L9374LF datasheet(43/80 Pages) STMICROELECTRONICS

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L9374LF

Circuit description

Outputs Q1 and Q2 have a selectable overcurrent threshold. These currents are individually

selectable as well. (see Table 15 also 5.1.8: Configuration register 2 - current control / over-

voltage threshold (address 14))

This failure detection is also used during SVDT (see 4.8.13: Silent valve driver test (SVDT)).

4.8.4

Thermal warning and thermal shutdown

The L9374LF is equipped with a two stage thermal protection system. This system provides

for an early thermal warning and a thermal overload shutdown protection. With thermal

warning some countermeasures can be realized by the Master

C to potentially prevent

thermal shutdown. The temperature for each output is only measured when the output is on.

Temperature warning has the same functionality as over-temperature. The only differences

are:



The threshold is 20°C below over-temperature.



The Output is not shut down.



The SPI-Bit shows the actual status at the time it is accessed.

Thermal warning

If the measured value is higher than the thermal warning threshold, TW (Table 15), for tTW

(Table 18)the appropriate thermal warning bit for that output is set in the SPI Status register

(bit D8 of status registers 1 - 4, Section 5.2.2). No other action is taken. Reading the status

registers clears the TW bit(s) once the device is cooled sufficiently. This failure detection is

used for all outputs.

Thermal shutdown

When the measured temperature exceeds the thermal shutdown threshold, TSD, a failure is

detected. This failure detection is filtered for tOT (40 μs typ., Table 18). After tOT the output is

shut down immediately and all of the set point and control variables are set to zero. This

disables the output from further actuation until the over temperature condition is removed

and appropriate status register(s) (status registers 1 - 4, Section 5.2.2)) are read. Reading

the status registers clears the TSD bits once the device is cooled sufficiently. This failure

detection is used for all outputs.

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