Saturday, April 07, 2012

Diode recovery time

Understanding the parameters of "diode recovery time" .For prospective technicians are still learning and inexperienced, they generally recognize only two kinds of parameters of a diode, namely:
  • The maximum working voltage (bias voltage when he gets back - or when not deliver - or when "off")
  • The maximum operating current (when he gets a forward bias voltage of - or as leads - or when "on")
Understanding the parameters of "diode recovery time"
Fast Recovery diodes
A similar experience we had some twenty years ago when a new SMPS first introduced on the television. When there is a diode voltage B + is broken. And then we replace the diode from the outside (our point of diode being sold in stores, rather than the official service) diode turns hot and soon broken. We think that the replacement diode voltage or current is less bulky. Then after replacement with a larger, but the result remains the same damage. Finally we order the diode with the same part number, and when the part arrived and was installed wrong results immediately.

Then why the diode is purchased in the market is hot and faulty? Actually there are many other parameters that have a diode. One more thing to be understood by a technician is called a "diode recovery time".
Common diode rectifier is used for the power supply circuits of 50Hz, when he gets forward biased diode voltage will deliver ("on"). Then, if the bias voltage is turned upside down then the diode does not turn into leads ("off"). If the diode is then mounted on a high-frequency ac voltage. So when given the diode forward bias voltage will deliver ("on") as usual. But when the bias voltage is turned upside down, apparently indirect diode can turn into "off" quickly. 

There is a delay of a minute to "off" so that when the bias voltage is turned "off" there is still a bit of reverse leakage current. If the frequency of the ac leakage current was further compounded the greater the return. Reverse leakage current is what causes the diode to be hot.
Diode recovery time is a parameter of a diode which shows the "time" needed for the change of position "on" to "off" position. The smaller the value the better the recovery time is used at high frequencies.


Based on the parameters of the diode recovery time, then this type of diode is classified into:
  • Diode general, for the rectifier AC voltage
  • Fast Recovery Diode, used in the circuit and the flyback SMPS with a frequency of approximately 35 Khz
  • Super Fast recovery diode, used in SMPS circuits with a frequency of about 70 to 80 Khz.
  • Tips to find the diode equation.
  • If we can not get the diode with the same part number, then we will usually replace it with another part number. We will replace the diode with the diode used in the same location. For example, diode B +-A model of the television is broken, then we will replace the B + diode that is used by television B or C.

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