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bfa001
Associate II
May 7, 2026
Solved

STMC Board Designer 1.2.2 Over current STSPIN32G4 internal op-amp graphical representation is erroneous

  • May 7, 2026
  • 2 replies
  • 188 views

The graphical representation shows an internal op-amp amplifying the signal entering the comparator's positive input.

However, the STSPIN32G4 positive input comparator cannot be an op-amp output unfortunately and is limited to op-amp positive inputs - see Ref. Manual RM0440 ver 9 (Figure 168).

This is misleading, because only non-amplified signals gets to the positive input of the comparator.

 

 

 

Best answer by bfa001

The Motor Control Workbench User's Manual is correct with the proper graphical representation.

STM32 Motor Control SDK: Current sensing and protection using embedded OpAmps and Comparators

bfa001_0-1778657300020.png

bfa001_1-1778657331977.png

Importantly, the op-amp output cannot be used for over-current sensing because during power up and reset they are not operational. As a result, if using an op-amp output and there is a short happening during power-up or reset, the over-current protection will be disabled during those transient times.

bfa001

 

 

2 replies

GMA
GMA
Technical Moderator
May 11, 2026

Hello @bfa001,

In Board Designer overcurrent protection internal comparator OCP mode, the MCU is limited to the area indicated by the red square. In the description, OPAMP refers to the external gain value and does not indicate the use of an internal OpAmp Ip.

image.png

If you agree with the answer, please accept it by clicking on 'Accept as solution'.Best regards.GMA
B
bfa001Author
Associate II
May 12, 2026

Hello ,

The graphical representation is misleading - the selection of the internal op-amp must follow the correct representation with the positive input connected to the outside pin selected.

To say that only a part of this graphical representation is valid is ludicrous - when the output of an op-amp is connected graphically.

This is so confusing for the person who start a custom board design and may lead to incorrect choices.

Kind regards,

bfa001

 

 

 

B
bfa001AuthorAnswer
Associate II
May 13, 2026

The Motor Control Workbench User's Manual is correct with the proper graphical representation.

STM32 Motor Control SDK: Current sensing and protection using embedded OpAmps and Comparators

bfa001_0-1778657300020.png

bfa001_1-1778657331977.png

Importantly, the op-amp output cannot be used for over-current sensing because during power up and reset they are not operational. As a result, if using an op-amp output and there is a short happening during power-up or reset, the over-current protection will be disabled during those transient times.

bfa001

 

 

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