Overview
The SM5905AF is a compression and non compression type shock-proof memory controller LSI for compact disc players. The compression level can be set in 4 levels, and external 4M DRAM can be connected to expand the memory to 4M bits. Digital attenuator, soft mute and related functions are also incorporated. It operates from a 4.5 to 5.5 V supply voltage range.

FEATUREs
- 2-channel processing
- Serial data input
   • 2s complement, 16-bit/MSB first, right-justified
      format
   • Wide capture function
      (up to 3 × speed input rate)
- System clock input
   • 384fs (16.9344 MHz)
- Shock-proof memory controller
   • ADPCM compression method
   • 4-level compression mode selectable
      4-bit compression mode 2.78 s/Mbit
      6-bit compression mode 1.85 s/Mbit
      8-bit compression mode 1.39 s/Mbit
      Full-bit non compression mode 0.74 s/Mbit
   • External DRAM configurations usable
      2 × 4M DRAM (1M × 4 bits)
         Internal and External 4M DRAM
      1 × 4M DRAM (1M × 4 bits)
         Only Internal 4M DRAM
- Compression mode selectable
- Microcontroller interface
   • Serial command write and status read-out
   • Data residual detector:
      15-bit operation, 16-bit output
   • Digital attenuator
      8-bit setting
   • Soft attenuator function
      Noiseless attenuation-level switching
      (256- step switching in 23 ms max.)
   • Soft mute function
      Mute ON in 23 ms max.
      Direct return after soft mute release
   • Forced mute
- Extension I/O
   Microcontroller interface for external control
   using 4 extension I/O pins
- +4.5 to + 5.5 V operating voltage range
- Schmitt inputs
   All input pins (including I/O pins) except CLK
   (system clock)
- Reset signal noise elimination
   Approximately 3.8 µs or longer (65 system
   clock pulses) continuous LOW-level reset
- Digital audio interface (DIT)
- 44-pin QFP package (0.8 mm pin pitch)