Gate drivers are electronic circuits that apply the proper power levels to metal-oxide field-effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBTs). Gate drivers can be implemented as discrete transistors, transformers, or dedicated integrated circuits when using power-MOSFETs (IC).
They can also be built into controller integrated circuits. Partitioning the gate-drive function of controllers that use pulse width modulation (PWM) improves controller stability by removing the high peak currents and heat dissipation required to drive power-MOSFETs at extremely high frequencies.
The isolated gate drive optocouplers function as galvanic isolation amplifiers and frequently provide short-circuit protection with IGBTs. IGBTs require a continuous gate circuit to sustain gate current because of their insulated gates.
Types of Drivers
Gate drivers are classified into four types. High-side gate drivers are used to drive power-MOSFETs or IGBTs that are not ground referenced and are connected to a positive supply (floating). Low-side gate drivers, on the other hand, are used to drive power-MOSFETs and IGBTs that are connected to a negative supply.
Dual gate or half-bridge gate drivers have gates on both the low and high sides. Three-phase drivers are so-called because they are used in three-phase applications.
Three independent low-side and high-side referenced output channels are provided by these drivers. Gate drivers typically have one, two, or four output channels. Their output voltage can be inverted or uninverted.
The following are the benefits of using isolated gate drive optocouplers for IGBT/MOSFET:
- High reliability and long life
- Low system solution cost
- Ease and simplicity of design
- Variable speed/frequency capability
- Safe optical isolation (galvanic isolation)
- Regulatory and safety agency approvals
- Low power dissipation
- Small size and footprint area
Performance Specifications
- Peak output current
- Output voltage
- Fall time
- Rise time
- Supply voltage
- Power dissipation
- Propagation delay
- Switching frequency
- Operating temperature
The rise time is the amount of time required for the output voltage to increase from 10% to 90% of its maximum. In contrast, fall time is the time required for the output voltage to drop from 90% to 10% of its maximum.
Features
- Integrated protection
- Internal regulation
- Dead time control
- Input threshold
Input thresholds include transistor-transistor logic (TTL), pulse width modulation, complementary metal-oxide semiconductor (CMOS), and combinations such as TTL/PWM and TTL/CMOS.
Overvoltage protection (OVP), overvoltage protection current (OVPC), undervoltage lockout (UVLO), thermal shutdown (TSD), and overcurrent protection are examples of integrated protection types (OCP). Dead time control eliminates shoot-through currents. The output voltage level is controlled by internal regulation.
Packaging Options
- Dual in-line package (DIP)
- Small outline package (SO)
- Stretched small outline package (SSO)
- Widebody package ( 400mil DIP)
- Small outline 16pins (SO16)
- Small outline 12pins (SO12)
- Small outline 24pins (SO24)
- 15mm wide creepage package
There are also fine-pitch SO12 and SO24, one of the smallest IC packages, available. Tape reels, tubes, bulk packs, and trays or rails are some of the packing methods used for gate drivers. Commercial, industrial, and military screening levels indicate the temperature range as well as mechanical and electrical specifications.
Some of the above-mentioned isolated gate drive optocouplers are still in the works. Others are currently in full swing. Over more than 50 years, there is very little discontinued devices so isolated gate drive optocouplers are proven very reliable.
