Effective Load Resistance

Posted on Feb 7, 2014

This article offers an alternative to efficiency measurements as an evaluation tool of power supplies. The proposed method works well with little dependency on the output voltage and temperature. Power supplies have always been evaluated and compared based on the how efficient the conversion process is. Equations 1 and 2 are two of the most used f

Effective Load Resistance
Click here to download the full size of the above Circuit.

ormulae to calculate the power conversion efficiency ·. The use of efficiency as a yardstick to evaluate DC-DC converters represents a very simple and in most cases effective way of comparison. Efficiency figure combined with the details of the converter parameters also allows the thermal engineer to calculate the thermal load of the converter and whether heatsink and/or cooling airflow is required. The efficiency tool works very well when we have established standard input and output voltages that are more or less fixed in value. We will show that the efficiency alone is not the right tool to compare converters operating at different output conditions even with a fixed input voltage and switching frequency. We will explain why that is and propose an alternative methods that measures the performance almost  independent of the output voltage that gives a much more accurate and unambiguous idea about the converter`s performance so we introduce the concept of the Effective Loss Resistance, Rol. Figure 1 depicts a simplified block diagram of a synchronous buck converter used in the evaluation of this paper. It is worthwhile mentioning that this work may be adapted to almost all DC-DC converters. Figure 2 shows the efficiency of a given converter at different output voltages. Although the power loss is mainly dependant on the load current at a fixed switching frequency and input voltage and is very lightly dependant on the...

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    Advanced Volume control
    RF isolation amplifier
    oscillator How to control a speaker
    Saturating a N-Channel MOSFET
    led strip Using a N-Mosfet to switch a common cathode ledstrip
    Parallel Port Interfacing and Programming
    Power audio amplifier schematics with Tda2005
    sine wave oscillator
    Peak Reading Audio Level Meter
    PGA202 / 203 digitally controlled programmable gain instrumentation amplifier circuit
    Over-temperature alarm circuit
    Blinker circuit 2