FA6A01N [FUJI]
2nd Generation LLC Current Resonant Control IC, âFA6A00N Seriesâ;
| 型号： | FA6A01N |
| 厂家： | 
FUJI ELECTRIC |
| 描述： | 2nd Generation LLC Current Resonant Control IC, âFA6A00N Seriesâ |
| 文件： | 总7页 (文件大小：273K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
2nd Generation LLC Current Resonant Control IC,
“FA6A00N Series”
CHEN Jian* YAMADAYA Masayuki* SHIROYAMA Hironobu㾙
A B S T R A C T
LLC current resonant power supply, which is characterized by soft switching, resonance control with a duty ratio
of 50% and leakage transformer structure, is suitable for efficiency improvement, noise reduction and profile lower-
ing in switching power supply. Fuji Electric has developed the 2nd generation “FA6A00N Series,” which inherits the
characteristics of the 1st generation LLC current resonant control IC, “FA5760N,” and is enhanced with lower standby
power and improved protective functions. It integrates the world’s first high-precision secondary side over-load pro-
tection function while further reducing the standby power by approximately 20%. For the over-current protection
function, the delay time can be externally adjusted.
1. Introduction
standby converter and allows a power management
system configuration that offers high efficiency, low
standby power and compactness. This has expanded
the scope of its application such that it is adopted to a
power supply of about 50 W without a PFC converter.
Fuji Electric has recently developed the “FA6A00N
Series,” the 2nd-generation LLC current resonant con-
trol IC. With the characteristics of the 1st-generation
LLC current resonant control IC “FA5760N” inherited,
it is enhanced with a lower standby power, improved
protective functions, higher quality and lower system
cost and offers a higher degree of design freedom.
Switching power supply products, which are used
in various types of electronic equipment, are rapidly
being improved in terms of efficiency, noise reduction
and low profile to meet the demands for energy ef-
ficiency and space saving. An LLC current resonant
power supply is characterized by its use of high-effi-
ciency, low-noise soft switching technology and low-
profile leakage transformer structure. These charac-
teristics facilitate efficiency improvement, noise reduc-
tion and profile lowering and make it suitable for use
as a power supply of 100 to 500 W, which is a medium
capacity range for a switching power supply. The LLC
current resonant power supply, however, is prone to a
switching shoot-through phenomenon*1 during a start-
up, heavy load conditions or low input voltage condi-
tions. The power supply has problems including a
breakdown of a power metal-oxide-semiconductor field-
effect transistor (MOSFET) due to this phenomenon
and efficiency degradation with a light load due to an
excitation current, and these factors limited its scope
of application.
2. Overview of Product
Figure 1 shows the external appearance of the
FA6A00N Series and Fig 2 the block diagram. Table
1 lists the major ratings, Table 2 the major functions
and Table 3 shows the product lineup. The following
outlines the LLC current resonant control IC of the
FA6A00N Series.
In order to solve these problems, Fuji Electric
commercialized “FA5760N,” an LLC current reso-
nant control IC that uses its unique new control sys-
tem. FA5760N is an LLC resonant converter that
eliminates the need for a PFC converter and dedicated
1: Switching shoot-through phenomenon: a phenomenon
in which, when a current flows through the body diode
of one power MOSFET in a bridge switching circuit, the
opposing power MOSFET turns on to instantaneously
generate a large current.
*
Electronic Devices Business Group, Fuji Electric Co., Ltd.
Sales Group, Fuji Electric Co., Ltd.
*
㾙
Fig.1 “FA6A00N Series”
245
VCC
VH
STB
MODE
Intemal
Supply
Regu-
lator
X-Cap
discharge
Standby control
circuit
State control
circuit
Start-up
circuit
VH
VCC_UVLO
VHOVP Msstb Mstb
BOP
Smode
voltage
detection
circuit
BO
BO
/PGS
BOPINP
DTadj
UVLO
+
-
-
+
VB
UVLO
High side
control circuit
HO
VS
LO
on_trg
off_trg
FB
CS
High side
driver
HO
control
Oscillator
Pulse by
pulse
protection
Continuous
protection
VCC
LO
control
FB
FB
Low side driver
Control
circuit
OLP
OCP
CS
Continuous
Protection
VHOVP
UVLO
Protection
circuit
BOP
BOPINP
Mstb
Soft start
control
circuit
Msstb
Pulse-by-
pulse
Protection
FTO
Dadj
VW_OLP
Pulse-by-
pulse
Self-
VW OLP
protection
circuit
CS
Control turn-off
Mstb
adjusting
dead time
detection
circuit
CS
VCC
Standby
control
circuit
Smode
Smode
GND
Mstb
Msstb
IS
VW
Fig.2 “FA6A00N Series” block diagram
Table 1 Major ratings
Table 3 Product lineup
Item
Rated value
Product
Overload
Over-current
protection
Terminal 3
name
protection
Auto-restart
Auto-restart
Auto-restart
Latch stop
High side power supply voltage to ground
–0.3 to +630 V
–0.3 to +30 V
–0.3 to +30 V
–0.3 to +600 V
FA6A00N
FA6A01N
FA6A10N
FA6A11N
PGS terminal
PGS terminal
BO terminal
BO terminal
Latch stop
Auto-restart
Auto-restart
Latch stop
High side power supply voltage (VBS
)
Low side power supply voltage (VCC
)
VH terminal input voltage
Maximum allowable offset power supply
±50 kV/μs (max.)
voltage dv/dt
Total loss
0.83 W
(a) Control circuit with 3.3 V, 5 V and 30 V break-
down voltage for controlling the LLC current
resonant circuit
Operating junction temperature
–40 to +150°C
(b) Driver circuit with 630 V breakdown voltage
capable of directly driving the high side and low
side switching devices in the half bridge circuit
(c) Built-in 600 V breakdown voltage start-up de-
vice realizing IC start-up with low power con-
sumption
Table 2 Major functions and terminals
Function
Terminal (No.)
Start-up circuit
VH (1), VCC (10)
Low voltage malfunction prevention circuit VCC (10), VB (16)
State setting function
MODE (7)
VH (1)
X-Cap discharge function
Fixed brown-in/brown-out
Variable brown-in/brown-out
Overvoltage protection
(d) JEDEC-compliant 16-pin small outline package
The high side and low side outputs alternately op-
erate with a high-precision duty cycle of 50% and the
operating frequency range is 38 to 350 kHz.
VH (1)
BO (3)
VH (1), VCC (10)
Over-current protection with variable
delay time
IS (8), MODE (7)
3. Features
Overload protection
VW (9), FB (4)
Integrated
MODE (7)
VW (9), IS (8)
VW (9)
Overheat protection
3.1 Low power dissipation burst control
External latch signal input
Forced turn-off function
FA5760N, the 1st-generation product, used the
VCC and CS terminals for hysteresis burst control and
achieved a world-class low standby power without the
standby converter. The FA6A00N Series, which is the
2nd generation, is additionally provided with burst
control optimization to further reduce the standby
power by approximately 20% from FA5760N.
Automatic dead time adjustment function
High-precision overload protection function
Soft start function
VW (9)
CS (5)
VCC (10), CS (5),
VH (1)
Low standby power operation mode
Power Good signal
PGS (3)
The LLC current resonant control has a high side
FUJI ELECTRIC REVIEW vol.59 no.4 2013
246
3
2
Range of frequency variation
during normal operation
+
S1
S2
Range of frequency
variation during
burst operation
P1
HO
+
Vi
VS
LO
Aux
1
0
P2
0
50
100
150
200
Fig.5 Schematic circuit diagram of current resonance
Frequency (kHz)
Fig.3 Current resonant gain diagram
protecting the power management system, is a func-
tion that stops switching when a certain delay time
has elapsed after a load increases to approximately
1.5 times the rated load. Degradation of the preci-
sion of this function causes insufficient output power
or failure to limit the output power, thus the overload
protection cannot perform adequately. In addition, the
overload protection level must be maintained within
a certain range (about ±20%) even if an input voltage
varies in a wide range.
Figure 6 shows the circuit configuration of the high-
precision overload protection function of the FA6A00N
Series. The auxiliary winding voltage is detected by
the resistor-divided voltage, VW voltage. The recom-
mended precision of this voltage-dividing resistor is
±1%. The VW voltage exceeding the threshold voltage
Volpvw is recognized as an overload state, and when
the overload state continues for 76.8 ms, switching is
stopped. In order to improve the detection precision,
variation of Volpvw has been specified to be within ±3%,
which is highly precise. The commercialized versions
are the auto-restart version, which restarts when the
switching stop time has reached 550 ms, and the latch
stop version that does not restart.
High
Invalid region
Region with high conversion efficiency
Region with low conversion efficiency
(1)
(2)
(3)
Low
FA5760N
FA6A00N Series
Fig.4 Frequency during burst operation
and low side duty cycle of 50% and controls the gain
by the switching frequency. Figure 3 shows the current
resonant gain diagram. The frequency variation range
is narrow in principle during normal operation and
widened during burst operation.
Figure 4 shows the frequency during burst opera-
tion. The high frequency region (1) is an invalid region
in which the gain is low and switching cannot trans-
fer energy. In the low frequency region (3), the gain
is high and excitation current is large, which makes
energy transfer inefficient; hence there is a low conver-
sion efficiency. With the FA6A00N Series, the invalid
region and the region with low conversion efficiency
have been reduced to widen the region with high con-
version efficiency (2), resulting in successful reduction
of standby power. Audible noise has also been sup-
pressed.
Figure 7 shows a waveform during overload pro-
tection operation. In overload protection operation,
switching is suspended and the output voltage drops
along with an energy transfer stop.
Figure 8 shows how the overload protection oper-
ating power depends on the input voltage. FA5760N
provides overload protection with general resonant
current detection. With this method, the overload
Aux
3.2 High-precision overload protection function
R1
VW
The 1st-generation product FA5760N used the pri-
mary side auxiliary winding P2 (see Fig. 5) to supply
power to the VCC terminal and realized hard switch-
ing protection and shoot-through current prevention.
The FA6A00N Series, which is the 2nd generation,
uses this auxiliary winding to integrate the high-pre-
cision overload protection function for the first time in
the world while inheriting the functions of FA5760N.
The overload protection, which is intended for
P2
+
Delay circuit
Tolpdly = 76.8 ms
S
Q
Stop
switching
R2
-
Volpvw
Delay circuit
Tolpoff = 550 ms
R
Fig.6 Circuit configuration of high-precision overload protection
function
2nd Generation LLC Current Resonant Control IC, “FA6A00N Series”
247
Resonant current
Output voltage Vo
IS voltage
Peak value of VW voltage: 2.8 V
MODE voltage
VS voltage
VW voltage
Reference value of VW voltage: 0 V
Fig.9 Waveform during over-current protection operation
Fig.7 Operation waveform during overload protection
degree of flexibility in power supply design.
With the FA6A00N Series, adjustment of Tocp is
shared by the MODE terminal for state setting, which
has led to the realization of the over-current protection
function with a variable delay time without increasing
the number of terminals. Figure 9 shows a measured
waveform. When a resonant current rapidly increases,
an over-current state is detected on the IS terminal.
The MODE terminal voltage is clamped to 0.5 V after
state setting and, when an overload state is detected,
oscillates between 0.6 and 0.8 V. When the number of
oscillations reaches 36, switching stops and provides
over-current protection. The duration of one oscilla-
tion can be adjusted by the capacitor connected to the
MODE terminal.
400
300
FA5760N
200
FA6A00N Series
100
0
50
100
150
200
250
300
Input voltage (V)
Fig.8 Input voltage and overload protection operating power
4. Effect on Application to Power Circuit
protection level is highly dependent on the input volt-
age when the input voltage range is wide, and this has
necessitated the addition of a dedicated overload pro-
tection circuit. With the FA6A00N Series, variation of
the overload protection level is small even if the input
voltage varies, allowing for a high-accuracy overload
protection function without a dedicated overload pro-
tection circuit. As a result, the number of power sup-
ply system components can be reduced, allowing for a
cost reduction of a power supply system.
4.1 Standby power reduction effect
Figure 10 shows a sample application circuit and
Tables 4 and 5 the specification of the sample appli-
cation circuit and major semiconductor components
in the circuit. Figure 11 shows the measured standby
power with a 35 mW load. The FA6A00N Series can
reduce the standby power by approximately 20% from
FA5760N, which allows elimination of the standby
converter even if requirements for standby power are
severe.
3.3 Over-current protection function with variable delay
time
4.2 Number of circuit components reduction effect
When a load short circuit occurs and an over-
Figure 12 shows the configuration of a general LLC
current resonant power supply. A general LLC cur-
rent resonant power supply is composed of a filter for
EMI (electromagnetic interference) noise elimination,
PFC converter for power factor correction, standby con-
verter and LLC converter. Use of the FA6A00N Series
allows significant reduction in the number of compo-
nents, making it possible to build a low-cost LLC cur-
rent resonant power supply (see Table 6).
current state has continued for the specified time Tocp
,
switching stops. This is called the over-current protec-
tion function. The power device has a possibility of
being damaged if the Tocp setting is too long. If the
Tocp setting is too short, it causes an over-current state
at start-up, and this may be detected as a load short
circuit state and might hinder the start-up. The opti-
mum Tocp depends on a power supply and capability to
adjust Tocp with an external component offers a higher
FUJI ELECTRIC REVIEW vol.59 no.4 2013
248
YG865C10R
(100 V/20 A)
Output 1
24 V/3 A
+
FA6A00N Series
S1
S2
16
Input 85 to
264 V AC
GND
1
VB
HO 15
+
VH
P1
FMV23N50E
（500 V/23 A/
0ꢀ245 ）
6
5
3
STB
CS
YG862C06R
(60 V/10 A)
VS
14
/0.245）
BO/PGS
Output 2
12 V/2 A
10 VCC
+
FMV23N50E
(500 V/23 A/
0.245 )
MODE
7
4
S3
S4
LO 11
FB
GND
/0.245)
9
VW
PC1
GND IS
12
8
+
P2
PC2
Output 3
5V/1A
GND
On-Off signal
input
GND
PC2
+
PC1
8
7
6
5
FA7764
1
+
2
3
4
Fig.10 Sample application circuit
Table 4 Specifications of sample application circuit
Item Characteristic, etc.
Input voltage 85 to 264 V AC
200
150
FA5760N
Output voltage/current
Output power
24 V/3 A, 12 V/2 A, 5 V/1 A
100 W (max.)
100
50
0
Table 5 Major semiconductor components in sample applica-
tion circuit
FA6A00N Series
Component
Control IC
Model
FA6A00N Series
Bridge MOSFET
Diode (24 V)
FMV23N50E (500 V/23 A/0.245 Ω)
YG865C10R (100 V/20 A)
YG862C06R (60 V/10 A)
FA7764AN
50
100
150
200
250
300
Input voltage (V)
Diode (12 V)
5 V AC/DC converter
Fig.11 Standby power with 35 mW load
Filter
Vac
PFC converter
LLC converter
+
Output
1
S1
P1
Vi
PFC
control
IC
S2
+
LLC
control
IC
VS
DC-DC
circuit
OLP circuit
+
VCC
+
Output
2
PWM
(pulse width
modulation)
control IC
Standby converter
Fig.12 Configuration of general LLC current resonant power supply
2nd Generation LLC Current Resonant Control IC, “FA6A00N Series”
249
Table 6 Comparison on number (approximate number) of components
LLC converter
PFC
converter
Standby
converter
Total number of
components
Filter
High-precision
Main
DC-DC
OLP
FA5760N
10
10
10
30
30
40
60
60
60
Not required
10
150
120
90
75 W or more
Not required
20
20
Not required
Not required
FA6A00N
Series
less than 75 W
Not required Not required
tion of current resonant control with features including
the high-precision overload protection function.
We intend to continue working on establishing new
technologies that realize even higher efficiency and
further noise reduction, and developing power supply
control ICs that contribute to the miniaturization and
profile lowering of power supply.
5. Postscript
This paper has described the 2nd-generation LLC
current resonant control IC “FA6A00N Series.” This
IC, which inherits the characteristics of the 1st-gener-
ation product “FA5760N,” has achieved further evolu-
FUJI ELECTRIC REVIEW vol.59 no.4 2013
250
＊All brand names and product names in this journal might be trademarks
or registered trademarks of their respective companies.
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