Why is output impedance important?
A power supply is a source of current from a fixed voltage. Any impedance at the power supply output (zout) is in series with the load impedance being driven by the supply. The supply impedance and the load impedance form a voltage divider, so as the load requests current from the supply, the voltage at the load will change by the amount zout * iload.
Thus lower zout delivers fundamentally better voltage regulation. Watch the first three minutes of this video from Texas Instruments to learn more.
SPX Output Impedance vs. Frequency
What is Superpower's output impedance? Amazing! Here is a graph of Zout vs. frequency, showing a 50mΩ maximum impedance while delivering 10mA from 20Hz to 200KHz. This is measured on a typical production SPX78 with 12V out.
What are we showing you?
In this test, a 10mA AC current is pulled from the regulator output (top trace, at 10mA/div), as frequency of the current is swept from 20Hz to 200kHz. The AC voltage appearing at the output of the regulator (bottom trace at 50mΩ/div by using a gain of 1000 amplifier) represents the output impedance, where zout=vac/iac. Voltage is graphed on an oscilloscope where you can see frequency change across the horizontal axis at 20kHz per division.
SPX zout stays low across ten times the audio band. We dare you to find or build a better regulator! Take a look at our Zout comparison page to see how SPX compares to other available voltage regulators.