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 
Current Scaling Examples
In this example, the following scale options are enabled:
 Standby scaling
 Freewheeling
 Boost scaling at start
 Boost scaling on deceleration ramps
 Drive scaling
The different scaling stages of the trapezoidal velocity ramp are shown in different
colors in the Figure A below.
Figure B shows the internal scale parameter SCALE_PARAM as function of time. The
scale parameter is not switched immediately whenever the scaling situations alters;
because delay timers are used. A transition time between the assigned values is
generated. Four transition phases are shown that are calculated as follows:
t
START_SCALE
= ( BOOST_SCALE_VAL – HOLD_SCALE_VAL ) · UP_SCALE_DELAY ·
f
CLK
t
DN_SCALE
= ( BOOST_SCALE_VAL – DRV1_SCALE_VAL ) ·
DRV_SCALE_DELAY · f
CLK
t
UP_SCALE
= ( BOOST_SCALE_VAL – DRV1_SCALE_VAL ) · UP_SCALE_DELAY ·
f
CLK
t
HOLD_SCALE
= ( DRV1_SCALE_VAL – HOLD_SCALE_VAL ) · HOLD_SCALE_DELAY ·
f
CLK
Figure C shows the different timers that are used:
 To finish boost scaling after start.
 To start standby scaling.
 To start freewheeling.
i These three delay values are directly determined by their respective register
values 0x1B, 0x15, and 0x16.
Figure 55: Scaling Example 1
v(t)
t
t
SCALE_PARAM
Boost scaling
Drv1 scaling
StdBy scaling
Freewheeling
t
scale timer [clk cycles]
BOOST_SCALE_VAL
DRV1_SCALE_VAL
HOLD_SCALE_VAL
STDBY_DELAY
FREEWHEEL_DELAY
BOOST_TIME
t
DN_SCALE
t
UP_SCALE
t
DN_SCALE
t
HOLD_SCALE
t
START_SCALE
A)
B)
C)
Scaling Mode
Example 1