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
During standstill, the current can be scaled down considerably in most applications
because the energy demand is lower than during motion. In addition to the scaling
value, the standby delay must be configured. The delay defines the time between
ramp stop and startup of hold scaling. Whenever the delay is set
to 0, hold scaling is immediately enabled at the end of the velocity ramp. Because
most applications require waiting for system oscillations after ramp stop, this delay
must be set up in most cases.
In order to set up and enable hold current scaling, do as follows:
Action:
Set the time frame for STDBY_DEALY register 0x15 after ramp stop, and before
standby phase starts.
Set
HOLD_SCALE_VAL
=
SCALE
_
VALUES
(31:24) according to the maximum
current during motor standstill.
Set
hold_current_scale_en
= 1 (
CURRENT_CONF
register 0x05).
Set
closed_loop_scale_en
= 0 (
CURRENT_CONF
register 0x05).
Result:
The standby timer is started as soon as
VACTUAL
reaches 0. After
STDBY
_
DELAY
clock
cycles the standby timer expires that activates the hold scaling phase.
The standby status can be forwarded via STDBY_CLK output pin.
In order to generate an output standby signal, do as follows:
Action:
Set
stdby_clk_pin_assignment
(1) = 0 (Bit14 of
GENERAL_CONF
register 0x00).
Set
stdby_clk_pin_assignment
(0) (Bit13 of
GENERAL_CONF
register 0x00)
according to the active voltage level of the output pin.
Result:
STDBY_CLK output pin forwards the internally generated standby status. The active
output level equals
stdby_clk_pin_assignment
(0).
Some applications require a freewheeling behavior after ramp stop. This means that
the current values are set to 0. A delay timer can be configured to define the time
between standby start and the beginning of freewheeling.
In order to set up and enable freewheeling, do as follows:
Action:
Set
FREEWHEEL_DELAY
register 0x16 according to the duration of the time after
standby start, so that freewheeling is activated accordingly.
Set
freewheeling_en
= 1 (
CURRENT_CONF
register 0x05).
Set
closed_loop_scale_en
= 0 (
CURRENT_CONF
register 0x05).
Result:
The freewheeling timer is started as soon as the standby mode is activated. After
completion of
FREEWHEEL_DELAY
clock cycles, the freewheeling timer expires that
activates the freewheeling phase.
i Just before the velocity ramps starts internal scaling is set to the standby scaling
value. This avoids starting the ramp at current values that are equal to 0.
Hold Current
Scaling
Standby Status
Freewheeling