January 1995

2

Philips Semiconductors

Product specification

Universal divider

HEF4751V

LSI

DESCRIPTION

The HEF4751V is a universal divider (U.D.) intended for

use in high performance phase lock loop frequency

synthesizer systems. It 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 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.

Fig.1 Pinning diagram.

SUPPLY VOLTAGE

See Family Specifications

HEF4751VP(N):

28-lead DIL; plastic (SOT117)

HEF4751VD(F):

28-lead DIL; ceramic (cerdip) (SOT135V)

HEF4751VT(D):

28-lead SO; plastic (SOT136A)

( ): Package Designator North America

RATING

RECOMMENDED OPERATING

−0,5 to + 18

4,5 to 12,5 V