Datasheet

TMC262 / TMC262C DATASHEET (Rev. 2.22 / 2019-FEB-22) 44
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The short detector is controlled by a mode bit and a parameter:
Mode bit /
Parameter
Description
Setting
Comment
DISS2G
Short to ground detection disable bit.
0/1
0: Short to ground
detection enabled
1: Short to ground
detection disabled
TS2G
This setting controls the short detection delay
time. It needs to cover the switching slope time.
A higher setting reduces sensitivity to capacitive
loads.
0… 3
%00: 3.2µs.
%01: 1.6µs.
%10: 1.2µs.
%11: 0.8µs.
EN_S2VS
(TMC262C, only)
Explicitly enable short to VS and overcurrent
protection by setting this bit.
0/1
Enable detection for
normal use (1).
SHRTSENS
(TMC262C, only)
The high-side overcurrent detector can be set to
a higher sensitivity by setting this flag. This will
allow detection of wrong cabling even with
higher resistive motors.
0/1
0: Low sensitivity
1: High sensitivity
Hint
Once a short condition is safely detected, the corresponding driver bridge (A or B) becomes switched
off, and the s2ga or s2gb flag becomes set.
To restart the motor, disable and re-enable the driver.
Attention
Short protection cannot protect the system and the power stages for all possible short events, as a
short event is rather undefined and a complex network of external components may be involved.
Therefore, short circuits should basically be avoided.
11.2 Open-Load Detection
Interrupted cables are a common cause for systems failing, e.g. when connectors are not firmly
plugged. The TMC2590 detects open load conditions by checking, if it can reach the desired motor coil
current. This way, also undervoltage conditions, high motor velocity settings or short and
overtemperature conditions may cause triggering of the open load flag, and inform the user, that
motor torque may suffer. In motor stand still, open load cannot be measured, as the coils might
eventually have zero current.
Hint
Open load detection is provided for system debugging. Open load detection does not necessarily
indicate a malfunction of the driver.
In order to safely detect an interrupted coil connection, read out the open load flags at low or
nominal motor velocity operation, only. However, the ola and olb flags have just informative
character and do not cause any action of the driver. False indication may result with full- or halfstep
operation. Use microstepping for a safe result.
The open-load detection status is indicated by two bits:
Status flag
Description
Range
Comment
OLA
These bits indicate an open-load condition on
coil A and coil B. The flags become set, if no
chopper event has happened during the last
period with constant coil polarity. The flag is not
updated with too low actual coil current below
1/16 of maximum setting. It is a pure indicator.
No action is taken depending on these flags.
0 / 1
0: No open-load
detected
1: Open-load
detected
OLB