LM2240 Programmable Timer Counter
August 1990
LM2240
Programmable Timer Counter
General Description
The LM2240 Programmable Timer Counter is a monolithic
controller capable of both monostable and astable opera-
tion Monostable operation allows accurate microsecond to
five day time delays Long delays up to three years can
easily be generated by cascading two timers The timer con-
sists of a time-base oscillator programmable 8-bit counter
and control flip-flop An external resistor-capacitor (RC) net-
work sets the oscillator frequency and allows delay times
from 1 RC to 255 RC to be selected In the astable mode of
operation a single RC network sets the base frequency
The frequencies of the squarewaves at the 8 outputs are
each at different factors of 2 from the base frequency If 2 or
more of the outputs are shorted together various pulse pat-
terns can be generated These frequencies or pulse pat-
terns can also easily be synchronized to an external signal
The trigger reset and outputs are all TTL and CMOS com-
patible for easy interface with digital systems The timer鈥檚
high accuracy and versatility in producing a wide range of
time delays makes it ideal as a direct replacement for me-
chanical or electromechanical devices
Features
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Accurate timing from microseconds to days
Programmable delays from 1 RC to 255 RC
TTL and CMOS compatible outputs
Timing directly proportional to RC time constant
High accuracy
External sync and modulation capability
Wide supply voltage range
Excellent supply voltage rejection
Connection Diagram
16-Lead Molded DIP
TL H 10837 鈥?1
Top View
See NS Package Number N16E
Order Number LM2240N
C
1995 National Semiconductor Corporation
TL H 10837
RRD-B30M115 Printed in U S A