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LMH6551Q-Q1: output voltage swing

KANJI SHIBATANI
Mastermind 6205 points
Part Number: LMH6551Q-Q1
Other Parts Discussed in Thread: TINA-TI, LMH6551

Hello

Please allow me fundamental quiestions.

My Customer intend to LMH6551Q-Q1, and need 3Vrms differential output swing with single supply.


Q1


We see data sheet page 5 following.


" Vs=+/-2.5V ,Vcm=0V : Output voltage  swing  +/-2.8V(TYP) "

Does it mean +OUT termnal= +1.4V, -OUT termnal =-1.4V ( or +OUT=-1.4V, -OUT= -1.4V)?


Q2

Is Output voltage swing same +/-2.8V(TYP) for V+= 5V, V-=0V,  Vcm=2.5V?

If no, Output swing should be approx 1.1V lower than V+, higher than V-?


Q3

Customer need 3Vrms differential output swing with single supply.


3V x sqrt(2)=4.24V

So, 2.12V peak should be necessary.


I think V+ >6.5 V and Vcm=3.3V ( 2.12+1.1V) should be necessary... How do you think?

We don't have TINA-TI .tsc file for LMH6551Q-Q1, but please advise.

Thank you


Best Regards

  • 0
    TI__Genius 15975 points
    Hi Kanji-san,

    To answer your questions:
    1. Yes. On a +/-2.5V & Vcm = 0V, an output voltage swing of +/-2.8V (typ) means that the OUt+ terminal = +1.4V & OUT- terminal = -1.4V (or vice-versa).
    2. Yes. The output voltage swing is same +/-2.8V (typ) for V+ = 5V, V- = 0V, Vcm = 2.5V. This could also be interpreted as the output swing on single-ended output is limited to approximately 1.1V lower than V+ or 1.1V higher than V-, and is irrespective of whether the supply is +/-2.5V or +5V as long as the Vcm is set to mid-supply.
    3. The LMH6551Q-Q1 can easily achieve the 3Vrms differential output swing with single supply, or essentially 4.24Vpp(diff). On a single +5V supply with Vcm = 2.5V, the part can achieve maximum differential output swing of +/-2.8V or 5.6Vpp(diff).

    You should be able to use the LMH6551 TINA-TI model which should be very similar to the LMH6551Q-Q1 part model. The LMH6551 TINA-TI model should be available in the FDA Spice macros when you install TINA-TI on your computer for the first time.

    Best Regards,
    Rohit
  • 0 in reply to Rohit Bhat
    Mastermind 6205 points
    Deat Rohit san
    Thank you for your answer. Sorry for my late reply.
    Thank you