SPSB081 datasheet(39/137 Pages) STMICROELECTRONICS

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3.20

Temperature warning and shutdown

If any of the cluster junction temperatures rises above the temperature warning threshold (TW ON), a temperature

warning flag is set after the temperature warning filter time (tFTJTW) and can be read via SPI. If the junction

temperature increases above the temperature shutdown threshold (TSD1 OFF), the thermal shutdown bit is set

and the power transistors of all output stages are switched off to protect the device after the thermal shutdown

filter time. The temperature warning and thermal shutdown flags are latched and must be cleared by the

microcontroller. This is done by a read and clear command on the relevant status register (TSD1 is bit 4 in

status register 1 while TW is bit 8 in status register 2).

After these bits have been cleared, the output stages are reactivated. If the temperature is still above the thermal

warning threshold, the thermal warning bit is set after tFTJTW. Once this bit is set and the temperature is above the

temperature shutdown threshold, temperature shutdown is detected after tFTJTW and the outputs are switched off.

Therefore, the minimum time after which the outputs are switched off after the bits have been cleared in case the

temperature is still above the thermo shutdown threshold is twice the thermo warning/shutdown filter time tFTJTW.

3.21

Thermal clusters

To provide an advanced on-chip temperature control, the power outputs are grouped in four clusters with

dedicated thermal sensors. The sensors are suitably located on the device. In case the temperature of a cluster

reaches the thermal shutdown threshold, the outputs assigned to this cluster are shut down (all other outputs

remain active). Each output cluster has a dedicated temperature warning and shutdown flag (SR7 and SR8).

Hence, the thermal cluster concept identifies a group of outputs in which one or more channels are in overload

condition.

If thermal shutdown has occurred within an output cluster, or if temperature is rising within a cluster, it may be

desired to identify which of the output(s) is (are) determining the temperature increase.

Thermal clusters can be configured using bit TSD_CLUSTER_EN (CR20):

•

Standard mode (default): as soon as any cluster reaches thermal threshold the device is switched off. V1

regulator remains on and is switched off reaching TSD2. All the thermal sensors are put in “OR”.

In fact, if one of these sensors reaches TSD1:

–

All outputs drivers and V2 are turned OFF.

–

V1 remains on until TSD2.

–

LIN and CAN transmitter are turned OFF (but they are forced in "receive only" mode).

•

Cluster mode: only the cluster, which reached shutdown temperature is switched off.

In case cluster Th_CL1 reaches TSD1:

–

V1 remains ON until TSD2

In case cluster Th_CL4 reaches TSD1.

–

All outputs drivers and V2 are turned OFF.

–

V1 remains on until TSD2.

–

LIN and CAN transmitter are turned OFF (but they are forced in "receive only" mode).

SPSB081

Temperature warning and shutdown

DS14048 - Rev 3

page 39/137

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