practical solutions design with gan power...
TRANSCRIPT
GaN Systems – Confidential – 1
Practical Solutions Design With GaN Power Transistors
December 5, 2017
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Topics
• GaN increases efficiency, reduces size, weight and system cost from 20 W to 20 kW• GaN E-HEMTs use similar design techniques to what designers do today• Ecosystem of support components• Creates new topologies, enhances existing topologies• GaN E-HEMTs lowest switching losses• GaNPX® packaging allows for cost effective superior thermal solutions
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GaNPX® vs TO-247
GaN Systems - Company Overview
• Market leader for gallium nitride (GaN) power transistors• Enhancement mode devices• 100V & 650V devices.• High current devices (100V to 90A, 650V to 60A)• Industry’s most robust gate drive with +10/-20V range
• Global company with decades of GaN experience • Overnight shipping through distribution since 2014• HQ and R&D in Ottawa, Canada• Global Sales & Applications support• World-class fabless manufacturing and advanced packaging
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650 V 100 VProducts
Eval kits, reference designs & power modules
Low Resistance. Low Gate Charge. High Voltage. Very High Currents. Simple Gate Drive
GaN product portfolio
FAQs, Datasheets, CAD symbols, STEP files, Thermal models, Pspice, LTspice models, Application Notes
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EV Battery Charger
Customers have proven the value proposition
>3X loss reduction
5X sizereduction
Solarin Silicon & 2X smaller in GaN
GaNSilicon
Inverter in Silicon & 5X smaller in GaN
GaN
Silicon
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Fundamentals of GaN Systems E-HEMT
GaN Enhancement mode High Electron Mobility Transistor (E-HEMT):• Lateral 2DEG (Two-dimensional electron gas) channel formed between AlGaN and GaN layers• Positive gate bias turns on 2DEG channel• 0V or negative gate voltage shuts off 2DEG and blocks forward conduction (allows reverse conduction)• Voltage driven: Gate driver charges/discharges (CGD + CGS)• No DC gate driving current needed: gate leakage current only (IGSS)
VGS
VDS
IGSS IDS2DEG
DRAIN
GATE
CGD
CGS
CDS
SOURCE
E-HEMT circuit modelGaN E-HEMT simplified structure
Simply put –A GaN E-HEMT is
just like a MOSFET but much much faster.
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Traditional PQFN + Wire Bond
Embedded GaNPX®
Proven embedded packaging for high speed GaN device: Extremely low inductance: high frequency switching Near Chip Scale embedded Packaging No wire bonding: high reliability Lower thermal resistance RθJC
Lsource~0.4nH
Time/uSecs 20nSecs/div
3.02 3.04 3.06 3.08 3.1 3.12 3.14 3.16 3.18 3.2
Vds
_Si /
V
-0
100
200
300
400
500
GD
S
Ls = ~10-15nH
TO-247
GaNPX®
High dv/dt Low VDS overshoot Better EMI
Package is important: GaN Systems GaNPX® embedded
Benefiting from the full capability GaN requires the right package
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Driving GaN is Straightforward
650V GaN Gate driver design• Voltage driven similar to Si MOSFETs:
• +5-6V for turn-on, 0V or negative for turn-off• Maximum +7/-10V,transient +10/-20V
• High side / half bridge gate drive:• Choose driver with high CMTI (>100V/ns)• Recommend isolated DC/DC, for Bootstrap:
• Bootstrap voltage stability: post-regulation• Watch for bootstrap diode loss at higher fsw
100V GaN gate driver design• RG(on) ~= 3-6.8 Ω, minimize gate and power loop inductance• Typically use half bridge driver IC with bootstrap, 0-5/6V
+9V
0V
DB1
+6V
C1
0VGDH
CB1
R1LP2985IM5-6.1
IN OUTGND
Bootstrap post-regulation
RG,extCGD
CGS
RG,int CDSGate
Drain
Source
Simpler to drive than SiC and IGBT. Lower voltage than MOSFET to fully enhance.
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Eco System of Partnerships with Industry Leaders
Gate Drivers Magnetics
Modules
Working with GaN is mainstream
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PFC – A comparison of topologiesBoost PFC• Fixed large diode bridge loss• Challenge to achieve higher than 98% efficiency
2-phase semi-bridgeless PFC• High component count and low component utilization• Additional return diodes D3/D4• D1/D2 needs to be fast-recovery diodes• No bidirectional capability
MOSFET-based bridgeless TP PFC • DCM mode High inductor current ripple• CrCM mode Complicated control• CCM mode Reverse-recovery loss due to Qrr
GaN enables most desired PFC topology … Bridgeless Totem Pole
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Totem Pole PFC: Enabled by GaN
VAC
L1
Q1
Q2
D1
D2
CB RL
Semi-bridgeless PFC – Si MOSFET Totem Pole PFC - GaN
Part count reduced by 33%
PFC Loss Breakdown → 15% lower
The Value of GaN
BOM Cost Improvement → 15% lower
Smaller Size • Higher frequency → Smaller filters• Better topology → Fewer parts• Lower loss → Smaller heatsink
Better Efficiency• Increases from 97.5% to 99%
Eff. 97.5%
Lower System Cost• Smaller EMI filter → less expensive • Smaller heatsink → less expensive
• No parasitic BJT and Body Diode• Zero Reverse Recovery• Reverse conduction, anti-Parallel
Diode not required
GaN makes smaller, more efficient, lower cost PFC solutions possible
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LLC DC/DC Converter – GaN Based DesignThe ZVS constraints of LLC converter
A smaller Coss leads to:
GaN-based half-bridge LLC converter
𝑇𝑇𝑑𝑑𝑒𝑒𝑒𝑒𝑑𝑑 ≥ 16 × 𝐶𝐶𝑜𝑜𝑜𝑜𝑜𝑜(𝐸𝐸𝐸𝐸) × 𝐹𝐹𝑠𝑠 × 𝐿𝐿𝑚𝑚
Sufficient deadtime
Sufficient inductive energy from Lm
-
5
10
15
20
25
30
2010 2013 2016
Volu
me
(cm
3)
Magnetics volume
100 kHz
300 kHz
1 MHz
High efficiency
High power density
Resonant tank
Lm
Air gap Ptrans_loss
Irms Psw_cond
fs
Better switching characteristics of GaN improve LLC efficiency and size
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Application – Power Supply 200W AC/DC
Silicon92% efficient16.5 W losses12 W/in3
GaN96% efficient9 W losses30 W/in3
LLC
LLC
Diodebridge
Savings
PFC
PFC
System losses
4x Smaller
GaN lowers losses by > 45% and increases density by 2.5 times compared to silicon
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GaN E-HEMT Daughter Board
GaN E-HEMT X 2
Isolated Gate Driver
Same PCB layout for both boards• 2 oz. copper• 4 PCB layers• Homogeneous thermal vias
SiC MOSFET Daughter Board
Comparison GaN E-HEMT SiC MOSFETPackage GaNPX® D2PAKVDSmax 650 V 900 V
ID@25⁰C 30 A 35 ARDS(on)@25⁰C 50 mΩ 65 mΩ
VGS(op) -10/+7 V -4/+15 VCISS 260 pF 660 pFCOSS 65 pF 60 pFCRSS 2 pF 4 pFQG 5.8 nC 30.4 nCQGS 2.2 nC 7.5 nCQGD 1.8 nC 12 nCQRR 0 nC 245 nC
Let’s compare GaN to SiC
SiC MOSFET X 2
GaN and SiC boards created to exhibit same external parasitic effects
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• GaN E-HEMT (650V/50mΩ) vs SiC MOSFET (900V/65mΩ)• Switching test performed at 400V/15A half bridge hard switching double pulse test• Use same gate driver Silab Si8271 and RG(on)=10Ω, RG(OFF)=1Ω for both GaN and SiC
Switching Waveforms: GaN and SiC
GaN has 4x faster turn-on and 2x faster turn-off time than SiC MOSFET
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Eon=118.3uJ
SiC MOSFETGaN E-HEMT
400V/15A Eon measurement
Eon=41.15uJ
GaN E-HEMT
Eoff=11.02uJ
400V/15A Eoff measurement
SiC MOSFET
Eoff=33.8uJ400V/15A half bridge switching losses(Si8271GB-IS, RG(on)=10 Ω, RG(on) =2 Ω, TJ= 25°C)
Turn-on and Turn-off losses: GaN and SiC
GaN switching losses ~ 3x lower than SiC
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Lower losses benefits• Decrease heatsink size • Increase power density • Reduce operating cost• Increased lifetime
Temperature Effects: GaN and SiC
GaN has lower losses across full temperature range
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Synchronous Buck DC/DC System Efficiency and TJ400V-200V, 200kHz, Tamb = 25oC
Same layout, layers, vias, etc.
Power Loss and Junction Temperature Comparison at POUT = 900 W, fsw= 200 kHz
Efficiency and Temperature Rise: GaN and SiC
GaN increases efficiency up 1%
GaN is more than 60 °C cooler
GaN’s lower switching losses lower temp rise better, more reliable performance.
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Accelerating the Design Effort - IMS Evaluation Platform GSP65R25HB-EVB or GSP65R13HB-EVB
GaN High Power Half Bridge evaluation assembly(Gate Driver pcb + IMS HB)
IMS Half Bridge Boards(wo parallel and single transistor)
GSP65MB-EVB
High Power Full Bridge evaluation platform
mother board
Uses design concept of higher power GaN intelligent power modules (IPM).
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Thermal, Size and Layout Benefits of GaN
Optimized driver board minimizes both power and gate driver loops. Minimizes common source, power and gate driver loops
Vertical Mounting of HB IMS +Driver EVB makes good use of vertical height available in high power (> 5kW) designs.
IMS based evaluation platform augments the thermal and layout benefits of GaNPX
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GaN Systems today
Consumer
Datacenter
Industrial
Transportation
Shipping since 2014• Offices in 7 countries• Worldwide disti & direct sales
#1 in GaN• Highest current; broadest voltages• Best electrical performance• Best die & best package• Most widely used by customers
Customer successes• Solar Inverter and ESS• Motor Drives and Pumps• Wireless Power and Charging• AC Adapters• Datacenter Server and Rack Power• Automotive Onboard Charger
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GaN E-HEMTs in practical design solutions - Summary
• GaN-based power designs are more efficient, smaller, lighter • Higher efficiency (cuts losses 50-90%)• Smaller Size (reduces to 1/4 the size) – higher volumetric power densities (kW/l)• Lighter (typically 1/4 the weight) – higher gravimetric power density (kW/kg)
• Easy to use: similar drive to MOSFETs, low external parasitic effects• Enable BTP PFC topology
• No body diode Zero Reverse Recovery yet • Reverse conduction Capable anti-Parallel Diode not required
• Improve existing LLC topology • Low COSS, reduces Xformer losses, reduces rms current to reduce conduction losses
• Superior thermals: cost effective GaNPX® packaging• Lower costs: system, shipping, installation, maintenance and operating costs
PSU with Silicon
Same PSU with GaN
23www.gansystems.com • North America • Europe • Asia
Thank You for your time today …. Questions?