Theory Of Operation; Section Overview; Circuit Operation; Figure 4.1 Im805 Block Diagram - Intelligent Motion Systems IM805 Operating Instructions Manual

S e c t i o n 4
S e c t i o n O v e r v i e w
This section will cover the circuit operation for the IM805 microstepping
driver.
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 IM805,
which can 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 appli-
cations.
In order to subdivide motor steps into microsteps while maintaining
positional accuracy, precise current control is required. The IM805 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 IM805. This PWM circuit uses alternating recirculating/non-recircu-
lating modes to accurately regulate the current in the windings of a two
phase stepping motor.
USER
INTERFACE
STEP CLOCK
DIRECTION
ENABLE
RESET

Circuit Operation.

n
n Microstep Select Inputs.
n Stepping.
n Dual PWM Circuit.
Fullstep Output.
n
Timing.
n
OPTO
SUPPLY
INPUT
LOGIC
ISOLATION
INPUT
CIRCUITRY
LOGIC
IM2000 MICROSTEP
CONTROLLER
IM805 MICROSTEPPING DRIVER
Figure 4.1: IM805 Block Diagram
T h e o r y o f O p e r a t i o n
20kHz CHOP.
OSC
MICROSTEP
RESOLUTION
SELECTION
CURRENT
CONTROL
SINE/COSINE
POSITION
GENERATOR
PROTECTION
CIRCUIT
IM805 Operating Instructions Revision R032306
POWER
SUPPLY
SHORT
CIRCUIT
PROTECTION
PHASE A/B
OUTPUT
CIRCUITRY
CURRENT
STEPPING
SENSING
MOTOR
OVER CURRENT
PROTECTION
15