Overview
The LC75421M is an electronic volume controller that enables control of volume, balance, fader, bass/treble + super bass, input switching, and input and output level control functions using only a small number of external components.
Functions
• Volume: 0 dB to –79 dB in 1-dB steps, and –∞ (81 positions) Balance function with separate L/R control
• Fader: rear output or front output can be attenuated across 16 positions (in 2-dB steps from 0 dB to - 20 dB, 5-dB steps from –20 dB to –25 dB, 10-dB steps from –25 dB to –45 dB, and –60 dB, –∞)
• Bass/treble: A tone control circuit can be configured using an external RC, with 15-position control from 0 dB to ±11.9 dB in 1.7-dB steps possible for both bass and treble
• Input gain: 0 dB to +18.75 dB (1.25-dB steps) amplification is possible for the input signal.
• Output gain: Fader output can be selected among 0 dB, +6.5 dB, and +8.5 dB.
• Input switching: Five input signals can be selected for Left and for Right
• Super bass: Step control with 11 positions is possible, with peaking characteristics (type T)

FEATUREs
• On-chip buffer amplifier cuts down number of external components
• Low switching noise generated by on-chip switch due to use of silicon gate CMOS process
• On-chip reference voltage circuit for analog ground
• Controls performed with serial input (CCB)