PRODUCT OVERVIEW
The AD1893 SamplePort is a fully digital, stereo Asynchronous Sample Rate Converter (ASRC) that solves sample rate interfacing and compatibility problems in digital audio equipment. Conceptually, this converter interpolates the input data up to a very high internal sample rate with a time resolution of 300 ps, then decimates down to the desired output sample rate. The AD1893 is intended for 16-bit low cost, non-varispeed applications where low voltage, low power (i.e., battery-powered) operation is required. Refer to the AD1890/AD1891 data sheet for other products in the SamplePort family. This device is asynchronous because the frequency and phase relationships between the input and output sample clocks (both are inputs to the AD1893 ASRC) are arbitrary and need not be related by a simple integer ratio. There is no need to explicitly select or program the input and output sample clock frequencies, as the AD1893 automatically senses the relationship between the two clocks. The input and output sample clock frequencies can nominally range from 8 kHz to 56 kHz, and the ratio between them can vary from approximately 1:2 to 2:1.
The AD1893 uses multirate digital signal processing techniques to construct an output sample stream from the input sample stream. The input word width is 4 to 16 bits for the AD1893. Shorter input words are automatically zero-filled in the LSBs. The output word width is 24 bits. The user can receive as many of the output bits as desired. Internal arithmetic is performed with 22-bit coefficients and 27-bit accumulation. The digital samples are processed with unity gain.

FEATURES
   Low Cost
   LQFP and PDIP Packages
   3 V Supply Performance Specified—Very Low Power
   Automatically Senses Sample Frequencies—No Programming Required
   Rejects Sample Clock Jitter
   Accommodates Dynamically Changing Asynchronous Sample Clocks
   8 kHz to 56 kHz Sample Clock Frequency Range
   Approximately 1:2 to 2:1 Ratio Between Sample Clocks
   –96 dB THD+N at 1 kHz
   96 dB Dynamic Range
   Optimal Clock Tracking Control—Slow/Fast Settling Modes
   Linear Phase in All Modes
   Automatic Output Mute
   Flexible Four-Wire Serial Interfaces with Right-Justified
   Mode
   Power-Down Mode
   On-Chip Oscillator

APPLICATIONS
   Consumer CD-R, DAT, DCC, MD and 8 mm Video Tape
      Recorders Including Portables
   Digital Audio Communication/Network Systems
   Computer Multimedia Systems