I started working on suitable designs for the product (USB wall socket); then realized that in India not all wall outlet panel boards were dimensionally same. They were specific to the manufacturer (brand). This was a problem! || Problem 1 ||
The approach I took was to study how many households were using which type of wall panels. I did a quick survey by talking to electrical shop owners, electricians in few localities and casually observing panels when I visited any places like hotels or office spaces. Through this exercise I gathered that largely there were two types of panel frames 1. Anchor Roma type 2. Legrand type. There were other types as well, but these two types were high runners in that region at that time. The Legrand type was used mostly in upper middle-class households whereas the Anchor Roma type was used by the middle class and the lower middle-class households.
So, I decided to make multiple variants of the product, starting with a product that was compatible with Anchor Roma formfactor. There were multiple reasons for starting with Anchor Roma form factor a. the volumes were higher b. the dimensions were slightly larger which gave extra flexibility with the circuit component heights (e.g. electrolytic capacitors and magnetics).
This of course had a trade off with plastic molding die dimensions and packaging dimensions, but at that time I did not give it that much thought. || Problem 2 ||
While selecting the right form factor was key, I also had to start working on the electrical circuit board, had to decide on the topology and based on the topology design the regulator. I also had to arrange the equipment to test the boards.
The product in a general sense was a typical AC-DC converter. We were only required to make sure the output power was sufficient to charge phones, while maintaining high efficiency and tolerating wider input voltage ranges.