Benefits & Advantages
of a GaN-based
3kW AC/DC PSU
Stephen Coates
GM (Asia) & VP Global Ops
March 2022
1
Outline
• Datacenter Power Architecture and Trends
• Power Factor Correction
• LLC Resonant Converter
• GaN based 3kW AC/DC PSU
• Summary
22
Electronics innovation across all markets
Result is exponential growth in compute and data
3
2X
CPU
2X
GPU
28X
Memory
Performance Increase
Hardware Action
Higher Performance Leads to Higher Power Consumption
71%
Increase !
50%
Increase !
67%
Increase !
Power Consumption (normalized)
Baseline system performance
Higher system performance
Power Supplies must be highly efficient, small size and high power
Source: QCT internal study
4
Datacenter Power Architecture
UPS
230
Vac
480Vac
4160Vac
AC/DC
PSU
PDU
DC/AC
PFC
12V
DC/DC
60HZ
Transformer
4160Vac
480Vac
60HZ
Transformer
230
Vac
PFC
VR
CPU
POL
Memory
POL
Chipset
Motherboard
PSU
PDU
Motherboard
48V
DC/DC
Bidirectional
DC/DC
VR
CPU
POL
Memory
POL
Chipset
Benefits of GaN in AC/DC PSU Design:
• Highest efficiency
• Smallest size
• Highest Power Density
• Lowest cost $/Density
5
PSU Trends
Efficiency
• Platinum  Titanium  Titanium+
• TCO Reduction with energy saving
• Opportunity to reduce 13% ($M)
Power Density ($ per Density)
• Power: 2kW  2.6kW  3.2kW
• 40W/in3  80W/in3, ideally 100W/in3
• 2X space for data processing servers,
add 5G RAM ($2000 value)
6
Power Supplies
10
Power Supplies
34
Servers
30
Servers
66
Power Factor Correction (PFC)
77
Evolution of PFC Topology
Interleaved Bridge Diode
Boost PFC
2000’s
Bridge diode Boost PFC
1990’s
AC
AC
CCM
D1
AC
CrM
D2
L1
Cbus
L2
Interleaved
Da
Db
Q1
Q2
Bridgeless Totem Pole PFC
Now
① Interleaved CrM
IL1
AC IN
Semi-Bridgeless Boost PFC
2000’s
Q1
Q3
2010’s
Q5
L1
L2
IL2
Q2
Active Bridge
Cbus
Q4
Q6
AC IN
L1
IL
Q3
IL
Cbus
VgsQ2
Q2
Q4
VgsQ4
D1
L1
② CCM with GaN or SiC
Q1
Active Bridge Boost PFC
Cbus
AC
Q1
VgsQ4
VgsQ2
Bridgeless Totem Pole PFC is the latest technology for high efficiency PFC
8
3kW PSU PFC Loss and Efficiency Comparisons
Bridge diode Boost PFC
（CCM）
Topology
(a) Positive half-cycle:
t=D
Active Bridge Boost PFC
（CCM）
D1
D1
AC IN
+AC IN
Cbus
Cbus
-
Q1
Conducted devices:
(b) Positive AC half-cycle:
t = (1-D)
Cbus
-
+
AC IN
Cbus
-
Q1
Power Loss (W)
&
Peak Efficiency
@50% Loading
20.00
15.00
Q1
2pcs BR diode+1pcs SiC diode
2pcs Si MOS+1pcs SiC diode
97.3%
98.3%
AC IN
Q3
L1
Cbus
Cbus
-
Q1
+
Q1
+ AC IN
Q4
Q6
Q2
1pcs Si MOS+2pcs SJMOS (ZCS)
L1
AC IN
Bridgeless Totem Pole
（CCM）
Q5
L2
-
D1
L1
Q3
L1
Q2
2pcs Si MOS+1pcs SJMOS
D1
+
AC IN
Q1
2pcs BR diode+1pcs SJMOS
Conducted devices:
Q1
+
L1
L1
+
Interleaved CrM Totem Pole
(CrM)
Q3
Q5
Cbus
L2
Q2
Q4
Q1
+ AC IN
L1
Q4
1pcs Si MOS+1pcs GaN
Q3
L1
Cbus
Q2
Q6
1pcs Si MOS+2pcs SJMOS (ZVS)
Q4
1pcs Si MOS+1pcs GaN
98.8%
98.5%
10.00
5.00
0.00
Line Frequency Device
Fast Switching Device
HF GaN or MOSFET
LF MOSFET
Boost Diode
Bridge Rectifier diode
Active Bridge diode
PFC inductors
Input EMI filter
GaN Bridgeless Totem Pole has lowest loss and highest efficiency
9
3kW PSU PFC Topology Summary
Topology
Bridge diode Boost PFC
Interleaved Bridge Diode Semi-Bridgeless Boost PFC Active Bridge Boost PFC Interleaved CrM Totem Pole
Boost PFC
D1
D1
L1
D1
D2
Cbus
AC IN
Cbus
Cbus
AC IN
Cbus
Q3
Q5
Q1
Q3
AC IN
L1
Cbus
L2
L1
Cbus
L2
L2
Q1
Q1
AC IN
L1
L1
L1
AC IN
D1
D2
AC IN
Bridgeless Totem Pole
Q1
Q2
Da
Db
Q1
Q2
Q1
Q2
Q4
Q6
Q2
Q4
Mode
CCM
CCM
CCM
CCM
CrM
CrM or CCM
Transis
tors
Si SJMOSFET
Si SJMOSFET
Si SJMOSFET
Si SJMOSFET
Si SJMOSFET
GaN HEMT or SiC MOSFET
Fsw
<100KHz
<100KHz
<100KHz
<100KHz
<200KHz
CrM: to 1MHz;
CCM to 500KHZ
Peak
Eff.
97.3%
97.5%
98.3%
98.3%
98.5%
98.8%
Cost
Low
Low
Highest
High
Highest
Med-Low
EMI
Pros
• Less ripple current
• Very straightforward
• Well-known technology • Very straightforward
• Well-known technology
• Many types of
• Simple bridgeless PFC
• Good efficiency above
98%
• High efficiency
• Low Efficiency
• Low power density
• High BOM cost (2x) and
big size
• Complicated voltage/
current sensing circuit
• High CM noise if no
Da/Db
• High BOM cost for active • High peak current with
controllers
Cons
Line Frequency Device
Fast Switching Device
• Many types of controllers
• Low Efficiency
• Low power density
bridge (MOS and drive
controller)
• ZCS with soft-switching
• Higher eff. than Booster
• Interleaved ripple
cancellation
limited output power,
normally <1.5KW
• Complicated on current
sense and control&drive
• Highest efficiency
• Zero Qrr for GaN
• Highest Power density
• Zero current detect and
new algorithm for low
THD improvement
• Hard switching with
WBG devices
10
3kW PSU PFC for 80+ Titanium
Bridge diode Boost PFC
Interleaved Bridge Diode Semi-Bridgeless Boost PFC Active Bridge Boost PFC Interleaved CrM Totem Pole
Boost PFC
GaN-based Bridgeless Totem Pole achieves
80+ Titanium goal
Topolo
gy
D1
D1
L1
AC IN
Cbus
D1
D2
L1
AC IN
Q1
AC IN
L1
L1
Cbus
Cbus
AC IN
Cbus
Q3
Q5
Q1
L2
Q3
AC IN
L1
Cbus
L1
Cbus
L2
L2
Q1
D1
D2
AC IN
Bridgeless Totem Pole
Q1
Q2
Da
Db
Q1
Q2
Q1
Q2
Q4
Q6
Q2
Q4
Modes
CCM
CCM
CCM
CCM
CrM
CrM or CCM
Transis
tors
Si SJMOSFET
Si SJMOSFET
Si SJMOSFET
Si SJMOSFET
Si SJMOSFET
GaN HEMT or SiC MOSFET
<100KHz
<100KHz
<100KHz
<100KHz
<200KHz
CrM: to 1MHz;
CCM to 500KHZ
Peak
Eff.
97.3%
97.5%
98.3%
98.3%
98.5%
98.8%
Cost
Low
Low
Highest
High
Highest
Med-Low
Fsw
EMI
Pros
Cons
•
•
•
Very straightforward
Must replace
Well-known
diodes with
technology
transistors, Active
of
• Many
Bridgetypes
to achieve
controllers
Titanium+
• Less ripple current
• Simple bridgeless PFC
• Must replace diodes
• x2 BOM Cost
• Very straightforward
• Good
efficiency above
with transistors,
• Low power density
• Well-known
technology
98%
Active Bridge to
• Many
typesTitanium+
of controllers
achieve
efficiency above
• • High
High BOM cost
• Low Efficiency
• Low power density
• Low Efficiency
• Low power density
• High BOM cost for
Line Frequency Device
Fast Switching Device
• High BOM cost (2x) and
big size
• Complicated voltage/
current sensing circuit
• High CM noise if no
98.3%
• ZCS
with soft-switching
• 2xchannel design
• Higher
Booster
with eff.
highthan
BOM
cost
• Interleaved
ripple
• Complicated on
cancellation
current sense and
• Highest efficiency
• Zero Qrr for GaN
• Highest Power density
control & drive
active bridge (MOS and
drive controller)
• High peak current with
• Zero current detect and
limited output power,
new algorithm for low
normally <1.5KW
THD improvement
• Complicated on current • Hard switching with WBG
sense and control&drive devices
11
3kW PFC PSU Summary
Bridge diode Boost PFC
Interleaved Bridge Diode Semi-Bridgeless Boost PFC Active Bridge Boost PFC Interleaved CrM Totem Pole
Boost PFC
D1
D1
Topolo
gy
D1
L1
AC IN
Cbus
D1
D2
Cbus
Cbus
AC IN
Cbus
Q3
Q5
Q1
Q3
AC IN
L1
L1
Cbus
L2
Cbus
L2
L2
Q1
AC IN
L1
L1
L1
AC IN
Q1
D2
AC IN
Bridgeless Totem Pole
Q1
Da
Q2
Db
Q1
Q2
Q1
Q2
Q4
Q6
Q2
Q4
EffPK
97.3%
97.5%
98.3%
98.3%
98.5%
98.8%
Cost
Not applicable
Not applicable
117%
100%
116%
91%
80+
No Titanium
No Titanium
Titanium
Titanium
Titanium+
Titanium++
• Must replace diodes
with transistors, Active
Bridge, to achieve
Titanium+
• Must replace diodes with • x2 BOM Cost
transistors, Active Bridge, • Low power density
to achieve Titanium+
• High BOM cost
• Peak current limited to
1.5kW
• High BoM cost and
complicated
• BTP-PFC with GaN
• Highest efficiency
• Lowest $/Density to
achieve Titanium+
GaN-based BTP-PFC for Titanium
• Highest efficiency, near 99%
• 40% fewer components
• 10%~25% lower system cost
Line Frequency Device
Fast Switching Device
12
Why GaN for Bridgeless Totem Pole PFC? (#1)
GaN HEMT
Si MOSFET
Hard-switching transition of GaN E-HEMT
Qrr and Qoss loss for MOSFET
Qoss loss for GaN
GaN transistor:
•
No Qrr loss-> high efficiency
•
No Qrr period-> high switching frequency
13
Why GaN for Bridgeless Totem Pole PFC? (#2)
SiC MOSFET
GaN HEMT
GaN transistor:
Q1
Q3
Q1
AC IN
Q3
AC IN
L1
Cbus
Q2
Q4
Q2
Reverse Characteristics @ Tc=25°C
GaN HEMT
GaN HEMT 650V/15A
Cbus
SiC MOSFET 650V/120mΩ
Small output charge from
parasitic capacitance
•
Zero reverse recovery
charge, Qrr=0, without
temperature dependency
Q4
Reverse Characteristics @ Tc=100°C
GaN HEMT
Si MOSFET 650V/15A
Reverse Charger Qrr/Qoss
(nC)
L1
•
Qrr/Qoss @400V/15A
250
SiC MOSFET
GaN HEMT
200
150
100
50
0
Si diode 650V/15A
25degC
100degC
Temperature °C
14
3kW Bridgeless Totem Pole PFC (GS-EVB-BTP-3KW-GS)
Main Specifications:
•
•
•
•
•
•
•
Input Voltage range:
Output Power:
Output Voltage:
Switching frequency:
Peak efficiency:
PCBA board size:
Power Density:
AC IN
90V~264Vac
3W (low line 1.5kW)
400V
65KHz
>98.8%
126mm*124mm*40mm (air-forced cooling)
78W/inch3 (air-forced cooling)
Q1
Q3
L1
Cbus
Q2
Q4
GaN Systems Parts:
• GS-065-030-2-L (650V 50mΩ GaN)
End Applications:
• Datacenter/Server Power Converter
• Telecom SMPS
• Industrial SMPS
GaN-based Bridgeless Totem Pole achieves 98.8% efficiency and <60°C
15
LLC Resonant Converter
16
16
LLC Operation Mode and Loss Analysis
dead time
Q1
IDS,L
Q2
Cr
n:1:1
Lr
Lm
ILm
ILm
Low Side (LS) GaN
+
-
+
-
LS GaN ON
LS GaN OFF
3rd quadrant operation 3rd quadrant operation
④
⑤
⑥
+
-
+
-
+
LS GaN OFF
Capacitor discharge
③
②
+
-
①
LS GaN ON
On-state operation
LS GaN OFF
Capacitor charge
LS GaN OFF
Vds=Vin
+
Vin
-
(Circulating)
Reverse conduction and turn-off losses can not be ignored
Reverse
Turn-off loss
Conduction
loss
ZVS achieved
for high
frequency
LLC topology
Conduction loss
17
GaN value for LLC Topology (#1)
Ilm_pk
ILr
ILm
charge
Q1
Vin
t
Vds
Vin
discharge
Ilm−pk Vin
=
Lm �
t
2
t=Ts/4, Ts=1/fs
Ilm−pk
Vin � Ts
=
8 � Lm
Ilm−pk
2 � Co(tr) � Vin
=
tdead
Minimum dead time:
𝐭𝐭 𝐝𝐝𝐝𝐝𝐝𝐝𝐝𝐝𝐦𝐦𝐦𝐦𝐦𝐦 = 𝟏𝟏𝟏𝟏 � 𝑪𝑪𝑪𝑪(𝒕𝒕𝒕𝒕) � 𝑳𝑳𝒎𝒎·fs
Parameters
Lm
Q2
ILm
Si/SiC
GaN
② if same Lm and tdead
③ if same fs and Lm
Note: Co(tr) -Effective Output Capacitance, time related
Reference: GaN Webinar Playback - GaN Performance Advantage in Totem Pole PFC and LLC
Converters | GaN Systems
GaN
Value Proposition
Much lower Co(tr)
Co(tr)
① if same fs and tdead
Vo
n:1:1
Lr
ILr
Ilm_pk
tdead
2 � Co(tr) · Vin = Ilm−pk � tdead
Cr
1
Lm∝ 𝐶𝐶𝐶𝐶(𝑡𝑡𝑡𝑡)
1
fs∝ 𝐶𝐶𝐶𝐶(𝑡𝑡𝑡𝑡)
tdead∝ Co(𝑡𝑡𝑡𝑡)
Lm
fs
tdead
ƞ
w/m3
ƞ
GaN-based LLC
• High frequency >200KHz for high density
• High efficiency for both light load and full load
18
GaN value for LLC Topology (#2)
Vp
Q1
Cr
n:1:1
Lr
Lm
Q2
Vo/Vin
GaN-based LLC
Ip
 fsw=fr, peak efficiency achieved
Normalized
frequency
Normalized
Frequency
Vp
Dead time circulating
loss
 Efficiency is dominated by Rdson
Hard switching turn-off
at high frequency
Vp
Ip
Ip
 fsw<fr, output voltage step up
•
fsw>fr, output step down
 Large primary circulating current (GaN
plays the role!)
•
High switching turn-off losses
(GaN plays the role!)
• At fsw>fr, freq is getting
high with high turn-off loss
 GaN has further
benefits for lowest turn-off
losses;
• At fsw<fr, there is a
primary circulating current
 GaN allows larger
magnetizing inductance
Lm with ZVS and reduces
the circulating loss
19
3kW Full Bridge LLC Converter (GS-EVB-LLC-3KW-GS)
Syn- Full Bridge LLC DC/DC
+
Secondary PWM Driver
Input Voltage range:
Output Voltage:
Full Load Current:
Topology:
Target frequency:
Peak efficiency:
PCBA board size:
Power Density:
Primary PWM Driver
•
•
•
•
•
•
•
•
54V
3000W max
380V-420V
Main Specifications:
+
380Vdc~420Vdc
54V
Digital Control
55A
SR Full Bridge LLC Resonant Converter
250KHz (resonant frequency)
>98%
80mmx140mmx30mm (air-forced cooling)
146W/inch3 (air-forced cooling)
-
GaN daughter board
• GS-065-030-2-L for Full bridge LLC (total 4pcs with 1pcs per switch)
• GS-065-004-1-L for the auxiliary power (1pcs for QR Flyback)
End Applications:
• Datacenter/Server Power Converter
• Telecom SMPS
• Industrial SMPS
Efficiency
GaN Systems Parts:
99%
98%
97%
96%
95%
94%
93%
92%
91%
90%
GS-065-030-2-L
8x8 PQFN
GS-065-004-1-L
5x6 PQFN
98.2%
400Vin
0
20
3kW full bridge GaN LLC achieves >98% efficiency
Io(A)
40
60
20
3kW Full Bridge LLC Block (GS-EVB-LLC-3KW-GS)
Vin +
V
DC/DC
PWMH1
380V~420V
DC/DC
10VP
5.8V/-3V
Si8271AB
5VPAUX
V1H
PWMH2
PWML1
5.8V/-3V
Si8271AB
V1L
PWRGND
IPRI
SR1
5VS
OUTD
HS/LS
SR on-time
Shoot-through OUTC
clamp
protect
10VS
SR2
PWML2
SDGND
PGND
SDGND
VBULK
PGND
SDGND
IPRI
PGND
SDGND
CS+
10VS
SDGND
LDO
IXDN609
Fsw
3.3V VDA
INA213DCK
SAGND
Frequency
Freq Clamp
Protection/CTR
PGOOD
OCP_pri (HW)
OCP_sec (ADC)
-
PI
+
Vref
MCU enable &
System Protections
STM32F334C8
NCP1380
Vo sample
Vo
3.3V
VDD
LDO
SDGND
LDO
PGND
SAGND
5VS
GaN
GS-065-004-1-L
10VP
SDGND
MCU State Machine
0.5
+
PGND
12VSFAN
SDGND
5VS
Duty Clamp
SDGND
10VS for system
-
SDGND
IXDN609
SDGND
D
+
10VP for system
-
A
PGND
OUTAO
OUTB
HS/LS
Dead time
ISO7740 OUTAO Shoot-through OUTA
Cal.
protect
PWMH2
10VS
SR1
GS-065-030-2-L
CS+
3KW Full Bridge LLC Converter MCU Board
Primary Secondary
SR2
IPB044N15N5
x2pcs
IPB044N15N5
x2pcs
0Ω
PWRGND
54V
15:2:2
GaN Board
#2
GS-065-030-2-L
Secondary
SDGND
V2L
PGND
GaN Board
#1
+ Vo
A
5.8V/-3V
Si8271AB
PWML2
PQ4030
Lm=75uH
Cr=27nF
DC/DC
10VP
5VPAUX
PGND
-
PQ3220
Lr=15uH
PGND
DC/DC
10VP
Primary
VBULK
5.8V/-3V
V2H
Si8271AB
PGND
5VPAUX
PWML1
Vo
V
10VP
5VPAUX
Secondary
Primary
5VPAUX
PWMH1
3KW Full Bridge LLC Converter Auxiliary Power Board
3KW Full Bridge LLC Converter Main Board
VBULK
3.3V
VDA
0Ω
5VPAUX
PWRGND
0Ω
PWRGND
PGND
3kW LLC System Block:
• Full -bridge LLC Motherboard
• GaN power board #1
• GaN power board #2
• Auxiliary (Aux) power board
• MCU board
SAGND
21
3kW LLC Resonant Tank and Loss
2
2
light load
M ( f , Qe1) 1.64
Resonant Freq.
=250KHz
M ( f , Qe2)
M ( f , Qe3) 1.28
Full load
M ( f , Qe4)
Mmax
3kW LLC Converter Loss (W)
380V input
420V input
0.92
Mmin
0.56
0.2
0
0
•
5
1×10
5
5
2×10
Transformer Tr
3×10
f


Core: PQ4030 Lm=75µH
Turns: 15:2:2Ts


Core: PQ3220 Lr=15µH
Winding: 0.1mm*200 15Ts

Cr=27nF
•
Resonant Inductor Lr
•
Resonant Capacitor Cr
4×10
5
5×10
13.6
23
Heavy load
0.2
5
5
4
15
11.2
2
5
500000
GaN_conduction
GaN_Turn-off
GaN_deadtime
SR MOS
Resonat Ind Lr
Transformer Tr
12V Fan
Aux power
The resonant frequency is 250kHz with max frequency up to ~400kHz
22
3kW LLC High Frequency Transformer Design #1
Calculate Ap as the formula below:
Isrms 
⋅ 2
Nps ⋅ Vs ⋅ 0.5⋅  Iprms +
Nps 

Ap :=
Core Selection
Core
3C96
3C97
TPW33
DMR96
ui
3000
3000
3300
3500
Bmax
530mT@25C
410mT@100C
550mT@25C
430mT@100C
520mT@25C
410mT@100C
540mT@25C
430mT@100C
Pv(200mT/1
00KHz)
630KW/m^3@25
C
300KW/m^3@10
0C
360KW/m^3@25C
320KW/m^3@100
C
380KW/m^3@25C
300KW/m^3@100
C
290KW/m^3@25
C
280KW/m^3@10
0C
Temp_
optimized
25-100C
50-150C
25-120C
25-120C
Frequency
• From the formula result, the design needed Ap is:
Range
3.3*10^4
mm^4;
• 3C96 core is selected. and DMR96 can
• PQ4030 is selected, which Ae*Aw is 3.9*10^4 mm^4. Vendor
<500KHz
<500KHz
<500KHz
<600KHz
•
•
•
•
•
•
•
•
fr⋅ ∆B ⋅ K⋅ J_mt
Nps is the turns ratio;
Vs is the output voltage plus forward drop of rectifier;
Iprms is the primary RMS Current
Isrms is the secondary RMS Current;
fr is the resonant frequency;
△B is the flux density;
K is the filling factor of transformer;
J_mt is current density;
• The max operation frequency is 400KHz
• Penetrate depth calculated as below:
∆ :=
7.5cm
400000
−4
= 1.186 × 10
m
beFerroxcube
used for further
optimization.
Ferroxcube efficiency
TDG
DMEGC
Winding Design
The winding diameter need to be less than 2*
△, which is less than 0.23mm
• Primary winding is 0.1mm*200 litz wire for 9A rms current
• Secondary winding is 0.2mm*7.5mm*4 parallel flat copper for 43.3A rms current
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3kW LLC High Frequency Transformer Design #2
PQ4030 3C96
Distributed
air-gap
Fringing field and winding loss near the
single big air gap
Distributed air-gap to minimize the fringing field
and winding loss at high frequency
Large leakage energy and loss
Interleaved structure(P-S1-S2-P) to minimize
the leakage inductance to keep the
consistency of resonant parameters
LLC transformer is optimized with high frequency
Reference : Zhang Jun, Analysis and design of high frequency gapped transformers and planar transformers in LLC resonant converters. May 2015
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GaN Based 3kW AC/DC PSU
25
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GaN based 3kW AC/DC PSU with 80+ Titanium
80+ Efficiency Level Certificates
VAC
Input Voltage (Vin)
Output Voltage (Vo)
Max. Output Power (Po)
Full Load Output Current (Io)
PFC frequency(fsw)
LLC Resonant frequency (fr)
90V~264V
54 V
3000 W for high line AC
1500W for low line AC
55 A
65KHz
250 KHz
LLC Max. Switching frequency (fmax)
400 KHz
Performance
Specification
140 mmx100mmX80 mm
(with air-forced cooling fan)
>96%
DC voltage brown-out, output short, output
OCP, primary OCP
80+ Titanium
AC/DC PCBA Board Size
Peak Efficiency
System Protections
Energy Star
AC/DC
3kW PSU
Isolated DC/DC
400 VDC
PFC
54V/55A
LLC
+
+
L
54V/3000W
90V~264Vac
Bridgeless Totem Pole PFC
Full Bridge LLC DC/DC
GS-EVB-BTP-3KW-GS
(3kW Totem Pole PFC)
3kW BTP PFC+LLC is verified with high performance
GS-EVB-LLC-3KW-GS
(3kW LLC)
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3kW AC/DC PSU Efficiency
Efficiency
3kW GaN based PSU bench setup
98%
97%
96%
95%
94%
93%
92%
91%
90%
89%
88%
87%
3KW PFC+LLC Efficiency @230Vac Input
94%
96%
90%
10%
20%
50%
91%
100%
Output Power Percentage
230V 80+ Titanium
3kW full GaN PSU
Note: Include aux power for PFC+LLC, exclude air-forced cooling
3kW AC/DC PSU Efficiency:
• Meet 80+ Titanium with 10%, 20% 50% and 100% load
• Full load efficiency above 95%
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3kW AC/DC PSU Thermal Test @230Vac
GS-EVB-BTP-3KWGS
(3kW Totem Pole
PFC)
Cooling Fan
GS-EVB-BTP-3KW-GS
(3kW Totem Pole PFC)
GS-EVB-LLC-3KW-GS
(3kW LLC)
80mm
GS-EVB-LLC-3KW-GS
(3kW LLC)
140mm
LLC’s GaN
3kW AC/DC PSU Efficiency:
• Highest Tmax at LLC transformer, ~100°C
• BTP PFC’s GaN: 57°C & LLC’s GaN: 78°C
BTP PFC’s GaN
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3kW AC/DC PSU Waveform (PFC stage）
• Steady state
• Start up
3kW AC/DC PSU PFC Stage:
• Steady state waveform with high power factor above 0.99
• Soft-start control without big inrush current during start up
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3kW AC/DC PSU Waveform (LLC stage）
~250kHz Steady State
• Steady state
~400kHz Startup
CH1: Output voltage (20v/div)
CH2: Ipri, primary resonant current (20A/div)
CH3: GaN Vgs voltage (10v/div)
CH4: Sec Vgs voltage (10v/div)
• Start up
3kW AC/DC PSU LLC Stage:
• Soft-start up at 400kHz frequency without big inrush current
• Steady state at 250kHz resonant frequency at full load
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Datacenter PSU Pareto Analysis Results
Only GaN-based PSU achieves:
• 80+ Titanium+ efficiency
+
• >80W/in3 power density
Target power density
>80W/in3
Source: www.eenewspower.com/news/pareto-analysis-gan-cost-savings-data-centre/page/0/1#
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Designing a 3kW AC/DC PSU
• 80+ Titanium
 High efficiency at 50% and 100% load is easy to achieve with GaN
 10% and 20% light load efficiency is a challenge, GaN meets targets
 GaN Systems’ know-how:
o LLC transformer/inductor core material design
o Aux power design
o Enabling cycle by cycle control with lower Rdson GaN, thermal design etc…
• Power Density
 Moving to above 80W/inch3 while targeting Titanium+ requires GaN
 GaN Systems’ know-how:
o Delete bulk capacitors (the EVB duplicates the bulk capacitors for PFC and LLC)
o 3D mechanical designs (cooling fans, heatsinks, passive components)
o Compact PFC design (advanced design available soon)
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GaN solves 3 design challenges
Increase Efficiency
Reduce Emissions
98%
96%
94%
Mainstream
Reduce Size
Silicon
MOSFET
Best
Good
Today’s
requirements
• Reduce creation of heat
by being more efficient.
• Significant reduction in
electricity costs.
• Every efficiency percentage
point increase reduces need
for power which lessens the
environmental impact and
reduces carbon emissions.
• Industry demanding sharp
increase in size reduction.
• High-power, high efficiency in
the smallest form factor.
• More real estate to add more
CPU and memory components.
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GaN-based Power Supplies
• Increase profits
• Reduce CO2 emissions
• Reduce OPEX
The numbers for a 10-Rack set
$
PROFIT
$3M profit increase/year/10-Rack
100 metric tons reduction/year/10-Rack
$
OPEX
10-Rack set
$13K OPEX reduction/year/10-Rack
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Summary
GaN based 3kW AC/DC PSU:
• 80+ Titanium
• Power density > 80W/in3
With GaN, Data Centers Have
More Servers & Storage Per Rack
Contact us to help you with your
design at www.gansystems.com
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