1N4739A

Zener diode also known as avalanche diode or breakdown diode, is a specific type of diode that permits current to flow in the forward direction, making it a regular diode. But, unlike regular diode, the Zener diode also allows the current to move in a reverse direction – when the Zener voltage is exceeded.

The Zener diode 1N4739A is a silicon epoch based voltage regulator with a breakdown voltage of 39V. This device is specifically designed to enable the user to adjust voltages between two levels. The 1N4739A was picked as a regulator due to its low temperature coefficient as well as having an exact voltages up to 39V. It has a continuous reverse voltage of 50VRMS and has a forward voltage drop of 1.35V.

In terms of current, 1N4739A has an avalanche current of 2 mW at Tamb=25°C and a max continuous forward current of 500 mA (pulse 10,000 mA). Furthermore, 1N4739A presents a breakdown voltage that is extremely stable with variations in the order of +-2%.

1N4739A is the perfect choice for applications that require stability, regulation and wide range of temperature stability. Typical applications include regulated power supply circuits, DC-DC converters, and battery chargers.

The working principle of 1N4739A can be described as follows. When the diode is forward biased and a voltage of less than 39V is applied on it, the diode operates as a normal diode, limiting the current and blocking the voltage. Once the voltage exceeds the Zener voltage the current starts flowing from anode to cathode, leading to the breakdown of the diode. This process limits the voltage across the diode and hence maintains the voltage at a constant level, giving the diode a regulating effect.