TEA0678 is a bipolar integrated circuit that provides two channels of Dolby B noise reduction for playback applications in car radios. It includes head and equalization amplifiers with electronically switchable time constants. Furthermore it includes electronically switchable inputs for tape drivers with reverse heads. This device also detects pauses of music in Automatic Music Search (AMS) mode, with a delay time fixed externally by a resistor. The short-circuit proof output stage of the TEA0678 is differential and provides muting. The device will only output a signal when both NR channels are active.
The Philips TEA0678 is a bipolar integrated circuit designed to provide two channels of Dolby B-type noise reduction for playback applications in car radios. The device includes head pre-amplifiers with reverse head switching capabilities and an Automatic Music Search (AMS) function that detects pauses in music.
| Number of channels | Dual (two) |
|---|---|
| Signal-to-noise ratio | 78 dB |
| Package type | SDIP32 plastic shrink dual in-line package |
| Operating temperature range | -40 to +85 °C |
Noise Reduction (NR) is enabled when pin NR/AMS is connected to ground.
Automatic Music Search (AMS) is enabled when pin NR/AMS is connected to HIGH (5 V).
Dolby noise reduction operates correctly if 0 dB Dolby level is adjusted at 387.5 mV.