HEF4751V

Pinout




Description

The HEF4751V is a universal divider (U.D.) intended for use in high performance phase lock loop frequency synthesizer systems. HEF4751V consists of a chain of counters operating in a programmable feedback mode. Programmable feedback signals are generated for up to three external (fast) ÷ 10/11 prescaler.

The system comprising one HEF4751V U.D. together with prescalers is a fully programmable divider with a maximum configuration of: 5 decimal stages, a programmable mode M stage (1 M 16, non-decimal fraction channel selection), and a mode H stage (H = 1 or 2, stage for half channel offset).Programming is performed in BCD code in a bit-parallel,digit-serial format.

To accommodate fixed or variable frequency offset, two numbers are applied in parallel, one being subtracted from the other to produce the internal programme.  The decade selection address is generated by an internal programme counter which may run continuously or on demand. Two or more universal dividers can be cascaded,each extra U.D. (in slave mode) adds two decades to the system. The combination of HEF4751V retains the full programmability and features of a single U.D. The U.D. provides a fast output signal FF at output OFF, which can have a phase jitter of ± 1 system input period, to allow fast frequency locking. The slow output signal FS at output OFS, which is jitter-free, is used for fine phase control at a lower speed.