• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 47 subscribers
  • Views 887 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

LM358: LM358 design

user5975063
Prodigy 80 points
Part Number: LM358

Hello,

I want to know as below design about LM358 design is ok or not?

for Pin5,pin6 and pin7 we don't use the function

only use pin1,pin2 and pin3 for design.

This circuit we use for LCD backlight power. our customer find some problem about this design.

Please help check what's cause will lead to as below result?

the LM358 pin2 have same input, but  the C206.1 have different result 

  • 0
    TI__Guru**** 165376 points

    Hello, User 

    Q27 can only source current so an external source could be pulling up the voltage and U28, Q27 can't stop that.

    A more likely scenario is that this circuit broke into oscillation. Q27 provides voltage gain and C206 provides lag, both of these effects will be bad for stability.

    Check pin 1 with an oscilloscope to get a good look at the oscillation waveform.