I am having trouble of converting AC supply to 9V-15V DC supply
I know one can do the conversion by using a transformer and a bridge rectifier, but buying a transformer is costly and space consuming.
So I wonder, is there any off the shelf IC which can do this? I just want to use the DC voltage to power a PIR (passive infra-red) and a 555 timer...under 30mA
You can provide unisolated power but for safety reason a transformer is recommended.
But .. for I≤30mA:
You have to connect 6800Ω(10W) resistor or 470nF(rated for 250Vac) capacitor to Active (230Vac) in series with a rectifier diode (rated for 400V) and 10V zener diode between rec. diode and Neutral. You will have to add a smoothing capacitor, say, 100µF/63V .. and here is your supply voltage ..
You have no isolation, and a transformer presents one, from dangerous mains voltage. In "open circuit" situation you are exposed to full 230Vac ..
I don't know of any IC without external components that will convert 230Vac to 10(or so) Vdc @ 30mA ..
There are some ics making conversion isolated or nonisolated but they need external components and/or transformer. But transformer will be smaller due to high frequency. But it will also cost more than a linear supply. If you don't care isolation then you should consider IanP's suggestion as you need low power.
there's no magic, you have to sacrifice some board space for this purpose.
I wonder if u wanted just a crude supply and up to 30mA of current, why couldn't u get it from ur system supply? u got to have one, otherwise, where is your system powered from?
However, i do not know ur app, u may have specific reasons to do so.
I am sure the simplest and most area effective method has been presented to u, you may not want to waste time to explore an IC solution.