AMIS-30621 Datasheet, PDF (13/59 Pages) AMI SEMICONDUCTOR – LIN Microstepping Motordriver

AMIS−30621
Position Ranges
A position is coded by using the binary two’s complement format. According to the positioning commands used and to the
chosen stepping mode, the position range will be as shown in the following table.
Table 11. POSITION RANGE
Command
Stepping Mode
SetPosition
Half−stepping
1/4^th micro−stepping
1/8^th micro−stepping
1/16^th micro−stepping
SetPositionShort
Half−stepping
Position Range
−4096 to +4095
−8192 to +8191
−16384 to +16383
−32768 to +32767
−1024 to +1023
Full Range Excursion
8192 half−steps
16384 micro−steps
32768 micro−steps
65536 micro−steps
2048 half−steps
Number of Bits
13
14
15
16
11
When using the command SetPosition, although
coded on 16 bits, the position word will have to be shifted to
the left by a certain number of bits, according to the stepping
mode.
Secure Position
A secure position can be programmed. It is coded in
11−bits, thus having a lower resolution than normal
positions, as shown in the following table. See also
command GotoSecurePosition and LIN lost
behavior.
Table 12. SECURE POSITION
Stepping Mode
Secure Position Resolution
Half−stepping
1/4^th micro−stepping
1/8^th micro−stepping
1/16^th micro−stepping
4 half−steps
8 micro−steps (1/4^th)
16 micro−steps (1/8^th)
32 micro−steps (1/16^th)
Important
NOTES: The secure position is disabled in case the programmed value is the reserved code “10000000000” (0x400 or most negative
position).
At start up the OTP register is copied in RAM as illustrated below.
SecPos10
SecPos9
SecPos8
SecPos2
SecPos1
SecPos0
RAM
SecPos10
SecPos9
SecPos8
SecPos2
SecPos1
SecPos0
OTP
Shaft
A shaft bit, which can be programmed in OTP or with
command SetMotorParam, defines whether a positive
motion is a clockwise (CW) or counter−clockwise rotation
(CCW) (an outer or an inner motion for linear actuators):
• Shaft = 0 ⇒ MOTXP is used as positive pin of the X
coil, while MOTXN is the negative one.
• Shaft = 1 ⇒ opposite situation.
STRUCTURAL DESCRIPTION
See also the Block Diagram in Figure 1.
Stepper Motordriver
The Motor driver receives the control signals from the
control logic. The main features are:
• Two H−bridges, designed to drive a stepper motor with
two separated coils. Each coil (X and Y) is driven by
one H−bridge, and the driver controls the currents
flowing through the coils. The rotational position of the
rotor, in unloaded condition, is defined by the ratio of
current flowing in X and Y. The torque of the stepper
motor when unloaded is controlled by the magnitude of
the currents in X and Y.
• The control block for the H−bridges, including the
PWM control, the synchronous rectification and the
internal current sensing circuitry.
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