STMicroelectronics FlexSPIN: SPI configurable stepper and DC multi motor driver evaluation board EVAL6460 EVAL6460 Data Sheet

Doc ID 17713 Rev 1

35/139

   

   

   

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 

);

–

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.