• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 63 subscribers
  • Views 374 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.

TPS92640: Average LED current

K.Hamamoto
Guru 12155 points
Part Number: TPS92640
Other Parts Discussed in Thread: LM3409

Hi

On the datasheet figure 15 shows OTA circuit to minimize the offset voltage.

However there is no detail how this circuit works. Could you give me some more detail? 

Best Regards,

Koji Hamamoto

  • 0
    TI__Mastermind 28655 points

    Hello,

    If you use a comparator to detect a trip threshold the input offset for the + and - terminals can be compensated for by alternating swapping the inputs and output.  As an example only, if there is a 1 mV error on the input offset the alternating measurement of this offset will be +1mV, -1mV.  This averages to zero removing the input offset as a portion of the regulation error.  this will make the current ripple have a small component of alternating ripple levels:

    The LM3409 has a better description of this, datasheet page 11, it regulates peak current but the alternating measurement has the same affect:

    Regards,