Overview

The LC72121 and the LC72121M and the LC72121V are high input sensitivity (20 mVrms at 130 MHz) PLL frequency synthesizers for 3 V systems. These ICs are serial data (CCB) compatible with the LC72131, and feature the improved input sensitivity and lower spurious radiation (provided by a redesigned ground system) required in high-performance AM/FM tuners.

Functions

? High-speed programmable divider

— FMIN: 10 to 160 MHz ... Pulse swallower technique (With built-in divide-by-2 prescaler)

— AMIN: 2 to 40 MHz ... Pulse swallower technique 0.5 to 10 MHz ... Direct division technique

? IF counter

— IFIN: 0.4 to 15 MHz ... For AM and FM IF counting

? Reference frequency

— One of 12 reference frequencies can be selected (using a 4.5 or 7.2 MHz crystal element) 1, 3, 5, 9, 10, 3.125, 6.25, 12.5, 15, 25, 50, and 100 kHz

? Phase comparator

— Supports dead zone control.

— Built-in unlocked state detection circuit

— Built-in deadlock clear circuit

? An MOS transistor for an active low-pass filter is built in.

? I/O ports

— Output-only ports: 4 pins

— I/O ports: 2 pins

— Supports the output of a clock time base signal.

? Operating ranges

— Supply voltage: 2.7 to 3.6 V

— Operating temperature: – 40 to 85°C

? Package

— DIP22S, MFP24S, SSOP24

? Comparison with the LC72131/M

— Serial data compatible (CCB)

— Identical pin functions

— Two VSS pins were added.

— The DIP version is pin compatible (VSS pins were inserted as the DIP22S NC pins.)

— The MFP product provides a modified pin assignment (The MFP20 package was replaced by an MFP24 package, and extra VSS pins were added.)

— The SSOP24 is a newly developed package that has the same pin assignment as the MFP24S product.