sarjasäätimet

Sarjasäätimet, also known as series regulators, are electronic components used to maintain a constant output voltage regardless of changes in input voltage or load current. They are typically implemented using a pass transistor, such as a bipolar junction transistor (BJT) or a metal-oxide-semiconductor field-effect transistor (MOSFET), and a voltage reference. The pass transistor acts like a variable resistor, adjusting its resistance to compensate for variations and keep the output voltage stable.

The basic principle of operation involves a feedback loop. A voltage divider circuit samples the output voltage and compares it to a stable reference voltage. Any difference between the two is amplified and used to control the conductivity of the pass transistor. If the output voltage rises above the desired level, the pass transistor's resistance increases, reducing the current flow and bringing the voltage back down. Conversely, if the output voltage drops, the pass transistor's resistance decreases, allowing more current to flow and raising the voltage.

Sarjasäätimet are relatively simple in design and offer good regulation performance. However, they are not very efficient, especially when there is a large difference between the input and output voltages. The excess voltage is dissipated as heat in the pass transistor, which can lead to significant power loss and require heat sinking. Despite this inefficiency, they are widely used in applications where cost-effectiveness and simplicity are prioritized, such as in power supplies for consumer electronics and low-power circuits.