SAM3S, SAM3N, SAM4N, and the SAM4S are pin to pin compatible, offering easy portability and allowing the customer to scale its needs in performance. It is really easy to migrate or start developing on one series then move to the other. For applications with high pin count but with limited PCB space needs, Microchip has a 7 x 7mm BGA package. The WLCSP package offers the smallest package with up to 64 pins.