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TLE 2426 Precision Virtual Ground

user4725411
Prodigy 10 points

Other Parts Discussed in Thread: TLE2426

Hello, I have a board that uses TLE 2426 to split a single supply so that it can produce +/- 4.5V from a single 9V battery. I have the 8 pin version that has the noise reduction pin on pin 8. According to the datasheet, a 1 uF capacitor should be connected to pin 8 in order to take advantage of the noise reduction pin. However, I have been having problems with using that pin 8. It seems like TLE 2426 stops working properly whenever I connect a capacitor to pin 8. Any suggestions?

Thanks in advance.

  • 0
    TI__Guru* 93105 points

    Hello,

    The TLE2426 is usable with a CNR of 1 uF attached to the NR pin. CNR is charged by the upper input divider resistor at power-up and that time constant might be long with a 1 uF value. It will take about 5 time constants for the TLE2426 output voltage to approach the level that develops at the center of the input voltage divider. 

    The datasheet provides little information about the applying CNR in an actual circuit. There are noise and ripple rejection improvements gained from employing it, but the basic CNR connection has a startup time pitfall. My colleague, Tim Green, wrote a blog about applying CNR that provides information about improved startup performance while maintaining the advantages of including it. You can find the blog here:

    Another possibility is that the TLE2426 is unstable and oscillates with your particular combination of output load capacitance and load current. Datasheet Fig 17 provides a graphical view of output capacitance and current levels that result in stable, or unstable, operation.

    Regards, Thomas

    PA - Linear Applications Engineering