ELM313
Pin Descriptions
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.
A (pin 2)
This is the active high output drive signal for the
(first) phase A winding. Normally, this output (and
www.DataSheet4thUe.cDomoutput) would be the first to be energized
when starting a stepping sequence, and is always
the first state entered into internally on powerup.
After powerup, however, the ELM313 treats this
initial state specially, maintaining both A and D
outputs at a low level until the first step command
is received. This in effect keeps the motor off until
selected by control circuitry.
Dir (pin 3)
This pin determines the sequence that the outputs
will be energized in. A high input on the Dir pin
while the step input is pulsed will cause a single
clockwise step, while a low level will cause a
counter-clockwise step. (Refer to Figures 1 & 2).
Dir must be at a stable level prior to the low to
high transition of Step in order to be recognized
(refer to the Tsu specification).
Step (pin 4)
This input is used to control the motion of the
motor. Outputs will change to their next state on
the high to low transition of this input. Step is
normally maintained at a low level, and is only
brought high then low to cause a step to occur.
The Step input is ignored for about 20ms after
power-up to allow sufficient time for external
circuits to stabilize.
D (pin 5)
This is the active high output drive signal for the
(fourth) phase D winding. This pin is treated
specially at powerup - refer to the discussion for
the A output.
C (pin 6)
This is the active high output drive signal for the
(third) phase C winding.
B (pin 7)
This is the active high output drive signal for the
(second) phase B winding.
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............................... ELM313P
200 mil SOIC..................................... ELM313SM
All rights reserved. Copyright ©1999 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.
ELM313DSB
Elm Electronics – Circuits for the Hobbyist
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