ST HCF4541B User Manual

HCF4541B

PROGRAMMABLE TIMER

■ 16 STAGE BINARY COUNTER

■ LOW SYMMETR. OUTPUT RESISTANCE,

TYPICALLY 100Ω at V

■ OSCILLATOR FREQUENCY RANGE :

= 15V

DC to 100KHz

■ AUTO OR MASTER RESET DISABLES

OSCILLATOR DURING RESET TO REDUCE POWER DISSIPATION

■ OPERATES WITH VERY SLOW CLOCK

RISE AND FALL TIMES

■ BUILT-IN LOW-POWER RC OSCILLATOR

■ EXTERNAL CLOCK (applied to pin 3) CAN

BE USED INSTEAD OF OSCILLATOR

■ OPERATES A S 2

FREQUENCY DIVIDER

OR AS A SINGLE-TRANSITION TIMER

■ Q/Q SELECT PROVIDES OUTPUT LOGIC

LEVEL FLEXIBILITY

■ CAPABLE OF DRIVING SIX LOW POWER

TTL LOADS, THREE LOW POWER SCHOTTKY LOADS, OR SIX HTL LOADS OVER THE RATED TEMP. RANGE

■ 5V, 10V AND 15V PARAMETRIC RATINGS

■ 100% TESTED FOR QUIESCENT CURRENT

AT 20V

■ MEETS ALL REQUIREMENTS OF JEDEC

JESD13B " STANDARD SPECIFICATIONS FOR DESCRIPTI ON OF B SERI ES CMOS DEVICES"

DIP SOP

ORDER CODES

PACKAGE TUBE T & R

DIP HCF4541BEY

SOP HCF4541BM1 HCF4541M013TR

DESCRIPTION

The HCF4541B is a m onolithic integrated circuit fabricated in Metal Oxide Semiconductor technology available in DIP and SOP packages. This device is composed of a 16-stages binary counter, an oscillator controlled by 2 external resistors and a capacitor, an o utput control logic and an automatic power-on reset circuit. The counter varies on positive-edge clock transition and it can be cleared by the MASTER RESET input. The output from this timer is the Q or Q output from the 8th, 13th, or 16th counter stage. The choice of the stage depends on the time

PIN CONNECTION

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HCF4541B

select inputs A or B (see frequency selection table). The output is available in one of the two modes that can be selected via the M ODE input pin 10 (see truth table). The output turns out as a continuos square wave, with a frequenc y equal to the oscillator frequency divided by 2

when this MODE input is a logic "1". When it is a logic "0" and after a MASTER RESET is started, and Q output has been selected, the output goes up to a high state after 2

N-1

counts. It remains in that state till another M ASTER RE SET pulse is apply or the mode input is a logic "1". The process starts by setting the AUTO RESET input (pin 5) to logic

"0" and switching power on . If pin 5 is set to logic "1", the AUTO RESET circuit is not enabled and counting cannot start till a positive MASTER RESET pulse is applied, returning to a low level. The AUTO RESET consumes a remarkable amount of po wer and should not be used if low power operation is wanted. The frequenc y of the oscillator depends on the RC network. It can be calculated using the following formula :

f = 1 / 2.3 R

TC CTC

where f is between 1KHz and 100KHz and RS > 10 KΩ and ≈2 RTC

INPUT EQUIVALENT CIRCUIT PIN DESCRIPTION

PIN No SYMBOL NAME AND FUNCTION

12, 13 A, B Time Select Input

4, 11 NC Not Connected

, C

1, 2

5 AR Auto Reset Input 6 MR Master Reset Input

10 MODE Mode Select Input

9 8 Q Output

Q/Q

SELECT

External Resistor, Capaci-

tor Connection External Resistor Con-

nection or External Clock Input

Output Selector

Negative Supply Voltage Positive Supply Voltage

RC OSCILLATOR CIRCUIT

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FUNCTIONAL DIAGRAM

FREQUENCY SELECTION TABLE TRUTH TABLE

HCF4541B

A B N. of Stages N

L L 13 8192

L H 10 1024 H L 8 256 H H 16 65536

LOGIC DIAGRAM

Count 2

5 Auto Reset On Auto Reset Disable 6 Master Reset Off Master Reset On

Output Initially Low

10 Single Transition Mode Recycle Mode

After Reset (Q)

STATE

Output Initially High

After Reset (Q

)

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