Datasheet
TMC4361A Datasheet | Document Revision 1.22 • 2017-JAN-12
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Read entire documentation; especially the “Supplemental Directives” on page 224.
MAIN MANUAL
Closed-loop Scaling
In order to save energy, current scaling can be adjusted according to actual load during closed-
loop operation.
Closed-loop scaling slightly alters the use of the scaling register while remaining
consistent in its use of internal scaling and the transmission to the stepper drivers:
1. Closed-loop scaling uses the same scaling register that is also used for
open-loop configuration, as explained in chapter 11, page 120. However, the
specified values that are used – and thus are also named – differently.
2. Internal scaling of MSLUT current values and transfer of these values to the
motor stepper drivers function exactly in the same way as explained in
chapter 10, page 87.
In order to configure and enable closed-loop scaling, do as follows:
Action:
Set proper
CL_IMIN
(
SCALE_VALUES
register 0x06).
Set proper
CL_IMAX
(
SCALE_VALUES
register 0x06).
Set proper
CL_START_UP
(
SCALE_VALUES
register 0x06).
Set
SCALE_VALUES
(31:24) to 0.
Set
closed_loop_scale_en
= 1 (
CURRENT_CONF
register 0x05).
Result:
As soon as closed-loop scaling is enabled, all other open-loop scaling options are
automatically disabled. The following scaling situations are possible:
1. In case |
ENC_POS_DEV
| ≤
CL_START_UP
, current values are scaled with
CL_IMIN
.
2. In case |
ENC_POS_DEV
| >
CL_START_UP
and |
ENC_POS_DEV
| ≤
CL_BETA,
current values are scaled with a factor that increases linearly from
CL_IMIN
to
CL_IMAX
.
3. In case |
ENC_POS_DEV
| >
CL_BETA
, current values are scaled with
CL_IMAX
.
The chart below identifies the actual scaling parameter SCALE_PARAM, which is
dependent on the above described situations:
Turn page for information about adaptations on the scaling transformation process
during closed-loop operation.
Closed-Loop
Scaling
Configuration
and Enabling
Figure 67: Closed-Loop Current Scaling
SCALE_PARAM
0°
CL_IMIN
XACTUAL
–CL_BETA CL_BETA
CL_IMAX
ENC_POS_DEV
[µSteps]
128
(45°)
256
(90°)
384
(135°)
-128
(-45°)
-256
(-90°)
-384
(-135°)
–CL_START_UP CL_START_UP