ELM339

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.

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 5K

Ω 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.

Circuit common is connected to this pin. This is

the most negative point in the circuit.

ELM339DSA