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[ LM48560 ] Single-Ended Input

Kenichiro
Mastermind 9165 points
Other Parts Discussed in Thread: LM48560

[ LM48560 ] Single-Ended Input

Hi there,
Can anyone help me to answer following questions?
My customer who uses LM48560 with differential input is now trying to change their circuit to single-ended input.
It is stated in the datasheet that, for single-ended configuration, DC block cap and a cap for unused input.

Q: How can we figure out the value of a cap for unused input? Is it necessary to use same value with DC block cap?
Q: Also, is it possible to connect unused input to GND without any cap?
Q: Datasheet suggests to use IN- for single-ended input, but is is okay to use IN+ instead?
Thank you for your support in advance.

Regards,

Ken 

  • 0
    TI__Intellectual 1240 points

    Hello Kenichiro-san,

    I'll make some comments to your questions about single ended input.

    Q: How can we figure out the value of a cap for unused input? Is it necessary to use same value with DC block cap?
    Ans: Yes, you need to use the same value with DC block cap
    Q: Also, is it possible to connect unused input to GND without any cap?
    Ans: No, to keep the same DC bias for both In+ and In-, you need to use the same cap value for unused input side.
    Q: Datasheet suggests to use IN- for single-ended input, but is is okay to use IN+ instead?
    Ans: You can input the signal to IN+ via DC block cap and IN- pin need to use the sama cap value to GND.
     
    Please note that if customer use ALC function in differential inputs, you will keep differential inputs configuration to work ALC function well. But when you take single ended input configuration, ALC function doesn't work well.
     
    Best regards
    T NAOKAWA
     
     
     
  • 0 in reply to Toyojiro Naokawa
    Mastermind 9165 points
    Hi Naokawa-san,
    Thanks for your reply, it's helpful for me.
    Thanks,
    Ken