Reference designs High frequency 3-phase GaN inverter Now that Masoud, Matt and myself have given you an overview of the these products, let’s put it all together. The TIDA-00909 and TIDA-009013 are reference designs created to show how GaN power stages, C2000 MCUs, and current sense amplifiers can be used in a very compelling design. By the way, both reference designs are actually identical hardware but one focuses on the GaN technology and the other the current sense amplifier. Of course, neither design would have been realized without the C2000 MCU LaunchPad. Please go ti.com and type in the full TIDA part numbers for more information.

48V/10A High frequency PWM 3-phase GaN inverter reference design TI Design + C2000 LaunchPad Design features Inverter w/ three 80V/10A half-bridge GaN power modules LMG5200 In-line phase current sense amplifiers INA240 with PWM rejection Interfaced with C2000 MCU LaunchPad Up to 100-kHz PWM inverter with wide input voltage range 12-60VDC Electronica Demo Design benefits Very low switching losses, efficiency up to 98.5% at 100-kHz PWM Precision current sensing with 0.1% accuracy from -25C to 85C Tested up to 100kHz PWM to drive low inductance/high-speed motors Low voltage, high-speed drives and/or low inductance brushless DC motors require higher inverter switching frequencies in the range of 40 kHz to 100 kHz to minimize losses and torque ripple in the motor. This reference design achieves this by using a 3-phase inverter with three 80V/10A half-bridge GaN power modules and precision in-line shunt-based phase current sensing for accurate control of precision drives . Gallium nitride (GaN) transistors can switch much faster than silicon FETs and integrating the GaN FET and driver in the same package reduces parasitic inductances and optimizes switching performance reducing losses, thus allowing to down-size or eliminate the heatsink. This design achieved a very impressive 98.5% peak efficiency at 100kHz PWM switching frequency. One of the largest challenges with in-line shunt-based phase current sensing is the high common-mode voltage transients during PWM switching. The INA240 bidirectional current-sense amplifier overcomes this problem using enhanced PWM rejection. The reference design offers a TI BoosterPack compatible interface to connect to a C2000 MCU LaunchPad development kit for easy performance evaluation. If you were at Electronica just a few weeks ago and made it into the TI booth, you would have noticed this reference design we’re speaking of today!

Reference design key specifications Parameter Typical value Comment DC input 48V (12-60V) 80V abs max Maximum 3-phase output current 7Arms (10A peak) per phase Power FET GaN technology LMG5200 GaN power stage PWM frequency 40kHz – 100kHz Maximum efficiency 98.5% at 100kHz PWM and 400W input power Phase current accuracy (-25°C to 85°C) ±0.5% (uncalibrated) ±0.1% (calibrated) Over nominal range ±10A One-time offset and gain calibration at 25°C PCB over-temp alert >85°C Configurable from 70°C to 85°C Interface to host processor TI BoosterPack compatible C2000 MCU LaunchPad LAUNCHXL-F28069M As mentioned previously, the design is a 48V system operating with a peak 10A current per phase. The power FETs used are the new LMG5200 power stage with GaN technology switching at a PWM frequency between 40 and 100kHz, and a peak efficiency of 98.5%. The phase current measurement accuracy is very impressive using the INA240. More on this in the next few slides. The reference design comes with a over-temperature ALERT function that notifies the processor in case the PCB exceeds 85°C. A small TMP302 temperature switch does the job here. Lastly, the board is compatible to the TI BoosterPack and utlizes the C2000 LaunchPad part listed in the table. To end this presentation, the following slides show some of the stellar results by using these three technologies.

Reference design results (phase current accuracy) System error over the entire -25°C to 85°C Phase current error (uncalibrated) ±0.5% Phase current error (calibrated) ±0.1% One-time calibration at 25°C The graph shown summarizes the accuracy of the current sense amplifier. The three plots with the greater slope represent 3 different uncalibrated temperature readings for error. This uncalibrated value is ±0.5%. Although very good performance, it is worth noting that the major impact on gain tolerance is from the 5mΩ shunt resistor used on the board. The resistance tolerance is ±1% and the temperature coefficient is 50ppm/°C, while the INA240 has a gain tolerance of 0.2% and a gain drift of 2.5ppm/°C. With just a single calibration at 25°C, the error drops down considerably to ±0.1%.

Reference design results (PWM rejection) Extremely high common-mode transients due to the LMG5200 GaN power stage at 48V/ns Settling time ~2µs  recommended blanking time of ≥2.5µs 5

Reference design results (phase current sensing) These waveforms are what the C2000 12-bit ADC sees! Hi-speed, low inductance BLDC motor typically used in drones 100kHz PWM switching frequency 2Vrms amplitude Low voltage servo motor 40kHz PWM switching frequency 2Vrms amplitude

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