APN337S3959 Infineon Apple MFi Authentication Coprocessor I2C USON-8

The APN337S3959, also identified in public sources as MFI337S3959, is a dedicated authentication coprocessor used in Apple MFi accessory systems. It is commonly listed through component supply channels under Infineon and is designed to support secure authentication between authorized accessories and compatible Apple devices.

The device communicates with a host controller through an I2C serial interface and supports an SCL clock frequency from approximately 10kHz to 400kHz. Its recommended operating supply range is 1.62V to 5.5V. The coprocessor handles authentication-related operations including certificate data, challenge processing, and digital signature functions.

APN337S3959 is supplied in a compact 8-pin USON/QFN-type surface-mount package. Public information for the corresponding MFI337S3959 device indicates a compact package of approximately 2.5 × 2.5mm and a recommended operating temperature range of about -25°C to +85°C.

Typical applications include Apple MFi-authorized accessories, audio products, smart speakers, docking systems, automotive electronics, and other equipment requiring hardware-based Apple accessory authentication. Because this is a proprietary authentication component, designers should verify MFi authorization, sourcing, and hardware compatibility before integration.