VDD (pin 1)
This pin is the positive supply pin, and should
always be the most positive point in the circuit.
Internal circuitry connected to this pin is used to
provide power on reset of the microprocessor, so
an external reset signal is normally not required.
Refer to the Electrical Characteristics section for
D1 (pin 2) and D0 (pin 3)
The logic levels on these pins control the divider
ratio, as shown in Table 1. Their levels are stored
www.DataSheet4inUa.ncoinmternal latch on the low to high transistion of
the Pulse output, and are used for that entire
reset (pin 4)
An active low input that forces both outputs low,
and causes all counter stages to initialize. If
unused, it can be left open circuited (due to the
internal resistor) or preferrably tied to VDD. Refer to
the minimum timing requirements in the Electrical
present. The Schmitt trigger amplifier on the
input simplifies the coupling to slowly varying
signals, while the inherent protection diodes
(shown in the block diagram) allow signals with
peak levels beyond the supply limits to be
connected through a current limiting resistor.
Pulse (pin 6)
This output pin is normally at a low level, but is
momentarily driven high at the beginning of
every timing period. The duration of the pulse is
fixed at 50 cycles of the clock input (nominally 1
second with a 50Hz input). This output will not
assume a high level following a circuit reset until
there has been a valid clock transition.
Out (pin 7)
This is the main timing chain output. It has a
fixed 50% duty cycle, and begins each timing
cycle at a logic low level. Halfway through each
cycle, Out will assume a logic high level and will
remain high until the end of the timing period.
Clock (pin 5)
The counter stages advance on the falling edge
(VDD to VSS) of this input, if there is no reset signal
VSS (pin 8)
Circuit common is connected to this pin. This is
the most negative point in the circuit.
These integrated circuits are available in either the 300 mil plastic DIP format, or in the 200 mil SOIC surface
mount type of package. To order, add the appropriate suffix to the part number:
300 mil Plastic DIP............................... ELM382P
200 mil SOIC..................................... ELM382SM
All rights reserved. Copyright ©2000 Elm Electronics.
Every effort is made to verify the accuracy of information provided in this document, but no representation or warranty can be
given and no liability assumed by Elm Electronics with respect to the accuracy and/or use of any products or information
described in this document. Elm Electronics will not be responsible for any patent infringements arising from the use of these
products or information, and does not authorize or warrant the use of any Elm Electronics product in life support devices and/or
systems. Elm Electronics reserves the right to make changes to the device(s) described in this document in order to improve
reliability, function, or design.
Elm Electronics – Circuits for the Hobbyist
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