Creating a Virtual Ground for Opamp Circuits
Virtual Ground: In scenarios where only a single power supply is available for an opamp circuit, a challenge arises as these circuits typically require a double supply. To tackle this issue, the available supply must be converted, usually accomplished through a potential divider and a capacitor placed across the single supply, sometimes assisted by an additional opamp.
Modern Solution: TLE2426 from Texas Instruments
In contemporary applications, a more advanced approach involves using the TLE2426 from Texas Instruments. This integrated circuit offers significant advantages. Not only is it compact and user-friendly, but it also incorporates a built-in opamp, enhancing overall performance. This improvement becomes especially evident at low frequencies, where the impedance of the conventional electrolytic capacitor across the potential divider might pose challenges. In the TLE2426, a voltage follower replaces the capacitor, ensuring low impedance even at low frequencies, typically maintaining it at 7.5 mΩ. The quiescent current is a mere 170 μA, and it can provide a peak current of up to 20 mA.
Different Enclosures for Versatile Applications
The device is offered in two distinct enclosures: one resembling a transistor, denoted by the ‘LP’ suffix in the type number, and the other in S-pin DIL format, identified with D, P, or JG suffixes. The LP variant is highly suitable for replacing conventional potential dividers and capacitors (and potentially Tamp). On the other hand, the D1L version allows the connection of a capacitor to its pin 8, a desirable feature in cases where each of the two output voltages is half the supply voltage, which might contain significant noise.
Introducing Type TLE2425
Another option available is the Type TLE2425, providing a fixed voltage output of 2.5 V at a peak current of 20 mA. Unlike the previous models, pin 8 of this version remains unconnected.
Understanding Operational Amplifiers
An operational amplifier, often abbreviated as an op-amp, is an integrated circuit designed to amplify weak electric signals. It features two input pins and one output pin, with its primary function being to amplify and output the voltage difference between the two input pins. Op-amps are commonly utilized as voltage amplifiers, with noninverting and inverting configurations being the basic types. Among these, voltage followers, also known as buffers, are frequently employed in noninverting amplifiers. Additionally, op-amps find applications as differential amplifiers, integrator circuits, and more.