ELM381 Datasheet, PDF (1/4 Pages) ELM Electronics – 60 Hz Long Interval Counter

ELM381
60 Hz Long Interval Counter
Description
The ELM381 is a digitally configurable, multi-
stage counter circuit in a single 8 pin package. When
connected to a 60Hz source, four time periods from
one hour to one week are possible, as shown in
Table 1 below.
Although the circuit has been optimized for a
60Hz input frequency, it is capable of being operated
over a very wide range of frequencies. Of particular
interest is the ability to interface directly to very low
frequencies with varying waveforms due to the use
of a Schmitt trigger input circuit.
The ELM381 provides two outputs – a standard
50% duty cycle divider output, and a momentarily
pulsed output. The pulse output is useful for audibly
or visually signalling the beginning of a time period,
or as a trigger for other circuitry. Refer to the
Example Applications section for two typical circuits.
Applications
• Long term (daily or weekly) event timers
• Missing event detectors
• Automatic shutoff circuits
Features
• Low power CMOS design - typically 1mA at 5V
• Wide supply range – 3.0 to 5.5 volt operation
• Digitally selectable delays
• Schmitt trigger circuitry on the clock input
• Completely static operation
• Long term accuracy with line frequency clock
• High current drive outputs – up to 25 mA
• Reset input provided with a pullup resistor
Connection Diagram
PDIP and SOIC
(top view)
VDD 1
D1 2
D0 3
reset 4
8 VSS
7 Out
6 Pulse
5 Clock
Block Diagram
VDD
Clock 5
VSS
D1 ²
D0 ³
reset
VDD
4
ELM381DSA
Digital
Counters
Pulse
Generator
7 Out
6 Pulse
Setting
D1 D0
L
L
L
H
HL
HH
Divisor
x 1000
216
2592
5184
36,288
Table 1
Elm Electronics – Circuits for the Hobbyist
< http://www.elmelectronics.com/ >
Period
(60Hz)
1 hour
12 hrs
24 hrs
7 days
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