DDZ43Q-7

The DDZ43Q-7 is a single type of zener diode, specifically developed for use in stabilising power supply voltage and to protect other semiconductor components against voltage surges. This diode is designed to maintain a low voltage drop while reliably clipping the positive and negative voltages when the zener breakdown occurs.

When the device is in forward operation, the current will increase continuously with increasing forward voltage. There is a limit to the current that can be passed through the diode, and this is specified in the device datasheet as "maximum avalanche current". It is not recommended to exceed this limit as it may damage the diode.

When the voltage reaches the zener voltage breakdown, the reverse current of the diode increases very rapidly and is then limited to a maximum value. As the reverse voltage increases, the current decreases until it reaches the zener voltage again. This is known as the "self-limiting" operation of the diode. As the voltage continues to increase further, the maximum current of the diode could increase further, but will remain below the maximum avalanche current.

The most popular application for the DDZ43Q-7 is in power supplies. It is often used to limit the input voltage to a specific level, preventing the supply from exceeding it, and ensuring that the correct output voltage is maintained. In switchmode power supplies, it is used to protect other semiconductor devices, such as transistors, by limiting any high voltage spikes that may occur. It can also be used in DC/DC converters, to regulate the output voltage, by sensing when the voltage has exceeded the zener voltage, and cutting off the output. It can also be applied to other devices, such as digital logic circuits, providing protective isolation.

The working principle of the DDZ43Q-7 is relatively simple. In forward operation, the diode behaves like any other forward biased diode, allowing current to flow through it, but with a voltage drop across it. When the voltage reaches the zener voltage, the breakdown occurs and the current is limited to the maximum avalanche current value.

The self-limiting operation of the diode is the primary factor that makes it so beneficial for power supply voltage stabilisation and protection. This is because the current does not increase above the rated value, when the voltage reaches the zener voltage. This makes it ideal for protecting other semiconductor devices, as the current can be limited to a safe level.

In conclusion, the DDZ43Q-7 is a single Zener diode, designed to stabilise power supply voltages and to protect other semiconductor components against voltage surges. The voltage passes through the diode in forward direction, but at a certain voltage breakdown, the reverse current increases sharply until it reaches the maximum avalanche current. This self-limiting operation of the diode makes it very suitable for power supply voltage stabilisation and protection applications.