial cable.
(Default values for P4 are Off-delay=30sec, Hard-off=30sec)
NOTE: To reset to the M3-ATX-HV settings to the factory defaults (in case
changes were made via the serial uplink), simply power off the unit, connect a
jumper as shown and then power back up. The LED light will start to flash
rapidly indicating that the factory defaults were loaded. Don’t
forget to Remove jumper when done!.
Power challenges in a Vehicle PC: One of most difficult tasks of operating a
PC in a vehicle is power consumption while the computer is OFF. Even when
your computer is OFF, it will still consume about 100mA on the 5V rail. When
the computer is in the suspend mode, it will consume even more power,
because the RAM needs to be powered at all times. No matter how big your
battery is, you will eventually drain it if proper actions are not taken.
The M3-ATX-HV is addressing these issues by cutting off the 5VSB rail after a
pre-defined amount of time (see jumper chart, HARDOFF). During the
HARDOFF if the battery level drops below 11.2V for more than one minute, M3-
ATX-HV will shut down and re-activate only when the input voltage is > 12V.
Engine Cranks, under-voltage and over-voltage situations. Another difficult
task is maintaining stable power to your PC. While most car batteries are rated
at 12V, they actually provide voltages in between 7-11V (engine cranks) or as
high as 80 volts (load dump). Most of the times, your battery will stay at 13.5V
or 27V (while car is running) but extra precautions need to take place in order to
prevent such situations. M3-ATX-HV can operate as low as 6V and as high as
34V while providing strict regulation on all rails along with input voltage
clamping and reverse protection.
Loud amplifier pops when PC starts. If your PC is connected to your car
amplifier, you will hear a loud pop when the computer is first started. The M3-
ATX-HV has an ‘anti-thump’ control that will keep your amp OFF while the PC
starts. Simply connect the white wire from your M3-ATX-HV cable harness to
your amplifier remote control pin.
