Datasheet

TMC262 / TMC262C DATASHEET (Rev. 2.22 / 2019-FEB-22) 45
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11.3 Temperature Sensors
The TMC262 integrates a two-level temperature sensor (100°C warning and 150°C shutdown) for
diagnostics and for protection of the power MOSFETs. The temperature detector can be triggered by
heat accumulation on the board, for example due to missing convection cooling. Most critical
situations, in which the MOSFETs could be overheated, are avoided when using the short protection.
For most applications, the overtemperature warning indicates an abnormal operation situation and
can be used to trigger an alarm or power-reduction measures. If continuous operation in hot
environments is necessary, a more precise mechanism based on temperature measurement should be
used. The thermal shutdown is strictly an emergency measure and temperature rising to the
shutdown level should be prevented by design. The shutdown temperature is above the specified
operating temperature range of the chip.
Hint for TMC262C, only
After triggering the overtemperature sensor (ot flag), the driver remains switched off until the system
temperature falls below the overtemperature release level (120°C) to avoid continuous heating to the
shutdown level. Cool down typically needs a few 100ms to 1 second.
The high-side P-channel gate drivers have a temperature dependency which can be compensated to
some extent by increasing the gate driver current when the warning temperature threshold is
reached. The chip automatically corrects for the temperature dependency above the warning
temperature when the temperature-compensated modes of SLPH is used. In these modes, the gate
driver current is increased by one step when the temperature warning threshold is reached.
11.4 Undervoltage Detection
The undervoltage detector monitors both the internal logic supply voltage and the supply voltage. It
prevents operation of the chip when the MOSFETs cannot be guaranteed to operate properly because
the gate drive voltage is too low. It also initializes the chip at power up.
In undervoltage conditions, the logic control block becomes reset and the driver is disabled. All
MOSFETs are switched off. All internal registers are reset to zero. Software also should monitor the
supply voltage to detect an undervoltage condition. If software cannot measure the supply voltage,
an undervoltage condition can be detected when the response to an SPI command returns only zero
bits in the response and no bits are shifted through the internal shift register from SDI to SDO. After
a reset due to undervoltage occurs, the CS parameter is cleared, which is reflected in an SE status of 0
in the read response.
Status
Description
Range
Comment
OTPW
Overtemperature warning. This bit indicates
whether the warning threshold is reached.
Software can react to this setting by reducing
current.
0 / 1
1: temperature
prewarning level
reached
OT
Overtemperature shutdown. This bit indicates
whether the shutdown threshold has been
reached and the driver has been disabled.
0 / 1
1: driver shut down
due to over-
temperature
OTSENS
(TMC262C only)
Program overtemperature threshold to a reduced
level in order to give better protection for the
external power stage and other components. The
driver re-enables when the temperature falls
below 120°C.
0 / 1
0: 150°C
1: 136°C