Voltage Regulators

Electronic components are highly sensitive to voltages and currents across them. Most of the devices in the current market work in the voltage levels of 3.3V, 5V, 12V and 15V. If they are provided with a different voltage than the one required by the vendor, they would not function. If the voltage supplied is higher, they might burn off. The PSLab device requires separate voltage levels such as 3.3V and 5V for its operation. There are commercial voltage regulators available in the market designed with advanced feedback techniques and models. But we can create out own voltage regulator. In this blog post, I am going to introduce you to a few basic models capable of regulating voltage to a desired level. Current implementation of PSLab device uses a voltage regulator derived using a zener-resistor combination. This type of regulators have a higher sensitivity to current and their operation may vary when the supplied or the drawn current is lower than the expected values. In order to have a stable voltage regulation, this combination needs to be replaced with a much stable transistor-zener combination. Before go into much details, let’s get to know a few basic concepts and devices related to. Zener Diode Zener diode is a type of diode which has a different operational behavior than the general diode. General diodes allow current to flow only in one direction. If a current in the reverse is applied, they will break and become unusable after a certain voltage level known as Breakdown Voltage. But Zener diodes are specifically designed to function desirably once this break down voltage has been passed and unlike general diode, it can recover back to normal when the voltage is removed or reduced. Transistor This is the game changing invention of the 20th century. There are two types of Bipolar Junction Transistors (BJT) available in the market. They are known as NPN and PNP transistors. The difference is based on the polarity of diodes used. An NPN transistor can be modeled as a combination of two diodes --[NP → PN]-- and a PNP transistor can be modeled as --[PN → NP]-- using two diodes. There are three pins to take notice in BJTs. They are illustrated in the diagram shown here; Base Collector Emitter The amazing fact about BJTs is that the amount of current provided to the Base terminal will control the flow of current going through Collector and Emitter. Also note that always there is a voltage drop across the Base terminal and the Emitter terminal. This typically takes a value of 0.7 V Voltage Divider This is the most basic type of voltage regulator. It simply divides the voltage supplied by the battery with the ratio R1:R2. In the following configuration, the output voltage can be calculated using the voltage division rule; Which is equal to 12 * 100/(100+200) = 4 V There is a huge drawback with this design. The above calculation is valid only if there is no load impedance is present…