• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Subscribers 62 subscribers
  • Views 212 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM5176: Lm5176 overcurrent protection setting

SHENG YANG
Expert 1090 points
Part Number: LM5176

ALL HI！

I currently use lm5176 to design buck-boost circuit. How should I design overcurrent protection. I used lm5176 buck boost QuickStart tool R1.0 to design parameters, but I encountered a problem.

The input voltage I use is 8 ~ 36VDC and the output voltage is 12V / 3A. I hope the protection current is designed to 4A.As shown in the figure below.What input voltage should I use as the standard design sampling resistance. If the resistance Rs is too large, when 8V is input, 3A cannot be output, which will be protected. If 8V is used as the standard, the output protection current will increase when the input voltage increases. How should I calculate. Thank you.

Figure 1

Figure 2

  • +1
    TI__Guru 58225 points

    Hello Sheng,

    In the cell "Required IOCP(MIN)Setpoint at VIN(nom) we recommend to set 125% of the output current you need. BTW, I have seen that sometimes in Excel the comments that are in the cells with the red edges top right are not properly shown. Please use the Review tab in Excel which will give you the ability to show and hide the comments. I am sorry for this inconvenience.

    You are right, the available output current is then dependent on the input voltage. To overcome this you can use the Constant Current Loop, which needs a second resistor in the output path to limit the average output current to e.g. 4A.

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    Expert 1090 points

    Hello Brigitte!Thank you.!

    I fill the value into the table, as shown by the arrow in the figure. 4A overcurrent protection can be realized only when the input voltage is 8V. 24V and 36V inputs shall not be protected by current limiting. Therefore, 24V and 36V use the average current to realize current limiting?

  • +1 in reply to SHENG YANG
    TI__Guru 58225 points

    Hello Sheng,

    For additional current limit you need to add a second resistor to measure the output current. You need then to fill in the cell below the ones with the arrows with the average current you want to have and add the calculated resistor in the middle of the output capacitors.

    Best regards,
    Brigitte

  • 0 in reply to Brigitte
    Expert 1090 points

    Thank you!Brigitte!