Engine Cranks, under-voltage and over-voltage situations
. Another difficult task is maintaining stable 3.3V, 5V, 12V and
-12V power to your PC. While 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 (while car is running) but extra
precautions need to take place in order to prevent such situations. M2ATX can operate as low as 6V and as high as 28V
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 M2-ATX has an ‘anti-thump’ control that will keep your amp OFF while the PC starts. Simply
connect J6 to your amplifier remote control pins to activate the ‘anti-thump’ feature.
2.0
Mode of operation
The M2-ATX performs several timing routines and takes actions as follows:
(
NOTE
: When all config jumpers are removed, M2-ATX will be in the “dumb PSU mode”,
no ignition timing, no HARDOFF. M2-ATX will send a gratuitous “ON” pulse to the M/B
when power is applied for the first time. Do not connect J8/J9 to the M/B on/off switch if
you don’t want your PC to be started automatically.
1) Ignition=OFF. Nothing happens. M2-ATX is waiting for ignition signals.
2) Ignition=ON. M2-ATX waits for 2-3 seconds then turns on the 5Vsb rail. After another second M2-ATX sends an
“ON” signal to the motherboard via the 2 wires connected to the motherboard’s ON/OFF pins. The motherboard
will turn ON and your system should start booting.
3) Ignition=ON during driving. Your computer will remain ON.
4) Ignition=OFF. M2-ATX waits for “OFFDELAY” in seconds (see jumper chart on Page 2) and then it turns the
motherboard OFF by sending a signal to the motherboard’s ON/OFF switch. Your computer should turn off
gracefully (shutdown procedure). During this time, power will still be available for your PC to perform shutdown.
5) 5VSB will still be provided for another “HARDOFF” seconds (see jumper chart). In the event where the shutdown
process is longer than “OFFDELAY” (windows gets frozen, etc), power will be shut down hard, turning off all power
rails. If “HARDOFF” is set to ‘NEVER”, the PSU will always provide 5VSB, therefore the PC can also be used in the
SLEEP mode. During the HARDOFF procedure, the battery levels will be constantly monitored to prevent deep
discharge situations.
6) M2-ATX will go to step 1, if ignition is tuned ON again.
3.0
Troubleshooting
a) Motherboard is not turning ON.
Check input cables. Measure voltage on the un-switched 12V. You should get about 12V. Measure the un-switched pin
(red) while turning the car ON/OFF. You should see 12V (car on) or 0V (car off).
b) Motherboard is not turning ON (cont).
Check your output cables. Ensure total system power consumption does not exceed the M2-ATX specifications.
c) Motherboard is not turning ON (cont).
Make sure that either J8 or J9 is properly connected to the ON/OFF switch of your M/B.
4.0
M2-ATX Spezifications
