Voltage Regulators BY: Wisdom Mahami| Mary Evenunye Gaewu

Outline 1.Introduction to voltage regulators 2.Types of Voltage Regulators 3.Principle of Operation 4.Basic circuitry 5.Advantages and disadvantages 6.Circuitry analysis 7.Real life application

Introduction A voltage regulator is an integrated circuit (IC) that provides a constant fixed output voltage regardless of a change in the load or input voltage. It can do this many ways depending on the topology of the circuit within.integrated circuit Types of Voltage Regulators There are two main types: Linear and Switching voltage regulators 1.Linear voltage regulators: Series and shunt 2.Switching VR: Step down(Buck),Step up (Boost),Inverter(Step down/step up)

LINEAR VOLTAGE REGULATOR Series Linear Voltage Regulator Shunt Linear Regulator

Mode of operation Linear voltage regulator

Circuit Analysis of Linear voltage regulator Thermal shutdown protection

WHAT CAN MAKE THE OUTPUT VOLTAGE FAULTY 1.The decoupling capacitors. Without a ripple appears in an oscilloscope 2.Short circuits The value of the decoupling capacitors is in the data sheet.The output capacitor(Small buffer for OV). For LM7805,330nF & 100nF are suggested by the manufacturer.

SWITCHING VOLTAGE REGULATORS

The Buck Switching Regulator Reduce DC voltage from higher to low Voltage regulation is obtained by varying the duty cycle with high switching speeds, up to 200 kHz Buck Converter Duty Cycle is given By:

The Boost Switching Regulator Converts DC voltage from lower to higher the output voltage from the boost converter depends upon the input voltage and duty cycle. Not also that this equation is independent of the value Of the inductor, the load current, and the output capacitor. The output voltage is given by:

The Buck-Boost Switching Regulator is a combination of the buck converter and the boost converter that produces an inverted (negative) output voltage which can be greater or less than the input voltage based on the duty cycle.the input voltage By voltage output is given by:

Real life application of Voltage Regulators 1.Charging of mobile phones ( 100V to 240V input and output of 5V ) 2.Computer power supply, it takes in 90V-240V and provides 12V, 5V, 3.3V, -12V for the system to run. 3. We have micro-controllers everywhere and almost all micro-controller runs on 5V and a very low current so in most cases a 7805(or 78L05) is incorporated with them to make sure that the controller runs properly. 4.For AC voltage regulator however you can find the voltage stabilizer that takes in a slightly fluctuating voltage and provides a stable AC voltage. This type of regulators are commonly used with freezers etc. 5.Almost every internal combustion engine has a device called a voltage regulator which help tame the alternator output. 6. The linear regulator is free of any switching noise, having ripple rejection capability and its low voltage noise, which makes the linear regulator of choice in such noise-averse applications as audio-visual, communication, medical, and measurement devices.