• State TI Thinks Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 47 subscribers
  • Views 131 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.

Original question:

LF398-N: Sample and hold circuit with the LF398S8 is not working

LF298: LF298

Nagendra Kumar
Prodigy 10 points
Part Number: LF298

Hi, 

We are testing LF298M for a basic S&H Application. We are using +/- 15V for supplies to measure a signal range of 0-10V.

Logic reference is connected to GND and 5V signal is given as logic high.

Whenever logic pulse is given output is fixed at -15V .

I saw a similar thread for LF398 and posting this message. I am using the same schematic given in the first page of the schematic.

Please do support on this issue.

Thanks and Regards,

Nagendra Kumar

  • 0
    TI__Guru 52756 points

    Hi Nagendra,

    Nagendra Kumar said:
    I saw a similar thread for LF398 and posting this message. I am using the same schematic given in the first page of the schematic.

    Regarding the LF398S8 question referred on the previous E2E query, please note, the LF398S8 is not produced by TI, but by a different manufacturer. Hence the previous query is not related to a TI product. I could not find schematics provided on this post, or the previous post.

    Kindly provide the LF298M schematic.  A circuit schematic showing the supply connections, bypass capacitors,  hold capacitor value, offset pin connection, the source or circuit driving the input of the LF298, and output load of the LF298 would be helpful.

    Also, if you can please provide an oscilloscope of the input signal (pin3), the logic input pulse (pin 8), and output signal (pin 5) that would provide us more information to help debug the issue.  Please place the oscilloscope probes right at the pins of the device referred to the same GND of the LF298M circuit.  Also, please let us know how many devices show this issue.  Is this a PCB or a prototype board?

    Thank you and Kind Regards,

    Luis

  • 0 in reply to Luis Chioye
    TI__Guru 52756 points

    Hi Nagendra,

    I have not heard from you, I assume the issue was resolved.  However, if the issue persists, please provide the schematic and oscilloscope plots listed above, and we will be happy to assist.

    Thank you and Regards,

    Luis