Discussion Overview
The discussion revolves around the physics and practicalities of voltage regulators, specifically in the context of generating a -5V output from a +5V supply. Participants explore the capabilities and limitations of specific voltage regulator models, including the LM7905 and LM7805, and discuss alternative methods for achieving negative voltage outputs.
Discussion Character
- Technical explanation
- Debate/contested
Main Points Raised
- One participant, Chet, seeks a detailed explanation of how a voltage regulator can create a -5V signal from a +5V and ground, specifically in relation to the LM7905.
- Another participant asserts that the LM7905 cannot generate -5V from +5V and ground, as it requires a raw negative voltage more negative than -7V.
- Chet later corrects the initial mention of the LM7905 to the LM7805, which another participant clarifies outputs +5V, not -5V.
- Discussion includes the concept of creating a "virtual ground" to derive both +5V and -5V from a higher positive voltage supply, indicating the complexity of converting positive to negative voltages.
- One participant suggests that while there may be DC to DC converters capable of converting +5V to -5V, they typically require additional components like inductors.
- Another participant mentions switched capacitor converters as a potential solution for low current applications, referencing specific models from Linear Technology.
Areas of Agreement / Disagreement
Participants generally disagree on the feasibility of generating -5V from +5V using the discussed voltage regulators, with no consensus on a straightforward method to achieve this without additional components or configurations.
Contextual Notes
The discussion highlights the importance of understanding voltage references and the relative nature of ground in circuit design, as well as the limitations of specific voltage regulator models in achieving desired outputs.