L99DZ320 datasheet(77/146 Pages) STMICROELECTRONICS

77 / 146 page

3.30

Temperature warning and shutdown

If any of the cluster (see Section 3.31: Digital thermal clusters) junction temperatures rise above the temperature

warning threshold (TjTW), 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 (TjTS), 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 gates of the H-bridge are discharged by the ‘resistive low’ mode. 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 an arbitrary register, because both bits are part of the global status

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 still above

the 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 in this case, is twice the thermo warning/

thermo shutdown filter time tfTjTW.

3.31

Digital thermal clusters

In order to provide an advanced on chip temperature control, the power outputs are grouped in eight clusters with

dedicated thermal sensors. The sensors are suitably located on the device (see Figure 39. Digital thermal clusters

identification). In case the temperature of an output cluster reaches the thermal shutdown threshold, the outputs

assigned to this cluster are shutdown (all other outputs remain active). Each output cluster has a dedicated

temperature warning and shutdown flag (SR1 and SR2). Hence, the thermal cluster concept allows to identify a

group of outputs in which one or more channels are in the overload condition.

Thermal clusters can be configured using the bit TSD_CLUSTER_EN (CR3):

•

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

regulator remains on and it 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, charge-pump and V2 are turned OFF

–

V1 remains on until TSD2

–

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

•

Cluster mode: only the cluster that reaches shutdown temperature is switched off.

In case cluster Th_CL7 reaches TSD1:

–

HS0, HS15, V2 are turned OFF

–

V1 remains ON until TSD2

In case cluster Th_CL8 reaches TSD1:

–

all outputs drivers, charge pump and V2 are turned OFF

–

V1 remains on until TSD2

–

LIN and CAN transmitters are turned OFF (they are forced in "receive only" mode)

L99DZ320

Functional description

DS14235 - Rev 5

page 77/146

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