Systems and methods for financial transaction through miniaturized card with ASIC

A card reader device is provided with a housing having a slot for swiping a magnetic stripe of a card to complete a financial transaction between a buyer and seller. A read head is in the housing reads data stored on the magnetic stripe and produces a signal indicative of data stored on the magnetic stripe. An output jack is adapted to be inserted into a microphone input associated with a mobile device for provides the signal indicative of data stored on the magnetic stripe to the mobile device. A sourcing power device couples to an audio jack of the mobile device and sources power from the mobile device through the audio jack.