Elm Electronics – Circuits for the Hobbyist
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Pin Descriptions
Ordering Information
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............................... ELM339P 200 mil SOIC.....................................ELM339SM
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All rights reserved. Copyright ©1998 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.
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 not required. Refer to
the Electrical Characteristics section for further
information.
Out5 (pin 2)
This output responds to all codes beginning with
the sequence 55. It can be forced to a high level
by issuing 551, to a low level with 550, and to
change state with the sequence 555. It powers up
to a logic low level.
Out7 (pin 3)
Out7 responds to all codes beginning with the
sequence 77. It can be forced to a high level by
issuing 771, to a low level with 770, and to
change state with the sequence 777, if the Pulse7
input is at a low level. If Pulse7 is at a high level,
a 250msec pulse will be output when any of the
three control codes are received.
Pulse7 (pin 4)
This input pin is used to modify the behavior of
Out7, as described above. A logic low level
applied to this pin results in unmodified behavior
of the output, while a logic high forces Out7 to the
pulse mode. Pulse width is nominally 250 msec.
IRRx (pin 5)
The output of a standard 40KHz infrared receiver
module is connected to this pin. The output of
such a module is normally at a high level, and
switches to a logic low when modulated carrier is
received. A series resistor of about 5KΩ must be
connected between this pin and the infrared
module output.
LED (pin 6)
This pin provides a logic high level output when a
valid code is being received by the ELM339. It is
suitable for driving an LED through a current
limiting resistor.
Out3 (pin 7)
This output responds to all codes beginning with
the sequence 33. It can be forced to a high level
by issuing 331, to a low level with 330, and to
change state with the sequence 333. It powers up
to a logic low level.
VSS (pin 8)
Circuit common is connected to this pin. This is
the most negative point in the circuit.
ELM339DSA