Gate Drivers

Gate drivers are electronic circuits that apply correct power levels to metal-oxide field-effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBTs). With power-MOSFETs, gate drivers can be implemented as transformers, discrete transistors, or dedicated integrated circuits (IC). They can also be integrated within controller ICs. Partitioning the gate-drive function of controllers that use pulse width modulation (PWM) improves controller stability by eliminating the high peak currents and heat dissipation needed to drive power-MOSFETs at very high frequencies. With IGBTs, gate drivers serve as isolation amplifiers and often provide short-circuit protection. Because of their insulated gates, IGBTs require a continuous gate circuit in order to sustain gate current. 

There are four basic types of gate drivers. High-side gate drivers are used to drive power-MOSFETs or IGBTs that are connected to a positive supply and not ground referenced (floating). Conversely, low-side gate drivers are used to drive power-MOSFETs and IGBTs that are connected to a negative supply. Dual gate or half-bridge gate drivers have both low-side and high-side gates. Three-phase drivers derive their name from the fact that they are used in three-phase applications. These drivers have three independent low-side and high-side referenced output channels. Typically, gate drivers have 1, 2, or 4 output channels. Their output voltage can be either inverted or non-inverted.  

Gate drivers vary in terms of performance specifications and features. Performance specifications include output voltage, peak output current, supply voltage, rise time, fall time, propagation delay, power dissipation, switching frequency, and operating temperature. Rise time is the time needed for the output voltage to increase from 10% to 90% of maximum. Conversely, fall time is the time needed for the output voltage to decrease from 90% to 10% of the maximum. Features for gate drivers include input threshold, integrated protection, dead time control and internal regulation. Input thresholds consist of transistor-transistor logic (TTL), complementary metal-oxide semiconductor (CMOS), pulse width modulation, and combinations such as TTL/CMOS and TTL/PWM. Integrated protection types include over-voltage protection (OVP), over-voltage protection current (OVPC), undervoltage lockout (UVLO), thermal shutdown (TSD), and over-current protection (OCP). Dead time control eliminates shoot-through currents. Internal regulation controls the level of the output voltage. 

Gate drivers are available in a variety of IC packages. Basic types include ball-grid array (BGA), chip scale package (CSP), quad flat package (QFP), small outline package (SOP), single in-line package (SIP) and dual in-line package (DIP). Fine-pitch land grid array (FLGA) and SC-70, one of the smallest IC packages, are also available. Packing methods for gate drivers include tape reels, tubes, bulk packs, and trays or rails. Screening levels such as commercial, industrial, and military indicate the supported temperature range as well as mechanical and electrical specifications. Some listed gate drivers are still in development. Others are in full production. Devices that are discontinued are no longer available from the manufacturer, but may still be found in the supply chain.

• Using NEC Optocouplers as Gate Drivers in IGBT and Power MOSFET Applications
  Reviews the characteristics and technical requirements of using an NEC high speed optocoupler to gate drive an IGBT or Power MOSFET....
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• Optocoupler Performance Comparison: NEC PS9552 vs. Avago HCPL-3120
  Both the PS9552 and HCPL-3120 are optically-coupled isolators that employ a GaAlAs LED on the input side and a photo diode, a signal processing circuit, and a power output transistor on the output...
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• Determining MOSFET Driver Needs for Motor Drive Applications
  Electronic motor control for various types of motors represents one of the main applications for MOSFET drivers today. This application note discusses some of the fundamental concepts needed to obtain...
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Part Numbers for Gate Drivers