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Application Notes |
iCoupler Technology Benefits Gallium Nitride (GaN) Transistors in AC/DC Designs
Highly efficient ac/dc power supplies are key to the evolution of the telecom and datacom infrastructure, as power consumption grows rapidly due to hyperscale data centers, enterprise servers, or telecom switching stations. However, the power electronics industry has reached the theoretical limit of silicon MOSFETs.
Meanwhile, recent gallium nitride (GaN) transistors have emerged as a high performance switch to replace silicon-based MOSFETs, offering increased energy conversion efficiency and enabling greater density. A new isolation concept with new specifications is required to address the advantages of the GaN transistors. GaN transistors can switch much faster than silicon MOSFETs and can achieve lower switching losses due to:
To take full advantage of a GaN transistor, the preferred requirements for isolated gate drivers are:
- Lower gate capacitance and output capacitance.
- Lower drain-source on resistor (RDS(ON)) for higher current operation, resulting in lower conduction losses.
- Low or zero reverse-recovery charge (QRR), as there is no need for a body diode.
Solution | Technology | Merits | Challenge | ADI product |
Integrated high-side and low-side driver | Level shift | Simplest single-chip solution | Large delay time, limited CMTI, external bootstrap circuit | |
Dual-isolated Integrated driver | Magnetic | Single-chip solution | Sacrifice layout flexibility, need time to charge the bootstrap cap | ADuM4223 |
Single-channel isolated driver | Magnetic | Easy for layout, high CMTI, low propagation delay/skew | Require external auxiliary power supply | ADuM3123, ADuM4121 |
Isolators and ISO power | Magnetic | Layout flexibility, easy for negative bias, no bootstrap circuit | High cost, EMI issue | ADuM110+, ADuM5020 |
- Maximum allowable gate voltage <7 V
- >100 kV/ms dv/dt at switching node, 100 kV/µs to 200 kV/µs CMTI
- High-low switch delay match ≤50 ns for 650 V application
- Negative voltage clamp (–3 V) for turning off
- Bismuth, Alain. “The Coming Hardware Revolution in Data Center Energy Efficiency.” GaN Systems, Inc., April 2020.
- “EiceDRIVER 1EDF5673K and 1EDS5663H.” Infineon Technologies AG, May 2018.
- “GN001 Application Brief: How to Drive GaN Enhancement Mode HEMT.” GaN Systems, Inc., April 2016.
- Oliver, Stephen. “GaN Power ICs: Integration Drives Performance.” Bodo’s Power Conference, Munich. Navitas, December 2017.