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ALM2402F-Q1: ALM2402F-Q1

Stefano Casilli
Prodigy 60 points
Part Number: ALM2402F-Q1
Other Parts Discussed in Thread: ALM2403-Q1

Tool/software:

Hello,

i'm using the ALM2402F-Q1 to amplify a  0-3V signal at 29kHz to get a 8V signal to a 50ohm load. To this purpose i performed a simulation with Tina using TI device model and powering the device at 12V on positive supply and -3.3V on negative supply and the circuit seems to work properly (negative voltage is used to read the 0V at the input side of course). The question is: may i supply the device this way or it is possible to supply it only with positive to GND supply? And in negative case the is the correct device to be used the ALM-2403?

kindest regards

Stefano Casilli

  • 0
    TI__Genius 14536 points

    Hey Stefano,

    You can absolutely use the device in split supply, though most customers do tend to use single supply. Remember, the SHDN circuitry is referenced off of the V- rail, so some of these voltages may need to level shift to still be in the desired range you want.

    Another gotcha is the thermal pad. This is electrically connected to V-, not GND. This becomes further becomes confusing as the datasheet routinely denotes the negative supply pins as "GND", whereas they are truly V- pins. Again, 98% of customers use these devices in single supply, so much of the datasheet is written in that context. ALM2403-Q1 is very similar architecture to the ALM2402F-Q1, but both have their advantages depending on application. 

    I am happy to review a circuit if you have one designed up.

    Thanks,

    Jacob

  • 0 in reply to Jacob Nogaj
    Prodigy 60 points

    Thank you Jacob: the circuit  simply multiply for 2 the 28.8kHz sinusoidal voltage at its input working with a 50ohm load at the output. In the circuit i put the SHDN circuit at GND because the V- is -2.5V (and so the SHDN is 2.5V over V-

    Here is the circuit

    Regards

  • 0 in reply to Stefano Casilli
    TI__Genius 14536 points

    Hey Stefano,

    Very nice design, this will work well. You are correct regarding the SHDN voltage, GND conveniently works as an enable voltage in this setup. 

    Just me, but I might put a footprint down for a CF in parallel with the 10k feedback resistor just in case I need to play around with limiting the bandwidth for stability reasons.  

    Feel free to reach out if you have any other questions.

    Best,

    Jacob

  • 0 in reply to Jacob Nogaj
    Prodigy 60 points

    Ok Jacob i will use a capacitor to limit the bandwidth

    thanks for helping

    regards

    stefano