LM2240N National Semiconductor, LM2240N Datasheet

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LM2240N

Manufacturer Part Number
LM2240N
Description
Programmable Timer/Counter
Manufacturer
National Semiconductor
Datasheet
C 1995 National Semiconductor Corporation
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’s
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
Connection Diagram
TL H 10837
See NS Package Number N16E
16-Lead Molded DIP
Order Number LM2240N
Top View
Features
Y
Y
Y
Y
Y
Y
Y
Y
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
TL H 10837 – 1
RRD-B30M115 Printed in U S A
August 1990

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LM2240N Summary of contents

Page 1

... TTL and CMOS compatible outputs Y Timing directly proportional to RC time constant Y High accuracy Y External sync and modulation capability Y Wide supply voltage range Y Excellent supply voltage rejection Y 16-Lead Molded DIP TL H 10837 – 1 Top View See NS Package Number N16E Order Number LM2240N August 1990 RRD-B30M115 Printed ...

Page 2

... Absolute Maximum Ratings If Military Aerospace specified devices are required please contact the National Semiconductor Sales Office Distributors for availability and specifications Storage Temperature Range Molded DIP Lead Temperature Molded DIP (Soldering 10 Sec ) Power Dissipation (Note 2) Junction Temperature LM2240 Electrical Characteristics Symbol ...

Page 3

Electrical Characteristics Symbol Characteristic TRIGGER RESET CONTROLS V Trigger Threshold TR I Trigger Current TR Z Trigger Impedance T t Trigger Response Time RSPT ...

Page 4

Typical Performance Characteristics Supply Current vs Supply Voltage in Reset Condition Minimum Trigger and Reset Pulse Widths vs Trigger and Reset Amplitude Normalized Change in Time-Base Period vs Modulation Voltage Recommended Range of Timing Component Time-Base Period Values (Note 7) ...

Page 5

Functional Description V Pin GND Pin 9 e FIGURE 1 Logic Symbol When power is applied to the LM2240 with no trigger or reset inputs activated the circuit starts with all outputs HIGH Application of a positive ...

Page 6

Circuit Controls Counter Outputs (O O Pins1 thru 8) 0 128 The binary counter outputs are buffered open collector type stages as shown in the block diagram Each output is capa- ble of sinking ...

Page 7

Circuit Controls (Continued) V Pin GND Pin 9 e FIGURE 6 Low Power Operation of Cascaded Timers Monostable Operation Precision Timing In precision timing applications the LM2240 is used in its monostable or self-resetting mode The generalized ...

Page 8

Astable Operation (Continued) V Pin GND Pin 9 e FIGURE 7 Cascaded Operation for Long Delays Binary Pattern Generation In astable operation as shown in Figures 8 and 9 the out- put of the LM2240 appears as ...

Page 9

Astable Operation (Continued) V Pin GND Pin 9 e FIGURE 11 Astable Operation Examples of Output 10837 – 14 ...

Page 10

... Hong Kong Ltd 49) 0-180-530 85 86 13th Floor Straight Block a Ocean Centre 5 Canton Rd 49) 0-180-530 85 85 Tsimshatsui Kowloon a Tel ( 49) 0-180-532 78 32 Hong Kong a 49) 0-180-532 93 58 Tel (852) 2737-1600 a Tel ( 49) 0-180-534 16 80 Fax (852) 2736-9960 a National Semiconductor Japan Ltd Tel 81-043-299-2309 Fax 81-043-299-2408 ...

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