The Industry's First Single-Chip MP3 Decoder LSI for USB/SD Memory

ROHM has recently developed the industry's first LSI that combines USB Memory/SD Card Host functionality, an MP3 audio decoder, and system controller on a single chip, reducing costs along with the number of parts required, resulting in increased board space. In addition, the system controller is equipped with command software that can perform file searching, reading, decoding, and can switch between standalone and slave operation, minimizing development time. Slave mode allows software control by the microcontroller for complex processes such as filename and ID3 tag display, while standalone mode provides MP3 functionality to non-audio applications - even those without a CPU. The BU9435KV enables automatic playback of MP3 files stored on USB or SD memory, making it ideal for all types of audio devices, such as CD players, compact stereo systems, car audio, and clock radios(Sample Price; 160 US$).

· Main features of the BU9435KV:

1. Integrated USB2.0 Full Speed host and SD memory card interfaces
2. Built-in MP3 decoder capable of reading ID3 tag information such as file/folder number, playback time, artist name, album name, and song title
3. Equipped with system controller with command software
4. Compatible with FAT16/FAT32 file systems
5. Switch between standalone/slave operation
6. Internal I²C Bus interface
7. 4×3 key matrix control
8. 7-channel LED control built in
9. Integrated auto-sampling rate conversion
10. Built-in parametric equalizer

· Terms

• USB2.0 Full Speed:
  An upgraded version of USB1.1, this standard offers rapid data transfer speeds of up to 480Mbps. There are three USB2.0 transfer modes: Low Speed Mode (1.5Mbps), Full Speed Mode (12Mbps), and High Speed Mode (480Mbps). USB2.0 provides sufficient performance, even when connected to storage devices such as HDDs.
• SD Memory Card:
  A Flash memory-based compact memory card developed jointly by Matsushita, SanDisk and Toshiba. SD Memory provides Category 3 SDMI copyright protection and encrypts/decrypts data between compatible devices and media by mutual recognition.
• MP3 and MP3 Decoder:
  MP3 is an audio file format for compressing digitized audio. At normal levels, MP3 can compress CD audio (PCM) to about 1/10 the size of the original data. An MP3 decoder uncompresses MP3 audio files for playback.
• ID3 TAG:
  A tagging format for MP3 that allows metadata such as the song title, artist, and track number to be stored in an MP3 file. This information can be created and changed using compatible software. ID3 TAG-compatible players can display this information during playback.
• FAT16/FAT32 File System:
  Windows-based file systems. FAT16 divides the disk into 2¹⁶ (65,536) sections, while FAT32 organizes the disk into 2³² (about 4.2 billion) sections for operating system management. FAT16 and FAT32 can handle up to 2GB and 2TB, respectively.
• Sampling Rate:
  The sampling rate indicates how many times per second an analog signal is converted into digital. The sampling rate for audio CDs is 44.1kHz.
• Parametric Equalizer:
  Divides the audio frequency band into sections in order to make it possible to adjust the amplification/attenuation individually. Refers to an equalizer that is capable of independently changing the frequency or bandwidth of the pass band.
• Slave Operation:
  A device that is controlled by another system or device.

	The Audio Decoder LSI