BZX79C39

Diodes - Zener - Single

BZX79C39 is a type of diode that specifically conforms to the Zener standard. It is a single diode that can withstand voltage up to 39V. As with all other diodes, its polarity is important and a reverse bias connection could damage the diode, resulting in its complete breakdown. This makes it indispensable in preventing excessive sudden power surges and spikes, which could potentially damage an electrical system or device.

Application Field

BZX79C39 is commonly used for protection against electrical overvoltages, eliminating damaging surges and spikes of higher-than-expected voltages. Some specific functions include the following:

• Wireless signal conditioning
• Flow signal conditioning and isolation
• Controlling AC noise signals
• Limiting power outputs in power plants
• Surge and spike protection
• AC voltage regulation

Working Principle

The main purpose of BZX79C39 is to reduce the voltage across a circuit by allowing current to pass in the reverse direction in instances of an overvoltage event.

BZX79C39 has two pn junctions: one forward-biased and one reverse-biased. Under normal circumstances, the voltage across a junction is near zero due to the opposing electric fields created by the positive and negative charges. In a reverse-biased junction, the electric fields are in the same direction, thus a voltage difference exists.

When a high voltage surge is applied to the diode, it allows the electric fields to move in opposite directions, creating a tunnel effect for the current to travel through. The current then passes in a reverse direction resulting in a lower voltage across the junction.

The BZX79C39 is engineered to have a high junction potential, at 39V max, in order to allow enough current flow during an overvoltage event while still being able to regulate the voltage. The effectiveness of this adjustment is determined by the size of the junction capacitance and the voltage drops.