rectifierrecoverytime

Rectifier Recovery Time

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This page shows the difference in switching noise generated by 2 different diodes (standard 1N4007 vs Schottky 1N5819) in a half wave rectifier circuit when it goes out of conduction. Also shown for comparison is the standard diode with a 100nF snubber capacitor in parallel.

Here's the circuit used to compare the diodes. A high speed DSO (Tektronix TDS 754A 500MHz 2GS/s) and a Tektronix P6139A x10 probe were used to measure the voltage across the diode. The total length for the scope probe tip and ground was less than <1cm to minimize any error. The AC source for the test circuit is a walwart transformer, the DSO doesn't need isolation from the AC line because of this.

For each case, 3 different horizontal scales were shown for clarity. The vertical scale and trigger point remains identical for all captures.

1N4007:

Note the amplitude of the ringing is over 10V and the very fast rise and fall time.

1N4007 (plus 100nF across ) :

1N5819:

From the scope captures, one can conclude that a 1N4007 standard diode without the snubber has a higher amplitude of the reverse recovery pulse (which will generate more high frequency noise) compared to the other 2 configurations. The RF content across the AC secondary line (not shown) of the 1N4007 w/o the snubber actually extends beyond 1MHz when viewed from a spectrum analyzer. The bulk of the power is concentrated at 600kHz and below.

Adding a 100nF snubber capacitor across the 1N4007 reduces the diode recovery switching amplitude and increases the pulse width.

When the standard diode was replaced with a Schottky diode, we see a significant drop in the recovery switching pulse level but the width stays the same.

first upload: Oct 27, 2009, 8:27 AM data was available 2 years prior

edited: June 15, 2011, 06:40PM PST May 12, 2014 09:55AM PST

add original upload date: Dec 4, 2017 9:49AM PST

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