Voltage Regulator Selection And Key Parameters?
A voltage regulator is an integrated circuit (IC) that provides a permanently fixed output voltage regardless of the load or input voltage change. From your cell phone charger to the air conditioner to sophisticated electromechanical devices, almost all electronic devices use voltage regulators to supply different DC voltages to different components of the device. Besides, regulator chips are used in all power supply circuits.
For example, in your Smartphone, a voltage regulator is used to increase or decrease the battery voltage (such as LED backlight, mic, SIM card, etc.). Choosing the wrong voltage regulator can result in compromised reliability, high power consumption, and even bent components.
So in this article, we will discuss some important parameters to keep in mind while choosing a voltage regulator.
Important factors for voltage regulator selection
Input voltage and output voltage
The first step towards choosing a voltage regulator is to know the input and output voltage that you will be working with. Linear voltage regulators require an input voltage higher than the rated output voltage. If the input voltage is less than the required output voltage, then it leads to insufficient voltage status, which causes the regulator to drop and provide an unmanaged output.
For example, if you are using a 5V voltage regulator with a 2V drop-out voltage, then the input voltage must be equal to at least 7V for one regulated output. An input voltage below 7V will result in an irregular output voltage.
There are different types of voltage regulators for different input and output voltage ranges. For example, you would need a 5V voltage regulator for the Arduino Uno and a 3.3V regulator for the ESP8266. You can even use a variable voltage regulator that can be used for output applications.
Drop out voltage
The difference between the drop voltage input and the output voltage of the voltage regulator. For example, the input voltage for 7805 is 7V, and the output voltage is 5V, so it has a drop-out voltage of 2V. If the input voltage goes down, the output voltage (5V) + the drop output voltage (2V) will result in an unregulated output that could damage your device. So before selecting a transformer, check the dropout voltage.
Dropout voltage varies with voltage regulators. For example, you can find a range of 5V regulators with different dropout voltages. Linear regulators can be very efficient when they operate with very low input drop-out voltage. So if you are using the battery as a power source, you can use LDO regulators for better performance.
Power consumption
Linear voltage regulators consume more power than switching voltage regulators. Excessive power consumption can damage the battery drain, excessive heat, or the product. So if you are using a linear voltage regulator, first calculate the power consumption.
You can use switching voltage regulators instead of linear voltage regulators to avoid power outages.
Performance
Performance is the ratio of input power to output power, which is proportional to the ratio of the output voltage to the input voltage. Therefore, the performance of voltage regulators is limited by direct dropout voltage and calm current because of the higher the dropout voltage, the lower the efficiency.
For high efficiency, the drop output voltage and the calm current should be kept to a minimum, and the voltage difference between the input and output should be kept to a minimum.
Voltage accuracy
The overall accuracy of the voltage regulator depends on the line regulation, load regulation, reference voltage drift, fault amplifier voltage drift, and temperature coefficient. Typical linear regulators typically specify the output voltage which guarantees that the regulated output will be within 5% of the nominal output. So if you’re using a voltage regulator to power a digital IC, 5% tolerance isn’t a big deal.
Load regulation
The load regulation is defined as the ability of a circuit to maintain a specific output voltage under load under different conditions. Expressed as load regulation:
Load Regulation = ∆Vout/ ∆Iout
Line regulation
Line regulation is defined as the ability of a circuit to maintain a specific output voltage with different input voltages. Expressed as line regulation:
Load Regulation = ∆Vout/ ∆Iout
Therefore, in order to select the appropriate voltage regulator for any application, one should take into account all the above factors.
