Datasheet

TMC4361A Datasheet | Document Revision 1.22 • 2017-JAN-12
123/230
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Read entire documentation; especially the “Supplemental Directives” on page 224.
 MAIN MANUAL 
In certain sections of the velocity ramp it can be useful to boost the current. Boost
current can be assigned temporarily either after ramp start or during the whole
ac-/deceleration phase. All options can be selected separately, or in combination.
i All three options use the same scaling value BOOST_SCALE_VAL .
OPTION 1: BOOST SCALING AT RAMP START
In order to set up and enable boost current scaling within a defined time
frame directly after the velocity ramp start-up, do as follows:
Action:
 Set BOOST_TIME register 0x18 according to the delay period at which boost
current scaling is activated after a velocity ramp start.
 Set BOOST_SCALE_VAL = SCALE _ VALUES (7:0) according to the maximum
current during the boost phase.
 Set boost_current_after_start_en = 1 ( CURRENT_CONF register 0x05).
 Set closed_loop_scale_en = 0 ( CURRENT_CONF register 0x05).
Result:
After the velocity ramp start ( VACTUAL = 0 before), boost scaling is activated
according to BOOST_SCALE_VAL . The boost timer expires after BOOST_TIME clock
cycles. Afterwards, any other selected scaling value is used, if active and selected.
OPTION 2: BOOST SCALING ON ACCELERATION SLOPES
In order to set up and enable boost current scaling for the acceleration
phase of the velocity ramp, do as follows:
Action:
 Set BOOST_SCALE_VAL = SCALE _ VALUES (7:0) according to the maximum
current during the boost phase.
 Set boost_current_on_acc_en = 1 ( CURRENT_CONF register 0x05).
 Set closed_loop_scale_en = 0 ( CURRENT_CONF register 0x05).
Result:
As long as the absolute internal velocity | VACTUAL | increases, the boost scaling
function is activated according to BOOST_SCALE_VAL . The present ramp state can be
read out by the RAMP_STATE flag. Acceleration slopes are indicated by
RAMP_STATE = b’01.
OPTION 3: BOOST SCALING ON DECELERATION SLOPES
In order to set up and enable boost current scaling for the deceleration
phase of the velocity ramp, do as follows:
Action:
 Set BOOST_SCALE_VAL = SCALE _ VALUES (7:0) according to maximum current
during the boost phase.
 Set boost_current_on_dec_en = 1 ( CURRENT_CONF register 0x05).
 Set closed_loop_scale_en = 0 ( CURRENT_CONF register 0x05).
Result:
As long as the absolute internal velocity | VACTUAL | decreases, boost scaling is
activated according to BOOST_SCALE_VAL . The present ramp state can be read out
at the RAMP_STATE flag. Deceleration slopes are indicated by RAMP_STATE = b’10.
Boost Current