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Fez Raptor maximum peripheral power draw


#1

So, I was looking around for information about how much current draw from peripherals the raptor is capable of supporting but didn’t see much on the specifications page or with forum searches. On my current project I’m driving a cp7 touch screen and a fairly large array of sensors. Of all the sensors the gas sensors concern me the most because the heater elements can draw +500ma and I’m using two of them driven from an AP5 hub that also is controlling 3 relays and a temperature sensor. I suppose the wifi and cp7 itself may also be candidates for being driven by a dedicated power supply as well.

I haven’t fired up the heater elements in my application yet because of the power concerns. Would it be wise to power the 2 gas sensors or the ap5 hub from their own power source rather than relying on power supplied to the ap5 from the main board? What power limitations have people run into when trying to power large amounts of sensors from their mainboard. Also I’m running the board on a 1 amp 12 volt power supply through the external power module.


#2

I never thought it was a power supply. It has to support the load of peripherals through the traces however. Id be willing to be you can’t pull more than an amp or two through the board itself. I’ve got a load that’s likely around 2 amps at 5 volts i cant support that with the external power module as it can only handle 1 amp at 5 volts. Rather than just hooking up a larger supply to the board I’m considering routing power from an external supply to the devices themselves and not relying on the board supplying power to them through a power module.


#3

The load itself will never be driven from the processor in a properly designed module. Each pin should be considered to deliver less than 40ma. In almost all cases, the pin itself it used to trigger a transistor that is connected to the power rails.

Nevertheless, you will still want to use a power extender for ‘hungry’ modules like the CP7 and Gas Sensors. WiFi etc should be fine with the use of the DP only :slight_smile:


#4

Thanks James I ordered a couple of power extender modules to run the screen and gas sensors. I guess I didn’t see it in the store when I did my initial buying spree for components for this project.