LM1894 is a dynamic noise reduction circuit for use with audio playback systems. The DNR system non-complementary, meaning it does not require encodedis source material. The system is compatible with virtually all prerecorded tapes and FM broadcasts.
The LM1894 is a stereo noise‑reduction circuit designed for audio playback systems. It operates with a wide supply range (4.5 V‑18 V) and provides up to 10 dB of CCIR/ARM weighted noise reduction without requiring encoded source material. The device features low‑cost external components and a single‑ended architecture.
The datasheet includes absolute maximum ratings, electrical characteristics, typical performance curves, external component recommendations, circuit operation details, application hints, and physical dimensions for both SO (M14A) and DIP (N14A) packages.
| Operating Supply Range | 4.5 V to 18 V |
|---|---|
| Supply Current (typical) | 30 mA |
| Effective Noise Reduction (CCIR/ARM weighted) | ≈10 dB |
| Input Overload | 1 Vrms |
| Voltage Gain (typical) | -1 V/V |
The LM1894 can achieve about 10 dB of CCIR/ARM weighted noise reduction, with a maximum of roughly 14 dB in certain conditions.
The device operates over a wide supply range of 4.5 V to 18 V.
The LM1894 is offered in a Small‑Outline package (M14A) and a Dual‑In‑Line package (N14A).
Typical supply current is about 30 mA at an 8 V supply.