I'm planning a project which involves an Arduino Uno R3 SMD controlling a larger light installation that is powered from a 24V PSU. When the installation is on, the Arduino will control a bunch of RGB LED strip contraptions, but during daylight hours, the lights will be turned off. A real time clock module on the Arduino will handle the timing of that.
The PSU in question, a Mean Well HRP-450-24, has a remote on/off function and a 5V standby rail, so I figured that instead of leaving it fully on 24/7, I could use the Arduino to turn it off when the 24V output is not needed. The PSU is turned off by a dry contact switch; I was thinking of simply using a transistor to short the switch pins on the PSU by connecting SW+ to the collector, SW- to the emitter and an Arduino output to the base of the transistor. Thus, the Arduino would simply turn off the PSU at day.
To do this, the Arduino would obviously have to be powered from the standby rail. The PSU's datasheet states that the voltage is actually 5V +/-5%, so I presume that trying to connect that directly to a 5V pin on the Arduino is not a good idea. As the voltage is too low to connect to Vin, I found a couple of DC-DC boosters, namely this and this.
The idea is to simply step the 5V output from the PSU to 9V, which would go to the Arduino Vin. Assuming 80% efficiency and considering that the max output of the PSU is 300mA, the Arduino would be able to draw max 240mA. I guess that this should be plenty; the only extra hardware it will have to power is the RTC module. It will drive a bunch of shift registers, but they have their own line drivers with a separate power source, so no significant current will be drawn from the output pins.
Does this reasoning make sense? Will it even work? Are there better ways to do it?
-CC
