1.3 Diode Data Sheet Interpretation

A data sheet for the popular 1N4148 switching diode is shown in Figure 1.3.1. The 1N4148 is designed for high speed operation required in high frequency signal applications but also finds use in a variety of general purpose applications that do not require very high current or power handling.

Some of the key features include a four nanosecond switching speed, a maximum reverse voltage of 100 volts and a 450 milliamp maximum forward current (with short single pulses as high as four amps being possible). Power dissipation is 500 milliwatts.

Referring to Figure 1.3.1b, the variation in reverse current with regard to temperature is obvious. This also verifies the “doubles every 10 C∘ ” rule-of-thumb.

 

Accessible version of Data Tables in Figures 1.3.1

Power derating and permissible pulse amplitudes can be seen in Figure 1.3.1d. Finally, note the variation in the forward voltage curves due to temperature. As stated previously, for a given current, an increase in temperature results in a lower forward voltage. Also, at room temperature, we see a knee voltage of approximately 0.7 volts.