AMIS30623C623BRG Datasheet, PDF (14/61 Pages) ON Semiconductor – Micro-stepping Motor Driver

AMIS−30623
• The charge pump to allow driving of the H−bridges’
high side transistors.
• Two pre−scale 4−bit DAC’s to set the maximum
magnitude of the current through X and Y.
• Two DAC’s to set the correct current ratio through X
and Y.
Battery voltage monitoring is also performed by this
block, which provides the required information to the
control logic part. The same applies for detection and
reporting of an electrical problem that could occur on the
coils or the charge pump.
Control Logic (Position Controller and Main Control)
The control logic block stores the information provided by
the LIN interface (in a RAM or an OTP memory) and
digitally controls the positioning of the stepper motor in
terms of speed and acceleration, by feeding the right signals
to the motordriver state machine.
It will take into account the successive positioning
commands to properly initiate or stop the stepper motor in
order to reach the set point in a minimum time.
It also receives feedback from the motordriver part in
order to manage possible problems and decide on internal
actions and reporting to the LIN interface.
Motion Detection
Motion detection is based on the back−emf generated
internally in the running motor. When the motor is blocked,
e.g. when it hits the end position, the velocity, and as a result
also the generated back−emf, is disturbed. The
AMIS−30623 senses the back−emf, calculates a moving
average and compares the value with two independent
threshold levels. If the back−emf disturbance is bigger than
the set threshold, the running motor is stopped.
LIN Interface
The LIN interface implements the physical layer and the
MAC and LLC layers according to the OSI reference model.
It provides and gets information to and from the control logic
block, in order to drive the stepper motor, to configure the
way this motor must be driven, or to get information such as
actual position or diagnosis (temperature, battery voltage,
electrical status...) and pass it to the LIN master node.
Miscellaneous
The AMIS−30623 also contains the following:
• An internal oscillator, needed for the LIN protocol
handler as well as the control logic and the PWM
control of the motordriver.
• An internal trimmed voltage source for precise
referencing.
• A protection block featuring a thermal shutdown and a
power−on−reset circuit.
• A 5 V regulator (from the battery supply) to supply the
internal logic circuitry.
FUNCTIONS DESCRIPTION
This chapter describes the following functional blocks in Position Controller
more detail:
• Position controller
• Main control and register, OTP memory + ROM
• Motordriver
Positioning and Motion Control
A positioning command will produce a motion as
illustrated in Figure 7. A motion starts with an acceleration
phase from minimum velocity (Vmin) to maximum velocity
The Motion detection and LIN controller are discussed in _{(Vmax) and ends with a symmetrical deceleration. This is}
separate chapters.
defined by the control logic according to the position
required by the application and the parameters programmed
by the application during the configuration phase. The
Acceleration
Ì _range
ÌÌ _{Zero Speed}
Hold Current
ÌÌÌÌ _Pstart
ÌÌÌ_Pmin
current in the coils is also programmable.
Velocity
Vmax
Vmin
P=0
Deceleration
ÌÌ _range
ÌÌÌÌ_{Zero Speed}
Hold Current
ÌÌÌÌÌÌÌÌÌÌ _Pstop
Position
ÌÌÌÌ_Pmax
Figure 7. Positioning and Motion Control
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