The DNA 25 chip is made by a company called Evolv. Evolv describe the chip on their website:
The DNA 25 is the DNA 40’s less expensive little brother. The DNA system lets anyone build Evolv’s patented power regulated technology into their own products. The DNA 25 is a power regulated digital switch-mode DC-DC converter for personal vaporizers. It features Evolv’s patented Wattage Control, Temperature Protection, Preheat, Step Up/Step Down Topology, Digital User Controls, OLED Screen, Onboard Buttons and Synchronous Rectification for maximum battery life and minimal heat generation.
The DNA 25 is the same size as the DNA 40.