GuideCircuit : Free Electronics Circuit

Power Supply Design

Linear DC Power Supplies

Linear power supplies are based on the concept of taking an input voltage and converting it to an appropriate level of DC voltage that exceeds the required output voltage. This voltage is then regulated down to the specified power supply output voltage. If the linear supply is a regulating supply, it monitors the output voltage and varies its resistance accordingly to provide the required output voltage.

Power Supply Design

Introduction

Power supply spec

Linear power supplies

DC-to-DC converters

Switching supplies

Inverters

Power Supply Relate

Power Supply Circuit

Step-Up DC-DC Converter

There are two basic varieties of linear regulators, series and shunt regulators. Shunt regulators are represented by a series resistance with a regulating mechanism, usually a semiconductor, whose resistance is varied to draw more or less current in a circuit path that is in parallel with the load, thereby adjusting the output voltage to the required level. As the load resistance changes, the shunt regulator diverts more or less current through this parallel path (Figure 1).

The efficiency of the shunt type regulator is low when the load current is small (load resistance is high) because a large current is diverted through the regulator. This current isn’t doing any work except regulating the output. When the load current approaches full load conditions for the power supply, the efficiency is much higher. A key advantage of the shunt regulator is the fact that when the load is a short circuit, the power supply will not be short-circuited.

Figure 1 Shunt regulator

Figure 2 shows a series regulator with the regulating mechanism in series with the load. The series regulator has the opposite characteristics as compared to the shunt regulator. The efficiency of the series regulator is low when the load current is at full load levels and high when the load current is low. When the load becomes shorted, excessive current is drawn from the supply. Series regulators are used much more often than shunt regulators. When a regulator is to operate very near full load condition most of the time and there is a possibility of the load becoming shorted, a shunt regulator becomes a viable option

Figure 2 Series regulator

Home Circuits Software Articles Link