A gate driver is a power amplifier that accepts a low-power input from a controller IC and generates a high-current drive input for a high-power transistor's gates. The driver can be either an on-chip or discrete module. Gate drivers have a very important role in power electronics. They can help make a high-performance gate opener a reality. Read on to learn about the functions and benefits of these devices.
Isolated half-bridge drivers
Isolated half-bridge gate drivers are four-level, isolation-compatible devices for high-side and low-side gate drives. Their iCoupler technology offers up to 5700 VRMS of isolation. They are available in a 16 L SOIC package and support a wide range of input voltages. These devices are designed to be compatible with systems ranging from three to 5.5 V. They also operate with a wide range of logic input voltages.
A typical isolated half-bridge gate driver is based on the UCC21520 reinforced insulated gate driver. It is capable of driving both MOSFETs and SiC MOSFETs. It has a built-in isolated push-pull auxiliary power supply and has 100 kV RMS common-mode transient immunity. To drive high-voltage power MOSFETs, a typical gate driver has a TIDA-01159 reference design.
Isolated half-bridge gate drivers are also characterized by their high isolation voltages. A high isolation voltage protects against harmful current discharges and keeps the converter signals free of interference. Typical isolation voltages are expressed in terms of peak, working, and RMS isolation voltages. These measurements should be carefully considered before purchasing an isolated half-bridge gate driver. There are other considerations for selecting the best isolated half-bridge gate driver.
The MP18831 chip is a good example of an isolated half-bridge gate driver. The high power consumption of these devices makes them less suitable for industrial applications. However, they are still highly compatible with many standard microelectronic processes. The power consumption of isolated half-bridge gate drivers is twice that of their non-isolated counterparts. However, they are expensive compared to their non-isolated counterparts.
Low-side drivers
ICs for low-side gate drivers are available in several configurations. The FAN3223-25 family of low-side gate drivers is designed for N-channel enhancement-mode MOSFETs in low-side switching applications. They support both MOSFET and IGBT. The iCoupler isolation technology combined with high-speed CMOS and monolithic transformer technology allows the drivers to achieve ultra-low propagation delays and ensure the proper switching characteristics. These devices are ideal for use with synchronous rectifiers and MOSFETs and are also suitable for ground reference switching.
The switching action of MOSFETs is described in secondary synchronous rectifier circuits and pulse/gate drive transformers. The various driver solutions are discussed, including discrete and integrated designs. Current ratings of MOSFETs and discrete drivers are also discussed, along with circuits to evaluate their performance on the lab bench. These drivers are available as discrete components and as a combination of integrated PMOS/NMOS devices. The circuits and evaluations are presented with the necessary calculations.
Typical applications for low-side gate drivers include switching the output of an inverter to the ground and providing a voltage source to the load. High-side drivers also feature a floating supply for high-frequency operation. Logic inputs are compatible with standard CMOS levels, while high-side drivers feature buffers that reduce cross-conduction. A floating high-side gate is suitable for 600VDC. This driver also operates in a bootstrap configuration.
In addition to high-side switching, IR2110 Low-side gate driver IC is used for driving power MOSFETs and IGBTs. In UPS inverter circuits, they are used as high-side switches, and IR2110 is designed for high-side switching. A buck-boost DC-DC converter maintains output regulation during cold-crank events. In addition to low-side switching, IR2110 High-Low gate driver ICs are used in power MOSFETs and high-side switching applications.
Isolated high-side drivers
Isolated high-side gate drivers are a popular choice for implementing ASIL-rated applications. They protect power devices from damaging conditions such as noise and vibration. Unlike regulated supplies, isolated gate drivers use a single isolated bias supply, which provides a floating bias for the high-side gate. The isolation of isolated high-side gate drivers is a good option for systems with small sizes and low power requirements.
Half-bridge gate drivers are commonly used in many different applications and require an isolated power supply for the high-side gate drive. A typical isolated half-bridge gate driver is available in a 16L SOIC package and is composed of coreless micro-transformers that transmit gate drive signals and deliver power to the isolated high-side supply. Typical applications for isolated high-side gate drivers include industrial and medical equipment, automotive applications, and automation.
The high-side gate driver propagation-delay waveforms shown in Figures 44 to 49 are the result of a simulation using the corresponding datasheet specifications. These measurements show that the turn-on delay for each isolated high-side gate driver is 0.7 ns. Similarly, the turn-off delay varies by about 2 ns. The same thing holds for the low-side driver.
The high-side gate driver typically uses an n-channel MOSFET as its power element. These are much smaller and cheaper than p-channel devices. MOSFETs are energized by raising the gate voltage above the drain voltage, which is typically the highest voltage in the system. In some instances, a charge pump is required to boost the gate voltage. If both high-side and low-side drivers are energized, the high-side load will be permanently on.
Power MOSFETs
A Gate driver for power MOSFETs (MOSFETs with a gate resistor) is a device that controls the switching behavior of the transistors in a power circuit. The switching characteristics of a MOSFET are dependent on several parameters, including its gate resistance and source inductance. These parameters may be affected by many external parasitic components, such as a current sense resistor.
A level-shifting circuit is one such type of driver. They are commonly integrated into power-integrated circuit chips. A typical level-shifting circuit is the IR2112, sold by International Rectifier Corporation (IRC). It is a high-voltage, high-speed MOS gated power device that controls the gate of a power MOSFET or insulated-gate bipolar transistor. It has independent high and low-side output channels and logic inputs supplied by the user.
In addition to providing high-efficiency gate drivers, a new bipolar current source driver is presented. This driver eliminates the gate current diversion issue by clamping the gate voltage to a flexible negative value during the turn-off transition. The bipolar current source driver also allows the MOSFET to be turned off much faster because it can clamp the gate voltage to a more flexible negative value. This new bipolar gate driver also uses a novel DC-DC structure to enhance the overall system efficiency.
High-voltage double-diffused MOSFETs were introduced in the 1970s. They have improved continuously and now provide higher integration densities and lower capacitances. However, the two-diffused transistors are more difficult to manufacture. A double-diffused MOSFET is more expensive than a p-n junction. In a power MOSFET, the temperature coefficient is greater than that of the n-type junction.
TI Smart Gate Drivers
TI Smart Gate Drivers are designed to minimize gate dead time by using passive pulldowns to insert the optimal dead time when the FET or MOSFET is off. This feature reduces the need for external components and minimizes board space. Additionally, they have features that make them easier to use. Listed below are some benefits of TI Smart Gate Drivers. Let's explore these benefits in more detail. A Quick Overview of TI Smart Gate Drivers
The Smart Gate Driver is capable of optimizing gate drive current using the properties of the MOSFET. It can operate the driver MOSFET switch in the saturation region, which limits the current that flows to the external MOSFET. As the gate-to-source voltage plateaus in the Miller region, it can make adjustments to maintain the gate drive current. As such, Smart Gate Drivers ensure that the switch is operating in the saturation region.
TI Smart Gate Drivers offer several features to optimize performance and reduce radiated emissions. The IDrive feature allows the designer to fine-tune gate drive performance through seven levels of gate-source current. With this technology, TI Smart Gate Drivers enable designers to design flexible circuits that meet their specific needs. This technology makes the job of the designer easier by optimizing switching loss and EMI performance. It also provides extra protection features for the power MOSFET.
TI Smart Gate Drivers also include integrated VDS and VGS comparators for each output. These integrated devices manage overcurrent detection and potential gate drive faults. They are configurable via SPI and hardware settings. They also address the challenge of propagation delay optimization. So, if you are considering using TI Smart Gate Drivers in your next application, consider these features. They will make your designs more efficient and reduce costs.
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