The AS3394E is a complete analog music synthesizer voice-on-a-chip
intended for software control by a microprocessor system. Included
inside the compact 24 pin package is fully temperature compensated, wide
range, voltage controlled oscillator providing suboscillator, triangle,
sawtooth, and pulse waveforms; a voltage controlled mixer for adjusting
the balance between the internally generated VCO waveforms and any
external signal; a dedicated four-pole low-pass voltage controlled
filter with voltage controlled resonance; a modulation amount VCA for
modulating the filter frequency by the triangle waveform output of the
VCO; and a final VCA for allowing the output to be enveloped. Envelope
control for both the VCF and final VCA may be provided by either a
hardware envelope generator such as the AS3310 or through software.
Ranging between -4 and +4 volts, all eight control inputs are provided
with internal very high input impedance, low bias current buffers. Thus
interface to a microprocessor system may be accomplished simply with a
single DAC, 4051-type CMOS multiplexer, and 8 hold capacitors.
Requiring a bare minimum of other external components, the AS3394E is
ideal for polyphonic or polytimbric musical instruments
featuring rich, analog sound.