Datasheet
January 1995 2
Philips Semiconductors Product speciļ¬cation
Programmable timer
HEF4541B
MSI
DESCRIPTION
The HEF4541B is a programmable timer which consists of
a 16-stage binary counter, an integrated oscillator to be
used with external timing components, an automatic
power-on reset and output control logic. The frequency of
the oscillator is determined by the external components
R
t
and C
t
within the frequency range 1 Hz to 100 kHz. This
oscillator may be replaced by an external clock signal at
input RS, the timer advances on the positive-going
transition of RS. A LOW on the auto reset input (AR) and
a LOW on the master reset input (MR) enables the internal
power-on reset. A HIGH level at input MR resets the
counter independent on all other inputs. Resetting
disables the oscillator to provide no active power
dissipation.
A HIGH at input
AR turns off the power-on reset to provide
a low quiescent power dissipation of the timer. The
16-stage counter divides the oscillator frequency by
2
8
,2
10
,2
13
or 2
16
depending on the state of the address
inputs (A
0
,A
1
). The divided oscillator frequency is
available at output O. The phase input (PH) features a
complementary output signal. If the mode select input
(MODE) is LOW or HIGH the timer can be used
respectively as a single transition timer or 2
n
frequency
divider.
Fig.1 Functional diagram.
Fig.2 Pinning diagram.
FAMILY DATA, I
DD
LIMITS category MSI
See Family Specifications
HEF4541BP(N): 14-lead DIL; plastic
(SOT27-1)
HEF4541BD(F): 14-lead DIL; ceramic (cerdip)
(SOT73)
HEF4541BT(D): 14-lead SO; plastic
(SOT108-1)
( ): Package Designator North America