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RusikOk
RusikOk
Associate II
February 11, 2020
Solved

STSPIN250 EN/FAULT pin problem

  • February 11, 2020
  • 5 replies
  • 3621 views

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.

0690X00000D9RuBQAV.bmp

my board

0690X00000D9S0dQAF.jpg0690X00000D9RzpQAF.jpg

This topic has been closed for replies.
Best answer by 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.

5 replies

Cristiana SCARAMEL
Cristiana SCARAMEL
ST Employee
February 13, 2020

​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

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RusikOk
RusikOkAuthor
Associate II
February 13, 2020

set different values

R4 - 18k, 36k, 100k

C6 - 10nF, 47nF, 2.2uF

0690X00000DA2rTQAT.png

Cristiana SCARAMEL
Cristiana SCARAMEL
ST Employee
February 13, 2020

​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

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RusikOk
RusikOkAuthor
Associate II
February 13, 2020

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
Cristiana SCARAMELBest answer
ST Employee
February 13, 2020

​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.

"If you feel a post has answered your question, please click ""Accept as Solution"""
RusikOk
RusikOkAuthor
Associate II
February 14, 2020

thanks!

Kaan
Kaan
Visitor II
April 20, 2021

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
Cristiana SCARAMEL
ST Employee
April 20, 2021

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.

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