Moving from SX to Prop and need advice / help
eagletalontim
Posts: 1,399
Hello all once again! I have a product I have been selling for the past 3 or 4 years that needs to be converted to the Prop since the SX will be gone soon. Since the Prop uses different programming and requires different power levels, I will be needing some help with a few things. First of all and most important, how and what do I use to power the Prop from a 12 to 14v DC vehicle battery? With the SX, I am using a 7805 which is 5v, so I need to drop the voltage lower. If anyone has a schematic of how to power the Prop 44 pin surface mount chip, could you post it please? I have a Prop proto board with a semi working prototype, but I would like to change up a few things to hopefully save some money since the Prop is quite a bit more expensive than the SX. My product controls solenoids that are either 30 ohm or 130 ohm and are naturally grounded to the chassis of the vehicle. I need to be able to reliably power the solenoids via a MOSFET or Transistor when triggered by the Prop. I would prefer a MOSFET since if I am not mistaken, can be driven directly from the Prop. The max amperage I am needing to supply is 1A worst case scenario... normal is 500ma. The problem I am running into with MOSFETs is I am not very knowledgeable about them and how to hook them up to supply a 12v + source if it is even possible. Any help is greatly appreciated!
Comments
There's a whole thread that started today on MOSFETs. I'm not one of those that drives them directly; I use a buffer to increase the gate voltage (well beyond 3.3v) to ensure than I have the lowest possible RDSon. My favorite circuit is posted in that thread.
I've attached a generic page one from three products that we're developing at EFX-TEK. No specific part #s for regulators as you will have to choose those to suit the current requirements of your application.