GaN Systems GS-EVM-CHG-140WPFCQR-GS1 140W AC or DC Charger User Manual

GaN Systems GS-EVM-CHG-140WPFCQR-GS1 140W AC or DC Charger User Manual

Scope and Purpose

This document provides a comprehensive functional description and guide to the 140W AC/DC Charger design with USB PD3.1, single port type-C output charger reference design (part number: GS-EVM-CHG-140WPFCQR-GS1) based on the 650V Gallium Nitride (Gan) enhancement-mode high electron mobility transistors (e-HEMTs) from GaN Systems. It describes the system operation and covers technical aspects essential to the design process, including calculation of key components as well as additional design documents (schematics, layout, and BOM). Test results and waveforms are also included in this document.

Introduction
The 140W USB PD3.1, single port type-C Gann-based charger reference design provides a cased turn-key solution with the following key features:

• High power density of 22.8W/in3 (1.4W/cc) and high efficiency above 94.2%
• Single USB-C port
• Cost effective topologies with Totem Pole PFC+ Dual Switch QR Fullback
• Passes EN55032 Class B with >6dB margin for conduction and radiation EMI
• Meets IEC 62368-1 touch temperature requirement
• Meets IEC 61000-3-2 THD requirement with high power factor
• Output Voltage and Current: SPR: 5V3A / 9V3A / 12V3A / 15V3A / 20V5A EPR: 28V5A
• Supports most PD protocols including PD3.1, PPS, QC4.0+, BC1.2, etc.
• Comprehensive system protections such as OVP, OCP, SCP, and open loop
• Exceeds CoCr Ver5 2019/1782 efficiency standard requirement
• Fixed AC Prong

System Block Diagram

As shown in Figure 1, the reference design includes two power conversion stages: Bridgeless Totem Pole Power Factor Correction (BTP-PFC) and Dual Switch Quasi-Resonant (DS-QR) Fullback. Bridgeless topologies eliminate the diode bridge that has been widely used in conventional PFC converters. BTP-PFC has superior performance compared to conventional

PFC converters due to the high efficiency and the simple structure. The front- end BTP-PFC stage achieves high power factor and meets the IEC61000-3-2 THD standard. In addition, it maintains lower component counts, higher power density, and lower BOM cost. The second stage is the DS-QR Fullback, which provides galvanic isolation and steps down the dc bus voltage to meet the desired consumer electronics voltage. In the DS-QR Fullback converter, the overall voltage stress is divided between the two transistors, which makes it suitable for high voltage applications. In addition, the DS-QR fullback recycles the leakage energy back to the input rail. This results in removing the clamping losses. On the secondary side of the DS-QR Fullback stage, a synchronous rectifier (SR) and USB PD3.1 controller are used to achieve the various supported DC output voltages. Both PFC and DS-QR Fullback stages use two 650V, 150mΩ GaN transistor (part number: GS-065-011-1-L) for efficiency and power density improvements.
2.2. System Specifications
Table 1 summarizes the key specification and performance for this 140W GaN- based charger reference design.

Table 1. Key parameters and performance of GS-EVM-CHG-140WPFCQR-GS1 reference design

EPR: 28V5A

Max. Output Current| 5A
PD Protocols| PD3.1, PPS, QC4.0+, BC1.2 etc.
Performance| Specification
Cased Power Density| 22.8 W/in3 (1.4W/cc)
Board Dimension with Case| 60mmX60mmX28mm

(2.4inchX2.4inchX1.1inch)

Peak Efficiency| >94.2%
Average Efficiency| CoC V5 2019/1782
Standby Power| <120mW
Touch Temperature @ 28V/5A| IEC 62368-1
EMI Standard| EN55032 Class B
System Protections| OVP, OCP, SCP, Open Loop

Reference Design Board

Figure 2 shows the PCBA photo of this reference design which uses a 4-layer 2Oz FR4 PCB (1mm thickness) with common industrial components. This reference design has a mother board and two daughter boards. The daughter boards include the BTP-PFC controller and the SR controller. Figures 2a and 2b show the top- view and bottom-view of this reference design, respectively. The reference design board also includes a plastic case, copper shielding, and thermal interface material (TIM) for heat spread and EMI purposes.

Figure 2. PCBA photos for GS-EVM-CHG-140WPFCQR-GS1 reference design

GaN’s Value Propositions

GaN Systems 140W reference design has several advantages, enabled by GaN e-HEMTs, over the other adapters in the market. According to Figure 10, these include:

• ¼ the size of Si-based 140W PD3.1 chargers in the market
•  ½ the size of GaN-based PD3.1 chargers in the market
• ¾ the size of GaN-based 130W multi-output PD3.0 chargers in the market

In the following, GaN’s value in the topologies used in the 140W reference design, which are BTP-PFC and DS-QR fullback, is explained.

Figure 10. Comparison of state-of-the-art USB PD 3.x adapters in the market

GaN’s Value in BTP-PFC

BTP-PFC has been proposed before, but its application has been minimal until recently. The major challenge is the poor reverse recovery performance of conventional Si MOSFETs in the half-bridge configuration. It makes CCM operation impractical due to the excess Qtr. loss at turn-on. To avoid body diode conduction, BTP-PFC with silicon MOSFETs must work in CrCM/DCM modes, which is only suitable for lower power and has more complicated control. Usually, a multi-phase interleaved configuration is used to achieve a higher power level and increases the current ripple, which again adds cost and complexity.
Moreover, GaN e-HEMTs is an ideal solution for CCM hard switching BTP-PFC, since the absence of a body diode (zero Qtr.) and the fast-switching speed. Figure 8 shows the hard turn-on loss breakdown of Si MOSFET and GaN e-HEMTs . According to this figure, Qtr. measured using standard test methods include both Qtr. of the high side body diode and Qis of the MOSFET, though Qtr. usually dominates for Si MOSFETs. By contrast, GaN e-HEMTs exhibit significantly lower hard turn-on loss as there is only Qis loss – the loss induced at hard switching device during turn-on due to the output capacitance charging current of the free-wheeling switch. Compared to Si MOSFETs, Sic MOSFETs offer lower Qtr.. However, the Qtr. of Sic MOSFETs is highly temperature dependent. Thus, with the temperature rise, the body diode of the Sic MOSFET has increased losses.

Figure 8. Hard turn-on loss breakdown in Si MOSFET and GaN e-HEMT

Table 4 summarizes key figures of merit (FOM) between the GaN transistor and Si Super Junction (SJ) MOSFET. As can be seen, a GaN transistor has much lower FOMs compared to Si SJ MOSFETs. The combined advantages of GaN transistors: low gate charge, low parasitic capacitor, and low on-state resistance in the converter lead to a more efficient system. Accordingly, GaN e-HEMTs is also a perfect solution for high frequency Crick/ DCM BTP-PFC. To summarize GaN advantages in the BTP-PFC converter, the following benefits are highlighted:

• Highest efficiency (almost 99%)
• Highest system power density
• Highest switching frequency
• 40% fewer components
• 10-25% lower system cost
• zero Qtr. with small output charge Qis (independent of temperature)

Table 4. GaN vs Si MOSFET parameters for QR Fullback

Radom
Qg (nC)| 2| 24| 13| 16.4| Lower gate driver loss
Qgd (nC)| 0.6| 8| 4| 6| Lower switching loss
Qrr (nC)| 0| 2900| 740| 1000| Lower switching turn- on loss for PFC stage;
Package type| PDFN5X6| PDFN8X8| DPAK| TO220-FP| Smaller size

GaN’s Value in DS-QR Flyback

Even though the overall voltage stress is divided between the two transistors in DS-QR Fullback converter, it still has remarkable switching loss during high line applications. GaN e-HEMTs offer the lowest Rosson and better FOM (mentioned in previous section), which results in better the efficiency and thermal performance for DS-QR fullback. Furthermore, the switching frequency can be increased (with much lower the switching loss), which leads to major magnetics size reduction and improved power density. On the other hand, the zero-reverse recovery and optimized packaging of GaN power stage enable less EMI noise. In addition to significantly improved efficiencies, the lower switching energy of GaN transistors provides fewer thermal challenges, which is a critical advantage, especially for adapter applications.

Test Results

The section illustrates the performance test results of the charger reference design.

Test Equipment

• Oscilloscope: Tektronix MDO3054
• AC power source: Chroma 6530
• Electronic load: Chroma 6312A
• Multi-meter: UNI-T UT61E+
• Digital power meter: Hikoi PW3335

Efficiency

For the efficiency test, a PD emulator is used to simulate the Type C PD protocol. The Output voltage is directly measured by the multi-meter 34401A from USB-C port on the PCBA board and the output current is measured via the E-load 63115A. The input power is measured with the WT210.  Please note to have accurate input power, the input voltage is directly measured on the multi-meter 34401A from AC input on the PCBA when the output voltage is 15V and 20V from half load to full load.

Figure 8. The USB-C port efficiency curve at 5V, 9V, 12V, 15V, 20V and 28V

The efficiency curve in Figure 8 shows the peak efficiency is above 94.2%. The average efficiency and 10% load efficiency curves in Figure 9 show the reference design exceeds the CoCr V5 2019/1782 efficiency requirement with approximately 3% higher average efficiency over the universal input AC voltage.

Figure 9. The average efficiency and 10% load efficiency curve at 115V and 230V.

 Standby Power

In Figure 10, the no-load standby power is measured from 90V to 264V and the maximum standby power of 112mW occurs at the 264V input which meets the CoC V5 2019/1782 standard requirement with standby power less than 150mW.

Electromagnetic Interference (EMI)

The charger reference design board is measured based on EN55032 CE Class B standard for EMI conduction and EN55032 RE Class B standard for EMI radiation. The test results show that this adapter passes the EMI conduction and EMI radiation tests with at least 10dB margin and 3dB margin, respectively. Figure 9 and Figure 10 show the conduction EMI results at 230V and 115V under full load conditions (28V/5A). Moreover, Figure 11 and Figure 12 demonstrate the radiation EMI results at 230V and 115 V under full load conditions (20V/5A).

Figure 9. Conduction EMI performance at (a) 230 Vac full load Line, and (b) 230 Vac full load neutral.

Figure 10. Conduction EMI performance at (a) 115 Vac full load Line, and (b) 115 Vac full load neutral.

Figure 11. Radiation EMI performance at (a) 230 Vac full load vertical, and (b) 230 Vac Full load horizontal.

Figure 12. Radiation EMI performance at (a) 115 Vac full load vertical and (b) 115 Vac Full load horizontal.

Thermal

Figure 15 shows the construction of the internal thermal design. A plastic case with the electrical components potted in a highly conductive gel and “sandwiched” between layers of copper foil to spread the heat over the surface of the case. The surface temperature is measured at 140W output power as shown in Figure 16. The ambient temperature is approximately 25°C with the charger in operation for 20mins before the temperature is measured.

Figure 15. Surface temperature images after 1-hour continuous run at full load with 28V/5A (140W) output

The temperature results show 68°C maximum temperature for 140W at 25°C ambient temperature. The results meet the IEC 62368-1 requirement for touch temperature.

Electrical Waveforms

Figure 17 shows the PFC stage full load steady state waveforms at different input AC voltage.

• Figure 17. BTP-PFC stage switching waveforms at different input voltages and full load (VPFC_SW: Vds voltage of GaN)
• Figure 18 shows the DS-QR flyback dual switch steady state waveforms at different loads. The maximum frequency occurs at full load, which is approximately 150KHz at high line 264V input. Moreover, Figure 19 shows the synchronous rectification waveforms of the DS-QR flyback.
• Figures 22 shows the output voltage is adjusted by the PD simulator; the Vds waveform is smooth when PD voltage is changed. When output PD voltage is changed from 5V to 9V at 3A, the PFC is turned on with the output power beyond 25W.
• Figure 23 gives the output ripple voltage waveform with different output PD voltage. The output ripple voltage is below 430mV at different output PD voltages of 5V, 9V, 12V, 15V, 20V and 28V.

Figure 18. DS-QR flyback primary steady state waveforms at different loads (VSW1: Vds voltage of high-side GaN; VSW2: Vds voltage of low-side GaN )

Figure 19. DS-QR flyback secondary side synchronous rectification waveforms under different loads (VDS_SR:
Vds voltage on SR; VGS_SR: gate to source voltage of SR)

Figure 22. The output voltage is adjusted by the PD simulator with different PD output voltage
(VSW2: Vds voltage for QR’s GaN; Vo: USB-C output voltage)

Figure 23. Output voltage ripple with different voltage and full load (Vo: USB-C output voltage)

Conclusion

The 140W USB PD3.1, single port type-C GaN-based charger reference design is introduced in this technical manual. The reference design achieves the following best-in-class features and performance:

• Topology: Cost Effective Totem Pole PFC+ DS-QR Flyback
• Cased Power density: 22.8W/in3 (1.4W/cc)
• Efficiency:>94.2%
• Standby power: Exceeds standards with <150mW
• Waveforms: Clean with full protections (SCP, OCP, OVP etc.)
• Thermal: Case temperature < 73.1°C (meet IEC 62368-1 touch temperature)
• EMI: Pass EN55032 Class B with >6dB margin

References

1. GaN Systems Application Note GN010, EZD rive TM Solution for GaN Systems E-HEMTs, 2020,[Online]. Available: https://[gansystems.com/wp-content/uploads/2020/07/GN010_EZDrive-Solution-for-GaN-Systems-GaN-Transistors-_20200715.pdf](http://gansystems.com/wp-content/uploads/2020/07/GN010_EZDrive-Solution-for-GaN-Systems-GaN-Transistors-_20200715.pdf)
2. GaN Systems Reference Design, GS-EVM-CHG-65WQR-GS1, 65W Type-C PD QR Charger Reference Design [Online]. Available: https://gansystems.com/evaluation-boards/gs-evm-chg-65wqr-gs1/
3. GaN Systems Reference Design, GS-EVM-CHG-100WQR-GS1, 100W PFC + QR Type-C USB PD 2C port Charger Reference Design [Online]. Available: https://[gansystems.com/evaluation-boards/gs-evm-chg-100wpfcqr-gs1/](http://gansystems.com/evaluation-boards/gs-evm-chg-100wpfcqr-gs1/)
4. GaN Systems Reference Design, GS-EVM-CHG-250WPFCLLC-GS1, 250W AC/DC Charger PFC & LLC reference design [Online]. Available: https://[gansystems.com/evaluation-boards/GS-EVM-CHG-250WPFCLLC-GS1/](http://gansystems.com/evaluation-boards/GS-EVM-CHG-250WPFCLLC-GS1/)
5. GaN Systems Reference Design, GS-EVM-BTP-3kW-GS, 23kW High-Efficiency CCM Bridgeless Totem Pole PFC Reference Design using GaN E-HEMTs [Online]. Available: https://[gansystems.com/evaluation-boards/gs-evb-btp-3kw-gs/](http://gansystems.com/evaluation-boards/gs-evb-btp-3kw-gs/)

Reference Design Important Notice
GaN Systems Inc. (GaN Systems) provides the enclosed reference design under the following AS IS conditions: This reference design is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, and OR EVALUATION PURPOSES ONLY and is not considered by GaN Systems to be the design of a finished end-product fit for general consumer use. As such, the reference design provided is not intended to be complete in terms of required design, marketing, and/or manufacturing-related protective considerations, including but not limited to product safety and environmental measures typically found in end products that incorporate such semiconductor components or circuit boards. This reference design does not fall within the scope of the European Union directives regarding electromagnetic compatibility, restricted substances (RoHS), recycling (WEEE), FCC, CE or UL, and therefore may not meet the technical requirements of these directives, or other related regulations. No License is granted under any patent right or other intellectual property right of GaN Systems whatsoever. GaN Systems assumes no liability for applications assistance, customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.

• In Canada: GaN Systems Inc. 770 Palladium Drive, Suite 201 Ottawa, Ontario, Canada K2V 1C8 T +1 613-686-1996
• In Europe: GaN Systems Ltd., German Branch Terminal Strasse Mitte 18, 85356 München, Germany T +49 (0) 8165 9822 7260
• In the United States: GaN Systems Corp. 2723 South State Street, Suite 150, Ann Arbor, MI. USA 48104 T +1 248-609-7643

Important Notice – Unless expressly approved in writing by an authorized representative of GaN Systems, GaN Systems components are not designed, authorized or warranted for use in lifesaving, life sustaining, military, aircraft, or space applications, nor in products or systems where failure or malfunction may result in personal injury, death, or property or environmental damage. The information given in this document shall not in any event be regarded as a guarantee of performance. GaN Systems hereby disclaims any or all warranties and liabilities of any kind, including but not limited to warranties of non-infringement of intellectual property rights. All other brand and product names are trademarks or registered trademarks of their respective owners. Information provided herein is intended as a guide only and is subject to change without notice. The information contained herein or any use of such information does not grant, explicitly, or implicitly, to any party any patent rights, licenses, or any other intellectual property rights. General Sales and Terms Conditions apply. © 2009-2022 GaN Systems Inc. All rights reserved.

References

• GaN Systems
• GaN Systems
• GS-EVB-BTP-3KW-GS Evaluation Board | GaN Systems
• GS-EVM-CHG-100WPFCQR-GS1 Evaluation Board | GaN Systems
• GS-EVM-CHG-100WPFCQR-GS1 Evaluation Board | GaN Systems
• GS-EVM-CHG-250WPFCLLC-GS1 Evaluation Board | GaN Systems
• GS-EVM-CHG-65WQR-GS1 Evaluation Board | GaN Systems

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