Timeless Wisdom: 1979’s Evergreen Application Note
Certain application notes stand the test of time. This particular one, originating from the ancient year of 1979, remains as pertinent as ever. It continues to captivate those seeking insights in this area. Opamps, while incredibly useful, possess limitations in current delivery, usually maxing out around 10 mA. When demands exceed this threshold, parallel connections of multiple opamps may seem like a solution. However, this approach often falters due to the inherent disparities between opamps. Their lack of perfect equality leads them to clash, resulting in little more than a tepid outcome—hardly the intended effect.
Fine-Tuning Current Delivery: Parallel Opamps Circuit
In this configuration, IC1a takes charge as the primary operator, supported by IC1b and IC1c, or as many stages as the situation demands. IC1a directs current to the load RL through R1. The ‘helper opamps’ are intricately linked to the voltage drop across R1. This arrangement ensures identical current delivery across all stages, thanks to the consistent values of resistors R4 and R5. However, vigilance against oscillation is crucial—a well-placed RC network (R5-C1) across the load can effectively prevent unwanted fluctuations.
The circuit is versatile and accommodates both symmetrical and single-ended power supplies. In single-ended setups, connecting the negative lead of the power supply to 0 V is essential for proper functioning.
Additionally, IC1a can be configured as an amplifier by incorporating the dotted resistors. To achieve unity gain, omit R3 and use a wire link for R2, tailoring the circuit to specific amplification requirements.
The Role of Resistors in Electronic Circuits
Resistors, fundamental two-terminal components, introduce electrical resistance into circuits. They find diverse applications, such as limiting electric current, dividing voltages, adjusting signal levels, generating heat, matching components, controlling gain, and setting time constants. Resistors come in an extensive range of resistance values, spanning nine orders of magnitude, and play crucial roles in electronic circuits by opposing current flow and creating voltage drops across terminals.