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IM483 Operating Instructions Revision R032306
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IM483 Operating Instructions Revision R032306
S e c t i o n 4
T h e o r y o f O p e r a t i o n
S e c t i o n O v e r v i e w
This section will cover the circuit operation for the IM483 microstepping
driver.
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Circuit Operation.
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Microstep Select Inputs.
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Stepping.
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Dual PWM Circuit.
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Fullstep Output.
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Timing.
C i r c u i t O p e r a t i o n
Microstepping drives have a much higher degree of suitability for ap-
plications that require smooth operation and accurate positioning at low
speeds than do half/fullstep drivers and reduction gearing. The IM483,
which can to be set to microstep resolutions as high as 51,200 microsteps/
rev (256 microsteps/step) using a 1.8° stepping motor, is ideal for such
applications.
In order to subdivide motor steps into microsteps while maintaining
positional accuracy, precise current control is required. The IM483 ac-
complishes this by the use of a unique Dual PWM circuit built into the
patented IM2000 Microstep Controller ASIC, which resides at the heart of
the IM483. This PWM circuit uses alternating recirculating/non-recircu-
lating modes to accurately regulate the current in the windings of a two
phase stepping motor.
Figure 4.1: IM483 Block Diagram
INPUT
LOGIC
INPUT
LOGIC
ISOLATION
CIRCUITRY
SINE/COSINE
POSITION
GENERATOR
MICROSTEP
RESOLUTION
SELECTION
STEP CLOCK
DIRECTION
ENABLE
RESET
CURRENT
CONTROL
USER
INTERFACE
POWER
SUPPLY
OPTO
SUPPLY
20kHz CHOP.
OSC
PROTECTION
CIRCUIT
IM2000 MICROSTEP
CONTROLLER
IM483 MICROSTEPPING DRIVER
PHASE A/B
OUTPUT
CIRCUITRY
CURRENT
SENSING
STEPPING
MOTOR
SHORT
CIRCUIT
PROTECTION
OVER CURRENT
PROTECTION
