Philips Semiconductors
Product specification
Programmable divide-by-n counter
Figure 3 illustrates the operation of the counter in mode
÷
8 starting from the preset state 3.
HEF4059B
LSI
CP INPUT
K
c
INPUT
(K
a
, K
b
= LOW)
internal state
of counter
O OUTPUT
Fig.3 Total count of 3.
If the ‘master preset’ mode is started two clock cycles or
less before an output pulse, the output pulse will appear at
the time due. If the ‘master preset’ mode is not used the
counter is preset in accordance with the ‘jam inputs when
the output pulse appears. A HIGH level at the latch enable
input (EL) will cause the counter output to go HIGH once
an output pulse occurs, and remain in the HIGH state until
EL input returns to LOW. If the EL input is LOW, the output
pulse will remain HIGH for only one cycle of the clock input
signal.
When K
a
= L, K
b
= H, K
c
= L and EL = L, the counter
operates in the ‘preset inhibit’ mode, with which the
dividend of the counter is fixed to 10 000, independent of
the state of the jam inputs.
When in the same state of mode select inputs EL = H, the
counter operates in the normal
÷
10 mode, however,
without the latch operation at the output.
Schmitt-trigger action in the clock input makes the circuit
highly tolerant to slower clock rise and fall times.
January 1995
4
PHILIPS [ NXP SEMICONDUCTORS ]
