NXP BZV55-C4V7 Zener Diode: Key Specifications and Application Circuits
The NXP BZV55-C4V7 is a widely utilized Zener diode, part of the BZV55 series, designed for voltage regulation and protection in a multitude of electronic circuits. This small-signal diode is characterized by its precise voltage regulation at a nominal Zener voltage of 4.7 V, making it a fundamental component for stabilizing voltage levels and protecting sensitive components from overvoltage transients.
Key Specifications
The BZV55-C4V7 is housed in a compact, SOD-80 (MiniMELF) surface-mount package, ideal for high-density PCB designs. Its critical electrical parameters define its operational limits and performance:
Nominal Zener Voltage (Vz): 4.7 V at a specified test current (IZT = 5 mA).
Power Dissipation (Ptot): 500 mW at an ambient temperature of 50°C. This rating is crucial for determining the maximum current the diode can handle without damage.
Zener Impedance (ZZT): Typically 60 Ω at the test current. A lower impedance indicates better regulation performance.
Reverse Leakage Current (IR): A very small leakage current (typically < 100 nA) flows before the breakdown voltage is reached.
Temperature Coefficient: The value is approximately +2 mV/°C for this 4.7V diode, indicating how the Zener voltage varies with temperature.
Application Circuits
The primary function of the BZV55-C4V7 is to maintain a constant voltage across its terminals. Two of its most common circuit configurations are:
1. Basic Voltage Regulator:
This is the simplest application. The Zener diode is placed in reverse bias across the load (RL) it is intended to protect or power. A series current-limiting resistor (RS) is essential to control the current through the diode and drop the excess voltage from the input supply (VIN). The value of RS must be chosen carefully to ensure the Zener current (IZ) stays between its minimum knee current (IZK) and the maximum calculated from its power rating (IZmax = Ptot / Vz). The output across the load will be a stable 4.7 V, provided the input voltage is sufficiently higher than Vz and the load current is within the circuit's capability.
2. Overvoltage Protection / Clamping Circuit:
In this configuration, the BZV55-C4V7 is used to protect an input pin of an integrated circuit (IC) from voltage spikes that exceed its maximum rating. The Zener diode is connected between the signal line and ground. Under normal operating conditions (voltage below 4.7V), the diode is in its high-impedance state and does not conduct. If a voltage spike pushes the signal line above 4.7V, the diode breaks down and clamps the voltage to approximately 4.7V, shunting the excess current to ground and thereby protecting the sensitive IC. A small series resistor is often used to limit the current during a clamping event.
The NXP BZV55-C4V7 is an excellent choice for designers seeking a reliable and compact solution for low-power voltage regulation and transient protection. Its consistent performance at 4.7V makes it indispensable in power supplies, reference voltage generation, and as a safeguard for sensitive electronic components. When selecting a Zener diode, carefully considering the power dissipation and operating current range is paramount for robust circuit design.
Keywords:
Zener Diode
Voltage Regulation
Overvoltage Protection
4.7V
SOD-80
