• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 69 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.

LM5113: External R and C

Helmut Fischer
Prodigy 20 points
Part Number: LM5113
Other Parts Discussed in Thread: LMG1205

Hi,

in the data sheet of the LM5113 external R and C are shown in Fig. 16 (" Feature Description"). I am not shure, whether the R and C have to be adapted externally or whether they are included in the device and the figure just intends to explain the signal smoothing. So, should R (1k) and C (22p) be adapted externally?

Every answer is appreciated.

Best regards

Helmut

  • 0
    TI__Prodigy 400 points

    Hi Helmut,

    Thank you for your interest in LM5113. Have you considered the newer LMG1205? The LMG1205 is a pin-to-pin replacement to the LM5113 and takes the design of the LM5113 and includes enhancements that provide a more robust solution. 

    Regarding Figure 16, the low pass filter seen is meant to be an external filter for the inputs. 

    Regards,

    Zihao

  • 0 in reply to Zihao Ke
    Prodigy 20 points

    Hi Zihao,

    thank you very much for your answer! Unfortunately we are having difficulties to assemble (solder) LMG1205 in our lab. LM5113 is available in a WSON package, while LMG1205 only comes in a BGA package if I am right.

    Still one question about the data sheet of the LM5113: regarding the external filter it says 1 kOhm and 22 pF. Shouldn't it be 2.2 pF? 1k Ohm*22 pF gives 22 ns which appears to be very long. (Data sheet aims at avoiding pulses shorter than 3 ns.)

    Best regards

    Helmut

  • +1 in reply to Helmut Fischer
    TI__Prodigy 400 points

    Hi Helmut,

    Yes, the two devices come in different packages. Apologies for the oversight! 

    You are correct that the external filter has a much longer time constant than the pulses we are trying to avoid, but the filter can also eliminate any high frequency noise that might affect the signal going into the inputs. If you need to send pulses that are shorter than the time constant of this low-pass filter, you can adjust the values of the components or also use the filter seen in Figure 17.

    Let me know if you have any further questions. 

    Thanks,

    Zihao