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Mechanism

Vertical Double Diffused MOSFET is also called VD-MOSFET ；The distinguishing feature of VD-MOSFET is its vertical P-N junction structure, which gives it excellent voltage withstand capability and low resistance. In VD-MOSFET, charge is vertically diffused into the N-channel region and it can operate at lower drain voltages, making it an ideal choice for many high-power applications.

Main application

In addition to its high voltage withstand capability, VD-MOSFET also possesses fast switching characteristics, enabling efficient power conversion. During switching operations, VD-MOSFET can transit between high-resistance and low-resistance states in a very short time, thereby improving overall system efficiency. Furthermore, VD-MOSFET offers low static power consumption and high reliability, making it suitable for a wide range of applications.

Power Converter

Lighting Control

The main applications of VD-MOSFET include power converters, lighting control, DC motor control, electronic locks, chargers, wireless chargers, and power factor correctors. In these applications, VD-MOSFET can provide efficient power conversion and reliability while meeting the requirements for high voltage and low resistance. As a result, it finds widespread use and favor in many high-power applications.

Key parameters for MOSFET application

When using MOSFETs, it is important to consider insulation, heat dissipation, electrostatic protection, and good circuit design. In designing MOSFET circuits, factors such as input power, load, and control circuits need to be considered to ensure the proper functioning of the entire system. Additionally, it is necessary to select and configure other electronic components such as diodes and capacitors appropriately. When using MOSFETs, it is necessary to understand their important parameters, such as：

  • Absolute Maximum Ratings :

– BVDSS (Drain-Source Breakdown Voltage) : Maximum breakdown voltage between drain and source.
– VGSS (Gate-Source Voltage) : Maximum driving voltage between gate and source.
– ID(max) (Continuous Drain current (max.) : Maximum continuous drain current.
– PD (Power Dissipation) : Maximum power dissipation of the MOSFET.
– Tj (Operating Junction Temperature) : Maximum operating junction temperature of the MOSFET.

  • Electricity Characteristic :

– RDS(on) (Drain to Source on Resistance) : On-resistance of the drain-source channel.
– IDSS (Drain to Source Leakage Current) : Leakage current between drain and source.
– IGSS (Gate to Source Leakage Current) : Leakage current between gate and source.
– Vth (Gate threshold Voltage) : MOSFET turn-on voltage or gate threshold voltage.
– VSD (Diode forward voltage drop) : Parasitic diode forward voltage drop.

  • Dynamic Parameters :

– Ciss (Input Capacitance) : Input power capacitance
The total capacitance of Cgs (gate-source capacitance) and Cgd (gate-drain capacitance).
– Coss (Output Capacitance) : Output power capacitance
The total capacitance of Cds (drain-source capacitance) and Cgd (gate-drain capacitance), and it represents all the capacitance on the output power side.
– Crss (Reverse Transfer Capacitance) : Feedback capacitance
Cgd (gate-drain capacitance)

  • Transfer Switch Parameters :

– Qg (Total Gate Charge):
The amount of gate charge required for the MOSFET to transit from 0V gate voltage to a certain voltage during operation, which is charged by Ciss (input capacitance).
– Qgs (Gate to Source Charge):
The amount of charge between the gate and source needed for the gate voltage to rise from 0V to a certain voltage, charged by the gate-to-source capacitance.
– Qgd (Gate to Drain Charge):
The amount of charge between the gate and drain needed for the drain-to-source voltage (VDS) to drop from the supply voltage to the on-state voltage, charged by the gate-to-drain capacitance.
– Tr (Rising Time):
The time required for the drain-to-source voltage to decrease from 90% of the setting voltage to 10%.
– Td(on) (Turn On Delay Time):
The time from the gate-to-source voltage drops to 90% of the setting voltage to the drain-to-source voltage rises to 10% of the setting voltage.
– Tf (Falling Time):
The time required for the drain-to-source voltage to rise from 10% to 90% of the setting voltage.
– Td(off) (Turn Off Delay Time):
The time from the gate-to-source voltage drops to 90% of the setting voltage to the drain-to-source voltage rises to 10% of the setting voltage.

TVS Features

The working principle of a TVS diode is that within its normal operating voltage range, current can flow through the diode. However, when the voltage exceeds a certain threshold, it enters a low impedance state, guiding the excess current and reducing the overvoltage to a safe voltage range, thereby protecting electronic devices (e.g., ICs).

Here are its fundamental important characteristics

 

 

 

  • Fast response：

 

 

 

TVS can respond the transient voltage within nanoseconds and quickly share the overvoltage.

 

 

 

  • Low voltage leakage current：

 

 

 

TVS has very low leakage current under reverse voltage, thus not affecting the normal operation of the circuit.

 

 

 

  • High energy absorption capacity：

 

 

 

TVS can absorb high-energy transient voltage, making it suitable for various application environments.

 

 

 

  • High reliability：

 

 

 

TVS has a long lifespan, typically lasting millions of pulses, ensuring circuit stability and reliability.

Main application parameters of TVS

The selection of TVS should be based on factors such as the operating voltage, current, and protection level of the protected circuit. When choosing a TVS, it is necessary to understand the following main parameters：

  1. Reverse Working Maximum Voltage (VRWM)
  2. Reverse Breakdown Voltage (VBR)
  3. Clamping voltage (VC) at peak pulse current
  4. Reverse Current (IR)
  5. Junction capacitance (CJ), etc.

TVS Applications

TVS diodes are widely used in various electronic devices and circuits, primarily for protecting sensitive components and devices from the impact of high voltages. Here are the main applications of TVS diodes :

• Industrial and Consumer Electronics Power Protection (AC/DC) :
TVS diodes can be used to protect various types of power systems, including DC power supplies, AC power supplies, and chargers, to prevent them from being affected by high voltages.

• Communication Equipment Protection：
TVS diodes can be used to protect various types of communication equipment, including telephones, fax machines, modems, routers, etc., to prevent these devices from being affected by voltage surges from the external environment.

• Computer Equipment Protection :
TVS diodes can be used to protect computer equipment, including central processing units (CPUs), memory, hard drives, etc., from voltage surges originating from power sources or signal lines.

• Automotive Electronic Equipment Protection：
TVS diodes can be used to protect automotive electronic equipment, including engine control modules, electronic ignition systems, in-car audio systems, etc., from voltage surges originating from the vehicle’s electrical system.

• Industrial Control Equipment Protection：
TVS diodes can be used to protect various types of industrial control equipment, including programmable logic controllers (PLCs), variable frequency drivers, servo drivers, etc., from voltage surges originating from power sources or signal lines.

Zener Characteristics

Zener diode is a semiconductor diode with special voltage stabilization characteristics. Typically, a diode conducts electricity under forward bias and blocks it under reverse bias. However, a Zener diode, under specific reverse bias conditions, begins to conduct and maintain a stable reverse voltage. This stable reverse voltage is known as the Zener voltage.

Zener Key Application Parameters

When using Zener diodes, it is important to consider their maximum power rating. This is because Zener diodes generate a significant amount of heat when conducting. If the power dissipation exceeds their maximum rating, they can overheat and become damaged. When selecting Zener diodes, it is crucial to understand the following key parameters：

  1. Zener Voltage (Vz): The desired stable reverse voltage value.
  2. Zener Current (Iz): The current flowing through the Zener diode.
  3. Power Dissipation (Pd): Pd = Vz * Iz, which represents the power consumed by the Zener diode.

Zener Applications

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Mechanism

Resistor is a passive component which the main function is to limit the current in a circuit；According to Ohm’s law, the following formula：

The Main Application

Resistors are mainly used in electronic circuits.

Application principle：

When the voltage in the electronic circuit is fixed (two-pins), the design of the resistor can provide a stable current drive for the circuit and prevent damaging the circuit from excessive current；and the resistor can also be used to adjust the voltage drop in the circuit, moreover the series and parallel circuit of resistor can achieve the function of dividing voltage and current.

Voltage Divided：

As shown in the figure on the right, when the voltage value of general electrical appliances is fixed, if the fixed voltage value of the electrical appliances is lower than the power supply, it is impossible to directly connect the electrical appliances to the power supply. Therefore, in this case, usually in order to divide the voltage, a resistor with an appropriate resistance is connected in series so that the electrical appliance can operate smoothly under a fixed voltage, and the application of the resistor in it is called “voltage Divider”.

Current Divided：

As shown in the figure on the left, If it is necessary to connect some different fixed current electrical appliances to the circuit at the same time, a resistor can be connected between the two ends of the relatively low fixed current electrical appliances through parallel circuit ,this application method is called “Current Divider”.