Datasheet

TMC2209 DATASHEET (Rev. 1.03 / 2019-JUN-26) 65
www.trinamic.com
15 Driver Diagnostic Flags
The TMC2209 drivers supply a complete set of diagnostic and protection capabilities, like short to GND
protection, short to VS protection and undervoltage detection. A detection of an open load condition
allows testing if a motor coil connection is interrupted. See the DRV_STATUS table for details.
15.1 Temperature Measurement
The driver integrates a four-level temperature sensor (pre-warning and thermal shutdown) for
diagnostics and for protection of the IC against excess heat. The thresholds can be adapted by UART
or OTP programming. Heat is mainly generated by the motor driver stages, and, at increased voltage,
by the internal voltage regulator. Most critical situations, where the driver MOSFETs could be
overheated, are avoided by the short to GND protection. For many applications, the overtemperature
pre-warning will indicate an abnormal operation situation and can be used to initiate user warning or
power reduction measures like motor current reduction. The thermal shutdown is just an emergency
measure and temperature rising to the shutdown level should be prevented by design.
TEMPERATURE THRESHOLDS
Overtemperature
Setting
Comment
143°C
(OTPW: 120°C)
Default setting. This setting is safest to switch off the driver stage before the IC
can be destroyed by overheating. On a large PCB, the power MOSFETs reach
roughly 150°C peak temperature when the temperature detector is triggered with
this setting. This is a trip typical point for overtemperature shut down. The
overtemperature pre-warning threshold of 120°C gives lots of headroom to react
to high driver temperature, e.g. by reducing motor current.
150°C
(OTPW:
120°C or 143°C)
Optional setting (OTP or UART). For small PCBs with high thermal resistance
between PCB and environment, this setting provides some additional headroom.
The small PCB shows less temperature difference between the MOSFETs and the
sensor.
157°C
(OTPW: 143°C)
Optional setting (UART). For applications, where a stop of the motor cannot be
tolerated, this setting provides highest headroom, e.g. at high environment
temperature ratings. Using the 143°C overtemperature pre-warning to reduce
motor current ensures that the motor is not switched off by the thermal
threshold.
Attention
Overtemperature protection cannot in all cases avoid thermal destruction of the IC. In case the rated
motor current is exceed, e.g. by operating a motor in StealthChop with wrong parameters, or with
automatic tuning parameters not fitting the operating conditions, excess heat generation can quickly
heat up the driver before the overtemperature sensor can react. This is due to a delay in heat
conduction over the IC die.
After triggering the overtemperature sensor (ot flag), the driver remains switched off until the system
temperature falls below the pre-warning level (otpw) to avoid continuous heating to the shutdown
level.
15.2 Short Protection
The TMC2209 power stages are protected against a short circuit condition by an additional measure-
ment of the current flowing through each of the power stage MOSFETs. This is important, as most
short circuit conditions result from a motor cable insulation defect, e.g. when touching the conducting
parts connected to the system ground. The short detection is protected against spurious triggering,
e.g. by ESD discharges, by retrying three times before switching off the motor.