Semiconductor
CD4541B
CMOS Programmable Timer
High Voltage Types (20V Rating)
Description
CD4541B programmable timer consists of a 16-stage binary
counter, an oscillator that is controlled by external R-C compo-
nents (2 resistors and a capacitor), an automatic power-on
reset circuit, and output control logic. The counter increments
on positive-edge clock transitions and can also be reset via the
MASTER RESET input.
The output from this timer is the Q or Q output from the 8th,
10th, 13th, or 16th counter stage. The desired stage is chosen
using time-select inputs A and B (see Frequency Select Table).
The output is available in either of two modes selectable via the
MODE input, pin 10 (see Truth Table). When this MODE input is
a logic “1”, the output will be a continuous square wave having
a frequency equal to the oscillator frequency divided by 2
N
.
With the MODE input set to logic “0” and after a MASTER
RESET is initiated, the output (assuming Q output has been
selected) changes from a low to a high state after 2
N-1
counts
and remains in that state until another MASTER RESET pulse
is applied or the MODE input is set to a logic “1”.
Timing is initialized by setting the AUTO RESET input (pin 5) to
logic “0” and turning power on. If pin 5 is set to logic “1”, the
AUTO RESET circuit is disabled and counting will not start until
after a positive MASTER RESET pulse is applied and returns
to a low level. The AUTO RESET consumes an appreciable
amount of power and should not be used if low-power operation
is desired. For reliable automatic power-on reset, V
DD
should
be greater than 5V.
The RC oscillator, shown in Figure 2, oscillates with a
frequency determined by the RC network and is calculated
using:
1
-
f =
----------------------------------
2.3 R
TC
C
TC
Where f is between 1kHz
and 100kHz
and R
S
≥
10k
Ω
and
≈
2R
TC
July 1998
Features
• Low Symmetrical Output Resistance, Typically 100Ω
at V
DD
= 15V
• Built-In Low-Power RC Oscillator
• Oscillator Frequency Range . . . . . . . . . . DC to 100kHz
• External Clock (Applied to Pin 3) can be Used Instead
of Oscillator
• Operates as 2
N
Frequency Divider or as a Single-
Transition Timer
• Q/Q Select Provides Output Logic Level Flexibility
• AUTO or MASTER RESET Disables Oscillator During
Reset to Reduce Power Dissipation
• Operates With Very Slow Clock Rise and Fall Times
• Capable of Driving Six Low Power TTL Loads, Three
Low-Power Schottky Loads, or Six HTL Loads Over
the Rated Temperature Range
• Symmetrical Output Characteristics
• 100% Tested for Quiescent Current at 20V
• 5V, 10V, and 15V Parametric Ratings
• Meets All Requirements of JEDEC Standard No. 13B,
“Standard Specifications for Description of ‘B’ Series
CMOS Devices”
Ordering Information
PART NUMBER
CD4541BF
CD4541BE
CD4541BH
CD4541BM
TEMP.
RANGE (
o
C)
-55 to 125
-55 to 125
-55 to 125
-55 to 125
PACKAGE
14 Ld CERDIP
14 Ld PDIP
Chip
14 Ld SOIC
PKG.
NO.
F14.3
E14.3
-
M14.15
Pinout
CD4541B (CERDIP, PDIP, SOIC)
TOP VIEW
R
TC
1
C
TC
2
R
S
3
NC 4
AUTO RESET 5
MASTER RESET 6
V
SS
7
14 V
DD
13 B
12 A
11 NC
10 MODE
9 Q/Q SELECT
8 OUTPUT
CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper IC Handling Procedures.
Copyright
©
Harris Corporation 1998
File Number
1378.1
1
HARRIS [ HARRIS CORPORATION ]
