Overview
The LA4168M is a record/playback system IC for microcassette and compact cassette recorders. The LA4168M is an extremely high-functionality IC that includes a motor control governor circuit, a voice sensor circuit that detects sounds and turns motor on or off, a power switch control circuit that receives an electrical signal from a photosensor and turns all of the IC function blocks on or off, and a circuit that increases the speed of the motor during playback.

Features
• Includes a voice switch that can turn the governor on or off.
• Includes a power switch circuit that can turn all the IC function blocks on or off from a photosensor signal. During record, the IC can automatically turn the governor on or off according to the microphone input level, and furthermore, the governor on/off level can be continuously adjusted from an external control knob. (The control used for volume adjustment during playback.)
• Continuously variable microphone monitor level.
• Includes a drive pin for an LED that lights only when the governor is on in record mode.

Functions
• Microphone and playback preamplifiers
• Record amplifier
• Power amplifier (BTL, 4 Ω)
• Automatic stop circuit (power switch)
• Governor circuit
• Motor speed and high-speed switching circuit
• Microphone power supply
• LED drive circuit
• Voice sensor circuit