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LMV762 specs

Aaron Spaete
Expert 4330 points
Other Parts Discussed in Thread: LMV762

Team,

My customer has two questions regarding the LMV762MM. Please refer to the datasheet, document # SNOS998H, revised March 2013. First, regarding the table "5.0V Electrical Characteristics" on page 5,

1.  Can you please provide the min/max values for Vo (output voltage) when there is no current into/out of the output pin? Second, refer to Figures 15-16 on page 8. The graphs seem to contradict the earlier Vo parameter I mentioned. I would have expected that the output voltage would be zero (assuming a logic low state) for zero current and be slightly higher for a large amount of output current due to the RDS-On of the output FETs. The output should always be trying to drive either 0 or VCC, so it isn't clear why 2.5 VDC would ever be a valid output value. Can you please provide explanation?

2.  Finally, I would note that Figure 15 seems to have a typo. The title of the figure is "ISource vs. Vout" but the Y-Axis is labeled "ISink"

  • 0
    TI__Guru 53316 points

    Greetings Aaron,

    #1. The 2.5V comes from the fact that the devices are tested under split supply conditions on the tester. Unfortunately, the creators chose to specify the output like an op-amp with the comparator output returned to mid supply. This is typical for op-amps, but not comparators where, as you noted, the output load is rarely returned to 1/2 supply. I would not have specified it this way.

    As long as you realize the output is being returned to half the supply, you can calculate the actual current in/out of the pin if it is specified as a resistive load (i.e. "10Kohm").

    If it is a "current load" (i.e. "2mA"), like the LMV762 DS,  it really makes no difference since the load is a current sink/source and makes no matter if it is a 2.5V or 5V compliance. The important number is the volts to the rail at a specific current.

    Boy..I really do not like those graphs (figs 15-18). Just remember that the sink/source point is 2.5V (for 5V graph) and that the current is sink/sourced from that point. So "zero" current is actually 2.5V, and past 2.5V, you go into the "other" graph.

    You are correct. The output swing is determinate on the load current due to RDS-on of the output devices. With light loads (<100uA), the output should be swinging within several millivolts of the rail. 10mV is generally a safe number to expect with little or no load.

    #2. Yep. You are right. We have put in a request to get it corrected.