Overview
The SM5903BF 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 memory can be selected from 4 options (1M, 4M, 4M× 2, 16M). It operates from a 2.4 to 3.6 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
        5-bit compression mode 2.22 s/Mbit
        6-bit compression mode 1.85 s/Mbit
        Full-bit non compression mode 0.74 s/Mbit
    • 4 external DRAM configurations selectable
        1 × 16M DRAM (4M × 4 bits, refresh cycle = 2048 cycle)
        1 or 2 × 4M DRAM (1M × 4 bits)
        1 × 1M DRAM (256k × 4 bits)
- Microcontroller interface
    • Serial command write and status read-out
    • Data residual detector:
        15-bit operation, 16-bit output
    • Forced mute
- Extension I/O
    Microcontroller interface for external control using 5 extension I/O pins
- +2.4 to +3.6 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
- 44-pin LQFP package (0.8 mm pin pitch)