STSPIN250 EN/FAULT pin problem

[RusikOk]

good afternoon!

I can’t read the FAULT state when the specified load limit is exceeded. the oscilloscope shows that the signal does not drop to a logical zero.

my board

[Cristiana SCARAMEL]

​Hello,

what is the value of pull up resistor connected on EN/FAULT pin?

Moreover, for a better support please share the board schematic.

Regards, Cristiana

[RusikOk]

set different values

R4 - 18k, 36k, 100k

C6 - 10nF, 47nF, 2.2uF

[Cristiana SCARAMEL]

​Please, give more details on the application:

• VS supply voltage value
• Load type
• VREF voltage

Moreover, what do you mean with "specified load limit"?

If you refer to PWM current control and the load current target value, in this case the EN/FAULT open drain pin is not activated.

If instead you are referring to overcurrent protection, keep in mind that the typical value is 4 A.

Could you provide some oscilloscope waveforms when the overcurrent occurs showing:

• the load current
• sense voltage
• EN/FAULT voltage

Regards, Cristiana

[RusikOk]

I do not use PWM.

that is, you want to say that when the current limit is triggered (using WREF and SENSE signals), a FAULT error is not generated?

[Cristiana SCARAMEL]

​The current "limit" set through VREF and SENSE signal is used for PWM current control.

When this peak current is reached a current decay sequence is performed (refer to paragraph 6.3 of STSPIN250 datasheet) and no FAULT signal is generated.

The FAULT pin is forced low when the overcurrent or the short-circuit protection is triggered (see paragraph 6.4).

If you do not use the PWM current control, you should make sure that the maximum sense voltage (Rsense x Iload,max) is always lower than set VREF voltage.

[RusikOk]

thanks!

[Kaan]

Hello,

I had a similar problem with the fault pin. I want to now when the current limiter turned on. Can you recommend a method for that purpose? Thank you.

[Cristiana SCARAMEL]

Hello @Kaan​ and welcome to the ST Community.

The STSPIN250 PWM current controller work on the peak current set trough VREF voltage and the feedback coming from SENSE voltage  (refer to paragraph 6.3 of STSPIN250 datasheet).

The FAULT pin is forced low when the overcurrent or the short-circuit protection is triggered (see paragraph 6.4).

The two features are different.

If need others info please open a new topic with a detailed question.