Other features and advancements were also included ILOAD Drain in GaNSense as system designers demanded new capabilities as they released generation after generation of GaNbased power supply products. The progression can be seen in Figure 6. At first glance, removing the shunt current sense Gate Source Mirror ISENSE ISOURCE resistor doesn't seem all that ground-breaking, but let's discuss the ripple-effects from this advancement starting with Figure 7. Any reduction or elimination of series loss elements FIG 5 Simplified diagram of Current-Sense (CS) block in GaNSense technology. Silicon FET G D S * Old, Slow Technology * High Qg * High Coss * Fsw < 100 kHz * Exposed Gate * External Gate Drive * Gate Drive Parasitics * Requires Tightly Regulated Gate-Drive Bias * External Components for Drive and Protections * dV/dt Sensitivity * Layout Sensitivity * ESD Sensitivity * Unknown Reliability * Unknown Robustness FIG 6 Evolution of GaNFast power IC. * Internal Protected Gate * Integrated Gate Drive * dV/dt Immunity * Turn-On dV/dt Control T * Layout Insensitive * 2 KV ESD Rating * Proven Reliability * Proven Robustness * 650 V Vds Continuous Rating * 800 V Vds Surge Rating * 10-24 V Vcc Bias * 5-15 V PWM Input Logic A A A Discrete GaN 800 Vmax Autonomous Standby Mode Loss-Less Current Sensing Autonomous Over-Current Protection * All GaNast Features + ... * Autonomous Standby Mode *Autonomous OverCurrent/Temperature Protections * Loss-Less Current Sensing * Ultra-Fast < 100 ns OCP * 700 V Vds Continuous Rating * 9-24 V Vcc Bias * 3.3-15 V PWM Input Logic * Removes 6.2 V Zener Diode L U 7 9 3 R 2 kV ESD helps efficiency. When comparing GaNSense technology versus an existing external series resistor sensing method (Figure 7), the total ON resistance, RON(TOT), can be substantially reduced. For a 65 W high-frequency Quasi-Resonant (HFQR) flyback circuit, for example, RON(TOT) is reduced from 340 mΩ to 170 mΩ. Even when OverTemperature Protection External Current-Sensing Resistor D G S CS RCS RCS = 170 mΩ RON (TOT) = 340 mΩ RON (TOT) = 170 mΩ FIG 7 Total on-resistance reduction through lossless sensing. 34 IEEE POWER ELECTRONICS MAGAZINE z June 2022 RDS (ON) = 170 mΩ PWM CS RSET CS S No RCS RCS = 0 mΩ D RDSON = 170 mΩ