L6460 datasheet(35/139 Pages) STMICROELECTRONICS

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L6460

Supervisory system

Doc ID 17713 Rev 1

35/139

5.3

Thermal shut down generation circuit

The third component of the supervisory circuit is the thermal shut down generation circuit.

This circuit generates two different flags depending on the IC temperature:

–

the “TSD” flag indicates that the IC temperature is greater than the maximum

allowable temperature.

–

the “Warm” flag, that can be read using serial interface, becomes active at a lower

temperature respect to TSD signal, therefore it can be used to prevent the IC from

reaching over temperature.

When a TSD event occurs, L6460 will enter in the reset state placing the bridges in high

impedance and turning off all regulators and other circuits until the internal temperature

decreases below the Warm temperature. At this point, L6460 will restart the power up

sequence and TSD bit will be set and will be readable as soon as L6460 will come out from

the reset state.

This TSD bit can be reset in three ways:

–

by writing a logic level ‘1’ in the ClearTSD bit in the ICTemp register (see

Chapter 24);

–

by a POR event;

–

by entering in “Low Power Mode”.

The Warm bit, set by L6460 when IC is working over the warming temperature, can be read

using the SPI interface. Once this bit is set it can be reset in three ways:

–

by writing a logic level ‘1’ in the ClearWarm bit;

–

by a POR event;

–

by entering in “Low Power Mode”.

The thermal sensor voltage can be converted using the internal A/D: this way the

microcontroller can directly measure the IC temperature.

To avoid unwanted commutation especially when temperature is near the thresholds, the

output signal is filtered for both TSD and Warm.

L6460 데이터시트(PDF) 35 Page - STMicroelectronics