M2-ATX: Car PC Power Supply

Logic Supply also provided the $89 M2-ATX, a 160-W dc-dc automotive power supply (see the Figure). This model can handle the heftier requirements of the Intel-based processors. A lower-power version is available in the same form factor for VIA-based motherboards that require less power. The power supply is also suitable for other rugged environments like boats or electric vehicles.

Don't even think about using a conventional power supply with an automotive PC. Transients are an issue as well as the power on/off cycle. Conventional power supplies require an on/off switch. They also require a much narrower input voltage range. The M2-ATX can handle input voltages from 6 V to 24 V. It also handles over-voltage situations that arise in automotive environments when the starter motor is turning over the engine.

The M2-ATX has eight user selectable timing modes that control the ignition/shutdown PC timing schemes provided by a built-in shutdown microcontroller. One mode is compatible with a traditional power-supply unit, but the others have different power on and off timings. These modes are critical because a motherboard draws at least a few hundred milliwatts in sleep/suspend mode. This can run down a car battery and make the driver very unhappy. The M2-ATX monitors the input voltage levels to prevent deep discharge situations by automatically shutting down the system until the battery returns to a safe level.

The M2-ATX provides up to 8 A on the 12-V rail necessary for Intel and AMD processors. There is a separate 4-pin, 12-V connector on the M2-ATX. Make sure you request the 12-V cable when you order this power supply from Logic Supply. It is not required if you use a VIA motherboard.