Fixed vs Adjustable Voltage Regulators
A voltage regulator IC stabilizes voltage in a circuit, even when the input voltage or load current changes. Two common ICs that are classed in this area are fixed and adjustable regulators.
Fixed Voltage Regulators
These types have a set output voltage such as 3.3V or 5V. They are typically used in things like microcontrollers, sensors, and embedded systems. An example of this would be part number SPX3819M5-L-3-3/TR from MaxLinear, Inc.
Why Would I use this Type?
A few key points about using fixed regulators are:
- Less external components
- Simplifies the design
- One fixed voltage
Adjustable Voltage Regulators
These types allow external resistors to determine the output voltage. They are typically used in prototyping, custom analog circuits, and designs needing voltages like 2.8V, 4.1V, or 6V. An example of this would be part number SPX3819M5-L/TR.
Why Would I use this Type?
Here are a few points that explain why you would use this in your design:
- Flexible output voltage
- One regulator can support multiple designs
- Useful for uncommon voltages
Comparing the Two Product Examples
In this post, I used two different examples from the same supplier. Although their part numbers are very similar, they belong to two different types that can be used for different applications.
Part number SPX3819M5-L-3-3/TR has a fixed output voltage of 3.3V, whereas part number SPX3819M5-L/TR has an adjustable output.
I provided a link of the comparison for each product below:
Short Conclusion
If your design only needs 3.3V, the fixed version is a great solution. If the design could use a flexible range of different voltages, the adjustable version is the better option. The choice you make will come down to whether a single output is required or if output flexibility is more important for the circuit.