STSPIN958 Thermal shutdown does not work

[amin.kamal]

Hi,

We are using STSPIN958 for BLDC control, and under 33V, 2A, when external force applies to servo, and the current goes up to about 2A, the chip burns before the thermal shut down kicks in.

I would also like to know the value of "Tsd" delay timing parameter in thermal shutdown sequence: Figure 16 of page 21/34 of its datasheet. This value is not published.

Thanks,

Amin

[Cristiana SCARAMEL]

Hello @amin.kamal  and welcome to the ST Community.

For a better support, could you share more details about your application?
- What configuration is the STSPIN958 working in?
- What kind of control are you applying?
- How are you measuring the motor current?

I suggest to monitor the LSSx and OUTx pins to check if any voltage overshoot occurs on these pins.

Concerning the intervention time of the thermal shutdown protection, it is few tens of microseconds.

[amin.kamal]

It is BLDC application.

Two STSPIN958 chips are being set in Dual Half Bridge PWM Trimming mode, and 3 lines of motor outputs are connected to BLDC.

A PID position control is applied from the servo encoder to the PWM voltage.

We are measuring the current using Current Probes on motor lines, and Power Supply Current Reading.

We are still investigating this. Rosario from ST also provided some more information about the current ratings at different configurations, and apparently, the Current Spec of the chip is about 1.7A in the "Dual Half Bridge" mode, which is the mode we are using. We probably overloaded the chip by 2 AMPs, and that is why it quickly burned.