PicoPSU-120 & PW-200M
These units are designed to power a miniITX motherboard, such as the VIA EPIA-series motherboards. They are small (especially the PicoPSU), which gives them a decided advantage for vehicle installations, where space is usually at a premium.
However, these units do not regulate the 12v line. That means that whatever voltage goes into the power supply is also fed to any 12v devices that are connected to the power supply.
You might be asking why this is so bad, since a car's electrical system is also 12v. True, but the car's electrical system fluctuates quite a bit. The power output will drop to around 9-10v when you crank the engine, as most of the power is fed to the starter. When the car is running and the battery is fully charged by the alternator, the voltage typically runs around 14v or even higher.
When the voltage drops below a certain level, a motherboard will simply shut off. When the voltage is too high, it will destroy components.
The advantage to these tiny PSUs is that there's no maximum output for the 12v line, because it's not regulating it. The maximum is only deetermined by the components it's made of. However, in a vehicle, you want a steady, regulated 12v current going into one of these power supplies. One maker of regulators specifically for vehicle computing applications is Carnetix.
Mini-box.com is also producing new versions of the PicoPSU line that accept a wider range of voltages, which are more suited for a vehicle environment. they have the same features as the PicoPSU above, except for the ability to accept a range of input voltages. Because of the low output wattage, the PicoPSU is only suggested for very low-power systems such as those based on the lower-end Via C3-based motherboards like the M10000.
PicoPSU-60-WI
60 watts / 80 watt peak
6-26V wide input
There are also 90w & 120w variations of the PicoPSU WI series, but they are not as well-suited for a vehicle application, as they require a minimum input voltage of 14v & 12v respectively. Because the voltage of a typical car 12v electrical system will drop below the 12v threshhold, these are not recommended.
Carnetix Power Supplies
Carnetix realized the shortcomings of these widely distributed micro power supplies and made a product to work in conjunction with them. The term 'power supply' isn't entirely accurate. They act more as a regulator to provide a consistent 12v stream of power to a PSU that isn't regulated, such as the PW-200M and others.
The CNX-P1260 provides 5A of 12v current, for a maximum output of 60w.
The CNX-P1290 provides 6.3A of 12v current, for a maximum output of 75.6w. It also provides 3A of 5v current (15w) for those devices that require it.
They also make a different product line that includes the CNX-P1900 and P2140. These are designed for mini-PCs like some small formfactor HP units, Mac Mini, Cappuccinos and the like that have a 'transformer brick' type of power supply. They also work very well with many models of laptop that require a single input voltage. The CNX-P1900 & P2140 provide a user-selectable consistent voltage of 18v, 19v or 20v, as well as a secondary output of 12v, 13.5v or 5v.
For building a system based on one of these miniature systems or a laptop, these power supplies will give you all the bells and whistles as the better ATX power supplies from Opus Solutions, including a startup/shutdown controller, acceptance of a remote turn-on from a car stereo or car alarm and more.
CNX-P1900
+18v @ 6.32A (113.76w)
or +19v @ 6.32A (120.08w)
or +20v @ 6.32A (126.4v) [Primary output]
+5v @ 3A (15w)
or +12v @ 3A (36w) [Secondary output]
(Be aware that use of the secondary output at 12v will detract from the current available on the primary output!)
CNX-P2140
+12v @ 11A (132w)
or +18v @ 7.5A (135w)
or +20v @ 7.5A (150w) [Primary output]
+5v @ 3A (15w)
or +12v @ 3A (36w) [Secondary output]
+5v @ 3A (15w)
or +12v @ 3A (36w) [
OPTIONAL third output]
(Be aware that use of the secondary output at 12v will detract from the current available on the primary output! The CNX-P2140 also has the ability to accept 24v input to allow for greater primary output amperage. Consult the
user manual for more details.)
Carnetix has gone to great lengths to write an excellent document about how to choose the correct power supply for your vehicle PC project. It's freely available on their website here:
http://www.carnetix.com/regulators/h...coose_psu.html
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Linear Mode
