Discussion Overview
The discussion revolves around designing a foldback current limiter circuit with specific parameters: a maximum current limit of 3 Amperes, a short circuit current limit of 1 Ampere, and an output voltage of 28 volts, which is the same as the input voltage. Participants are exploring the challenges and considerations involved in this design, including thermal management and component selection.
Discussion Character
- Technical explanation
- Debate/contested
- Experimental/applied
Main Points Raised
- One participant expresses the difficulty of designing a current limiting circuit with equal input and output voltages, noting the need for a voltage drop across a current sensing resistor and a series pass transistor.
- Another participant specifies that the maximum tolerable output voltage drop is 0.5 volts, indicating that the output voltage should not fall below 27.5 volts under normal conditions.
- Concerns are raised about the heat generated by MOSFETs during foldback current limiting, with one participant reporting that their MOSFETs become very hot, leading to increased current despite using heat sinks and parallel configurations to manage thermal issues.
- There is a discussion about the possibility of setting the short circuit current limit to less than 1 Ampere, with one participant stating that there is no strict limit but it should not exceed 1 Ampere.
- Participants discuss the labeling of transistor part numbers in the circuit design, with one admitting to interchanging the part numbers of MOSFETs and transistors.
Areas of Agreement / Disagreement
Participants do not reach a consensus on the feasibility of the proposed design parameters, particularly regarding the thermal management of the MOSFETs and the implications of having equal input and output voltages. Multiple competing views on the design challenges and component specifications remain evident.
Contextual Notes
Participants mention limitations related to thermal dissipation and the need for specific voltage tolerances, which may affect the overall design and functionality of the circuit. The discussion includes unresolved aspects of the circuit design process, particularly regarding the handling of heat and the selection of appropriate components.