ELM415
Pin Descriptions
VDD (pin 1)
Invert (pin 4)
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.
This input controls the quiescent level at pin 3 (the
Count output). If low, the level at pin 3 will also
normally be low, pulsing momentarily to a high level
when a button is pressed. Setting this pin high
causes pin 3 to rest at a high level, with the output
pulses momentarily going low.
Up/Down (pin 2)
Repeat (pin 5)
This is the count direction output, which changes
state depending on which pushbutton is being
pressed. If it is the Up pushbutton, this output will be
at a high level, while a Down results in it being at a
low level. The output remains at a level until the
alternate pushbutton is pressed. When it does
change, it does so approximately 1 msec prior to an
active pulse appearing on Count.
This input controls the circuit response should one of
the pushbuttons be continuously pressed. If this pin
is at a low level, there will only be a single Count
output generated, no matter how long the button
stays pressed. If this pin is at a high level, a single
pulse is output, then after a short delay, a continuous
stream of pulses are generated for as long as the
button is held.
Count (pin 3)
UpSw (pin 6) and DownSw (pin 7)
This output provides a pulsing signal in response to
one of the two pushbuttons being pressed.
Simultaneous pressing of both switches is detected
and results in no output. The width of the output
pulse is fixed at approximately 1 msec, but the
polarity can be changed depending on the level at
the Invert input. This output is used to ‘clock’ the
controlled counter circuit.
The pushbuttons are connected to these pins.
Internal pullup resistors are provided to bias the
input when no button is pressed, simplifying the
circuitry required. These are standard CMOS inputs,
so the use of external delay components (capacitors,
etc.) is not recommended.
VSS (pin 8)
Circuit common is connected to this pin. This is the
most negative point in the circuit.
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............................... ELM415P
200 mil SOIC..................................... ELM415SM
All rights reserved. Copyright ©2002 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.
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ELM415DSA
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