Power MOSFET is the most common power semiconductor, mainly because its gate drive requires low power and fast switching speed, making it the most commonly used power semiconductor when driving a motor. This article will show you the technical characteristics of power MOSFET and the product characteristics of NTBLS1D5N10MC power MOSFET introduced by onsemi.
MOSFET and IGBT have their advantages
The power semiconductor is the core of power conversion and circuit control in electronic devices. It is mainly used to change the voltage and frequency in electronic devices, as well as to perform functions such as DC and AC conversion. As long as in a circuit system with current, voltage and phase conversion, power components will be used. Basically, power semiconductors are roughly divided into two categories: power discrete devices and power integrated circuits. Among them, power discrete device products include MOSFET, diode, and IGBT, among which MOSFET and IGBT are the most important.
In the low current region, the turn-on voltage of MOSFET is lower than that of IGBT, while in the high current region, the turn-on voltage of IGBT is lower than that of MOSFET. Especially under high temperature conditions, this phenomenon is especially obvious. IGBT is usually used at a switching frequency lower than 20kHz because its switching loss is greater than that of a unipolar MOSFET. The advantage of MOSFET is that it can be applied to high frequency fields. MOSFET operating frequency can be applied to radio frequency products from several hundred KHz to tens of MHz, while IGBT reaching 100KHz is almost the best operating limit.
MOSFET has the advantages of high input impedance, low driving power, fast switching speed, no secondary breakdown, wide safe working area, good thermal stability, etc. Generally speaking, MOSFET is suitable for portable rechargeable batteries or mobile devices. As for IGBT, it is suitable for high voltage and high power equipment, such as motors, automobile power batteries, etc.
N-channel power MOSFET has lower on-resistance and smaller size
With the continuous evolution of MOSFET and CMOS technology, integrated circuits have developed rapidly since 1960, which is also the reason why the design of power MOSFET can be realized. The advantages of power MOSFET are its fast switching speed, high efficiency at low voltage, easy-to-implement parallel technology, high bandwidth, robustness, simple bias, easy use and easy maintenance. Power MOSFETs can be used in many different fields, including most power supplies, DC-DC converters, low voltage motor controllers, etc., as well as many other applications.
Power MOSFETs can be divided into P-channel and N-channel depending on conductive channels. Due to the low on-resistance (RDS(on)) and small size of N-channel MOSFETs, the selectivity of N-channel MOSFETs in product applications exceeds that of P-channel. Synchronous rectifier applications almost always use N-channel technology, mainly because the RDS(on) of the N-channel is smaller than the P-channel and it can be turned on by applying a positive voltage to the gate.
Power MOSFETs are mostly carrier devices. N-channel MOSFETs have electrons flowing during conduction, and P-channel MOSFETs use positive charges called holes during conduction. The fluidity of electrons is three times that of holes. Although there is no direct correlation, in the case of RDS(on), in order to obtain equal values, the die size of the P-channel is about three times that of the N-channel, so the die size of the N-channel is smaller.
MOSFET driver for motor drive
In motor drive systems, gate drivers or "pre-driver" ICs are often used with N-channel power MOSFETs to provide the high current required to drive the motor. There are many design factors to consider when selecting driver IC, MOSFET and related passive components used in some cases.
If you want to design a driver for a DC motor (whether brush motor or a three-phase brushless motor), you should determine the design details of the driver from the characteristics of the motor. The two main factors are the working voltage and current requirements of the motor. In general, the motor has a given rated voltage and rated current, but in actual operation, these values may be different from the rated value. The actual speed of the motor depends on the applied voltage, and the current required by the motor depends on the applied torque. Therefore, the driver design does not necessarily need to fully meet the specifications of the motor.
In order to ensure that the rated value of the selected power MOSFET is at least equal to the power supply voltage and maximum current required by the motor, it is even better to leave a certain margin to ensure the best performance. Generally, the drain-source voltage rating (VDS) of MOSFET should be at least 20% higher than the power supply voltage. In some cases, especially in systems with large current, large torque step size and poor power supply control, the rated current of MOSFET must be high enough to provide the peak current required by the motor.
In addition, heat dissipation is also the focus in selection of MOSFET. MOSFET dissipation power will generate heat in drain-source resistance RDS(ON). Thermal conditions including ambient temperature and MOSFET heat dissipation determine the power that can be dissipated, while the maximum allowable power consumption is finally determined based on the RDS(ON) value of MOSFET. In addition, the total gate charge (QG) needs to be considered. The gate charge is used to measure the amount of charge required to turn on and turn off the MOSFET. MOSFET with lower QG is easier to drive. Compared with MOSFET with higher QG, it can switch faster with lower gate drive current.
Excellent power MOSFET characteristics meet application requirements
onsemi is a leader in the industry in the field of power MOSFET, and has introduced various specifications of power MOSFET for different application requirements, including N-channel, P-channel and complementary MOSFET for power conversion and switching circuits.
The NTBLS1D5N10MC introduced here is a single, N-channel power MOSFET, supports TOLL package, can output 100V, 1.53 mΩ, 298 A power, has low RDS(ON), low total gate charge (QG) and capacitance, and has low switching noise/electromagnetic interference (EMI). It is a Pb-free, halogen-free/brominated flame retardant (BFR) device, and is RoHS compliant, which can minimize conduction loss and minimize drive loss. It can be applied to power tools, battery-powered vacuum cleaners, UAVs/drone, material handling, battery management systems (BMS)/storage, home automation, etc. Common end products include motor control, industrial power supplies and solar inverters, etc.
Conclusion
Motor drive applications are extensive, among which, power MOSFET plays an important role. onsemi has a variety of power MOSFET product lines. Among them, NTBLS1D5N10MC unipolar and N-channel power MOSFET can meet the demanding requirements of related applications and is one of the best choices for motor drive control.