Overview

The LA1781M integrates all six blocks required in a car radio tuner on a single chip.

Features

• Improved noise reduction methods

The FM front end provides excellent 3-signal characteristics equivalent to those of the LA1193M.

Superlative listenability due to improved medium and weak field noise canceller characteristics.

Improved separation characteristics.

Anti-birdie filter.

Improved AM and FM thermal characteristics.

Excellent FM signal meter linearity.

Modified N.C. circuit for improved noise rejection.

• Double conversion AM tuner (up conversion)

Reduces the number of external components required as compared to earlier double conversion tuners, in particular, no crystal is required (when used in conjunction with the LC72144).

• Sample-to-sample variation reduction circuit built into the FM IF circuit. (Fixed resistors are used for the SD, keyed AGC, mute on adjustment, ATT, SNC, and HCC functions.)

• The LA1781 inherits the block arrangement of the LA1780M and supports pin-compatible designs.

Functions

• FM front end

• FM IF

• Noise canceller

• Multiplex

• AM up-conversion

• FM/AM switch • MRC