We need a circuit and PCB design for a 5 volt power supply with a battery charge and supply circuit to provide power when the input voltage fails. In effect this is a small simple 5 volt UPS, without any fancy "on battery" or "supply fail" outputs other than a couple of LED indicators.
The battery circuit must disconnect the battery at a defined voltage to prevent full discharge and cell damage when using a sealed lead acid battery and it must also prevent overcharge of the cell.
The 5 volt output must have a timer, so that the supply will only switch on 30 seconds after power is supplied to the input.
Input range 12 to 48 volts.
Output 5 volts @ 1 or 2 amps.
Battery is to be connected externally, voltage and capacity variable depending on desired run time.
The overall purpose is to produce a small, robust and cheap device.
1. Circuit design
2. Gerber, solder resist, component layout and drill files to manufacture PCB
3. Parts list
4. Sample PCB for test.