dm00044789

AN4027
Application note
12 V - 150 W resonant converter with synchronous rectification
using the L6563H, L6699 and SRK2000A
Claudio Spini
Introduction
This application note describes the EVL6699-150W-SR demonstration board features,
a 12 V - 150 W converter tailored to a typical specification of an all-in-one (AIO) computer
power supply or a high power adapter.
The architecture is based on a two-stage approach: a front-end PFC pre-regulator based on
the L6563H TM PFC controller and a downstream LLC resonant half bridge converter using
the new L6699 resonant controller. The L6699 device integrates some very innovative
functions such as self-adjusting adaptive deadtime, anti-capacitive mode protection and
proprietary “safe-start” procedure preventing hard switching at startup.
Thanks to the chipset used, the main features of this power supply are very high efficiency,
compliant with ENERGY STAR® eligibility criteria for adapters (ENERGY STAR® rev. 2.0 for
external power supplies) and with the latest ENERGY STAR® qualification criteria for
computers (ENERGY STAR® ver. 6.0 for computers). The power supply also has very good
efficiency at light load too and no load input power consumption is very low as well, making
the board compliant with the requirements of the latest European Code of Conduct (CoC)
Tier 2 and EuP Lot 6 Tier 2.
Figure 1. EVL6699-150W-SR: 150 W SMPS demonstration board
April 2014
DocID022604 Rev 3
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www.st.com
Contents
AN4027
Contents
1
2
Main characteristics and circuit description . . . . . . . . . . . . . . . . . . . . . 6
1.1
Standby power saving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.2
Startup sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.3
L6563H brownout protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.4
L6563H fast voltage feed-forward . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.5
L6699 overload and short-circuit protection . . . . . . . . . . . . . . . . . . . . . . . 10
1.6
L6699 anti-capacitive protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.7
Output voltage feedback loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
1.8
Open loop protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Efficiency measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.1
ENERGY STAR® for external power supplies ver. 2.0 compliance
verification 14
2.2
ENERGY STAR® for computers ver. 6.0 compliance verification . . . . . . 15
2.3
Light load operation efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Measurement procedure: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3
Harmonic content measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4
Functional check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.1
Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.2
Burst mode operation at light load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
4.3
Overcurrent and short-circuit protection . . . . . . . . . . . . . . . . . . . . . . . . . . 22
4.4
Anti-capacitive mode protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5
Thermal map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
6
Conducted emission pre-compliance test . . . . . . . . . . . . . . . . . . . . . . 28
7
Bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
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Contents
PFC coil specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
8.1
General description and characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 35
8.2
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
8.3
Electrical diagram and winding characteristics . . . . . . . . . . . . . . . . . . . . . 35
8.4
Mechanical aspect and pin numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
8.5
Manufacturer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Transformer specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
9.1
General description and characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 37
9.2
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
9.3
Electrical diagram and winding characteristics . . . . . . . . . . . . . . . . . . . . . 37
9.4
Mechanical aspect and pin numbering . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
9.5
Manufacturer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
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List of tables
AN4027
List of tables
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Table 7.
Table 8.
Table 9.
Table 10.
Table 11.
4/41
Main characteristics and circuit description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Efficiency measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
European CoC Tier 2 and ENERGY STAR® ver. 2.0 for external power supplies
compliance verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
ENERGY STAR® for computers ver. 6.0 compliance verification. . . . . . . . . . . . . . . . . . . . 15
Light load efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Thermal maps reference points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
EVL6699-150W-SR demonstration board: motherboard bill of material. . . . . . . . . . . . . . . 29
EVL6699-150W-SR demonstration board: daughterboard bill of material . . . . . . . . . . . . . 33
PFC coil winding data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Transformer winding data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
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List of figures
List of figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
Figure 14.
Figure 15.
Figure 16.
Figure 17.
Figure 18.
Figure 19.
Figure 20.
Figure 21.
Figure 22.
Figure 23.
Figure 24.
Figure 25.
Figure 26.
Figure 27.
Figure 28.
Figure 29.
Figure 30.
Figure 31.
Figure 32.
Figure 33.
Figure 34.
Figure 35.
Figure 36.
EVL6699-150W-SR: 150 W SMPS demonstration board. . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Burst-mode circuit block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Electrical diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Graph of efficiency measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Light load efficiency diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Compliance to EN61000-3-2 at 230 Vac - 50 Hz, full load . . . . . . . . . . . . . . . . . . . . . . . . . 17
Compliance to JEITA-MITI at 100 Vac - 50 Hz, full load . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Mains voltage and current waveforms at 230 V - 50 Hz - full load . . . . . . . . . . . . . . . . . . . 17
Mains voltage and current waveforms at 100 V - 50 Hz - full load . . . . . . . . . . . . . . . . . . . 17
Resonant stage waveforms at 115 Vac - 60 Hz - full load. . . . . . . . . . . . . . . . . . . . . . . . . . 18
SRK2000A key signals at 115 Vac - 60 Hz - full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
HB transition at full load - rising edge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
HB transition at full load - falling edge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
HB transition at 0.25 A - rising edge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
HB transition at 0.25 A - falling edge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
L6699 pin signals-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
L6699 pin signals-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Startup at 90 Vac - full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Startup at 265 Vac - no load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Startup at 115 Vac - full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Startup at full load - detail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Pout = 250 mW operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Pout = 250 mW operation - detail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Transition full load to no load at 115 Vac - 60 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Transition no load to full load at 115 Vac - 60 Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Short-circuit at full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Short-circuit at full load – detail. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Short-circuit - hiccup mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Thermal map at 115 Vac - 60 Hz - full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Thermal map at 230 Vac - 50 Hz - full load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
CE average measurement at 115 Vac - 60 Hz and full load. . . . . . . . . . . . . . . . . . . . . . . . 28
CE average measurement at 230 Vac - 50 Hz and full load. . . . . . . . . . . . . . . . . . . . . . . . 28
PFC coil electrical diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
PFC coil mechanical aspect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Transformer electrical diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Transformer overall drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
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Main characteristics and circuit description
1
AN4027
Main characteristics and circuit description
The SMPS main features are listed below:
Table 1. Main characteristics and circuit description
Parameter
Value
Input mains range
90 - 264 Vac - frequency 45 to 65 Hz
Output voltage
12 V at 12.5 A continuous operation
Mains harmonics
Meets EN61000-3-2 Class-D and JEITA-MITI Class-D
No load mains consumption
< 0.15 W according to European CoC Tier 2 for external
power supplies
Minimum four points average efficiency in
active mode
> 89% according to European CoC Tier 2 for external
power supplies
Minimum efficiency in active mode at 10 %
load of full rated output current
> 79% according to European CoC Tier 2 for external
power supplies
EMI
Within EN55022 Class-B limits
Safety
Meets EN60950
Dimensions
65 x 154 mm, 28 mm component maximum height
PCB
Double side, 70 µm, FR-4, mixed PTH/SMT
The circuit is made up of two stages: a front-end PFC using the L6563H, an LLC resonant
converter based on the L6699, and the SRK2000A, controlling the SR MOSFETs on the
secondary side. The SR driver and the rectifier MOSFETs are mounted on a daughterboard.
The L6563H is a current mode PFC controller operating in transition mode and implements
a high-voltage startup to power on the converter.
The L6699 integrates all the functions necessary to properly control the resonant converter
with a 50 % fixed duty cycle and working with variable frequency.
The output rectification is managed by the SRK2000A, an SR driver dedicated to LLC
resonant topology.
The PFC stage works as pre-regulator and powers the resonant stage with a constant
voltage of 400 V. The downstream converter operates only if the PFC is on and regulating.
In this way, the resonant stage can be optimized for a narrow input voltage range.
The L6699 LINE pin (pin 7) is dedicated to this function. It is used to prevent the resonant
converter from working with too low input voltage that can cause incorrect Capacitive mode
operation. If the bulk voltage (PFC output) is below 380 V, the resonant startup is not
allowed. The L6699 LINE pin internal comparator has a current hysteresis allowing the turnon and turn-off voltage to be independently set. The turn-off threshold has been set to 300 V
to let the resonant stage operate in the case of mains sag and consequent PFC output dip.
The transformer uses the integrated magnetic approach, incorporating the resonant series
inductance. Therefore, no external, additional coil is needed for the resonance. The
transformer configuration chosen for the secondary winding is center tap.
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Main characteristics and circuit description
On the secondary side, the SRK2000A core function is to switch on each synchronous
rectifier MOSFET whenever the corresponding transformer half-winding starts conducting
(i.e. when the MOSFET body diode starts conducting) and then to switch it off when the
flowing current approaches zero. For this purpose, the IC is provided with two pins (DVS1
and DVS2) sensing the MOSFETs drain voltage level.
The SRK2000A automatically detects light load operation and enters sleep mode, disabling
MOSFET driving and decreasing its own consumption. This function allows great power
saving at light load with respect to benchmark SR solutions.
In order to decrease the output capacitors size, aluminium solid capacitors with very low
ESR were preferred to standard electrolytic ones. Therefore, high frequency output voltage
ripple is limited and an output LC filter is not required. This choice allows the saving of
output inductor power dissipation which can be significant in the case of high output current
applications such as this.
1.1
Standby power saving
The board has a burst mode function implemented that allows power saving during light
load operation.
The L6699 STBY pin (pin 5) senses the optocoupler’s collector voltage (U3), which is
related to the feedback control. This signal is compared to an internal reference (1.24 V). If
the voltage on the pin is lower than the reference, the IC enters an idle state and its
quiescent current is reduced. As the voltage exceeds the reference by 30 mV, the controller
restarts the switching. The burst mode operation load threshold can be programmed by
properly choosing the resistor connecting the optocoupler to pin RFMIN (R34). Basically,
R34 sets the switching frequency at which the controller enters burst mode. Since the power
at which the converter enters burst mode operation heavily influences converter efficiency at
light load, it must be properly set. However, despite this threshold being well set, if its
tolerance is too wide, the light load efficiency of mass production converters has
a considerable spread.
The main factors affecting the burst mode threshold tolerance are the control circuitry
tolerances and, even more influential, the tolerances of the resonant inductance and
resonant capacitor. Slight changes of resonance frequency can affect the switching
frequency and, consequently, notably change the burst mode threshold. Typical production
spread of these parameters, which fits the requirements of many applications, are no longer
acceptable if very low power consumption in standby must be guaranteed.
As reducing production tolerance of the resonant components causes a rise in cost, a new
cost-effective solution is necessary.
The key point of the proposed solution is to directly sense the output load to set the burst
mode threshold. In this way the resonant elements parameters no longer affect this
threshold. The implemented circuit block diagram is shown in Figure 2.
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Main characteristics and circuit description
AN4027
Figure 2. Burst-mode circuit block diagram
The output current is sensed by a resistor (RCS); the voltage drop across this resistor is
amplified by the TSC101, a dedicated high-side current sense amplifier; its output is
compared to a set reference by the TSM1014; if the output load is high, the signal fed into
the CC- pin is above the reference voltage, CC_OUT stays down and the optocoupler
transistor pulls up the L6699 STBY pin to the RFMIN voltage (2 V), setting continuous
switching operation (no burst mode); if the load decreases, the voltage on CC- falls below
the set threshold, CC_OUT goes high opening the connection between RFMIN and STBY
and allowing burst mode operation by the L6699. RCS is dimensioned considering two
constraints. The first is the maximum power dissipation allowed, based on the efficiency
target. The second limitation is imposed by the need to feed a reasonable voltage signal into
the TSM1014A inverting input. In fact, signals which are too small would affect system
accuracy.
On this board, the maximum acceptable power dissipation has been set to
Ploss,MAX = 500 mW. RCS maximum value is calculated as follows:
Equation 1
RCS,MAX =
Plo ss,MAX
= 3.2mΩ
I2out,MA X
The burst mode threshold is set at 18 W corresponding to IBM = 1.5 A output current at 12 V.
Choosing VCC+min = 300 mV as minimum reference of the TSM1014A, which permits
a good signal to noise ratio, the RCS minimum value is calculated as follows:
Equation 2
V CC + min
R CS min = --------------------------- = 2m
100  C BM
The actual value of the mounted resistor is 2 m, corresponding to Ploss = 312 mW power
losses at full load. The actual resistor value at the burst mode threshold current provides an
output voltage by the TSC101 of 83 mV. The reference voltage of TSM1014 Vcc+ must be
set at this level. The resistor divider setting the TSM1014 threshold RH and RL should be in
the range of k to minimize dissipation. Selecting RL = 22 K, the right RH value is obtained
as follows:
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Main characteristics and circuit description
Equation 3
R L  1.25V – V BM 
R H = ---------------------------------------------- = 69.67k
V BM
The value of the mounted resistor is 68 k.
RH sets a small debouncing hysteresis and is in the range of mega ohms. Rlim is in the
range of tens of k and limits the current flowing through the optocoupler's diode. Both
L6699 and L6563H implement their own burst mode function but, in order to improve the
power supply overall efficiency, at light load the L6699 drives the L6563H via the
PFC_STOP pin and enables the PFC burst mode: as soon as the L6699 stops switching
due to load drops, its PFC_STOP pin pulls down the L6563H PFC_OK pin, disabling PFC
switching. Thanks to this simple circuit, the PFC is forced into idle state when the resonant
stage is not switching and rapidly wakes up when the downstream converter restarts
switching.
1.2
Startup sequence
The PFC acts as master and the resonant stage can operate only if the PFC output is
delivering the rated output voltage. Therefore, the PFC starts first and then the LLC
converter turns on. At the beginning, the L6563H is supplied by the integrated high-voltage
startup circuit; as soon as the PFC starts switching, a charge pump circuit connected to the
PFC inductor supplies both PFC and resonant controllers, therefore, the HV internal current
source is disabled. Once both stages have been activated, the controllers are supplied also
by the auxiliary winding of the resonant transformer, assuring correct supply voltage even
during standby operation. As the L6563H integrated HV startup circuit is turned off, it greatly
contributes to power consumption reduction when the power supply operates at light load.
1.3
L6563H brownout protection
Brownout protection prevents the circuit from working with abnormal mains levels. It is easily
achieved using the RUN pin (pin 12) of the L6563H: this pin is connected through a resistor
divider to the VFF pin (pin 5), which provides the information of the mains voltage peak
value. An internal comparator enables the IC operations if the mains level is correct, within
the nominal limits. At startup, if the input voltage is below 90 Vac (typ.), circuit operations are
inhibited.
1.4
L6563H fast voltage feed-forward
The voltage on the L6563H VFF pin (pin 5) is the peak value of the voltage on the MULT pin
(pin 3). The RC network (R15 + R26, C12) connected to VFF completes a peak-holding
circuit. This signal is necessary to derive information from the RMS input voltage to
compensate the loop gain that is mains voltage dependent.
Generally speaking, if the time constant is too small, the voltage generated is affected by a
considerable amount of ripple at twice the mains frequency, therefore causing distortion of
the current reference (resulting in higher THD and lower PF). If the time constant is too
large, there is a considerable delay in setting the right amount of feed-forward, resulting in
excessive overshoot or undershoot of the pre-regulator's output voltage in response to large
line voltage changes.
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Main characteristics and circuit description
AN4027
To overcome this issue, the L6563H device implements the fast voltage feed-forward
function. As soon as the voltage on the VFF pin decreases by a set threshold (40 mV
typically), a mains dip is assumed and an internal switch rapidly discharges the VFF
capacitor via a 10 k resistor. Thanks to this feature, it is possible to set an RC circuit with
a long time constant, assuring a low THD, keeping a fast response to mains dip.
1.5
L6699 overload and short-circuit protection
The current into the primary winding is sensed by the lossless circuit R41, C27, R78, R79,
and C25 and it is fed into the ISEN pin (pin 6). In the case of overload, the voltage on the pin
surpasses an internal threshold (0.8 V) that triggers a protection sequence. An internal
switch is turned on for 5 µs and discharges the soft-start capacitor C18. This quickly
increases the oscillator frequency and thereby limits energy transfer. Under output shortcircuit conditions, this operation results in a peak primary current that periodically oscillates
below the maximum value allowed by the sense resistor R78.
The converter runs under this condition for a time set by the capacitor (C45) on pin DELAY
(pin 2). During this condition, C45 is charged by an internal 150 µA current generator and is
slowly discharged by the external resistor (R24). If the voltage on the pin reaches 2 V, the
soft-start capacitor is completely discharged so that the switching frequency is pushed to its
maximum value. As the voltage on the pin exceeds 3.5 V, the IC stops switching and the
internal generator is turned off, so that the voltage on the pin decays because of the external
resistor. The IC is soft-restarted as the voltage drops below 0.3 V. In this way, under shortcircuit conditions, the converter works intermittently with very low input average power.
This procedure allows the converter to handle an overload condition for a time lasting less
than a set value, avoiding IC shutdown in the case of short overload or peak power
transients. On the other hand, in the case of dead short, a second comparator referenced to
1.5 V immediately disables switching and activates a restart procedure.
1.6
L6699 anti-capacitive protection
The LLC resonant half bridge converter must operate with the resonant tank current lagging
behind the square-wave voltage applied by the half bridge leg. This is a necessary condition
in order to obtain correct soft switching by the half bridge MOSFETs. If the phase
relationship reverses, i.e. the resonant tank current leads the applied voltage, like in circuits
having a capacitive reactance, soft switching is lost. This condition is called capacitive mode
and must be avoided because of significant drawbacks coming from hard switching (refer to
the L6699 datasheet).
Resonant converters work in capacitive mode when their switching frequency falls below a
critical value that depends on the loading conditions and the input-to-output voltage ratio.
They are especially prone to run in capacitive mode when the input voltage is lower than the
minimum specified and/or the output is overloaded or short-circuited. Designing a converter
so that it never works in capacitive mode, even under abnormal operating conditions, is
certainly possible but this may pose unacceptable design constraints in some cases.
To prevent the severe drawbacks of capacitive mode operation, while enabling a design that
needs to ensure Inductive mode operation only in the specified operating range, neglecting
abnormal operating conditions, the L6699 provides the capacitive mode detection function.
The IC monitors the phase relationship between the tank current circuit sensed on the ISEN
pin and the voltage applied to the tank circuit by the half bridge, checking that the former
10/41
DocID022604 Rev 3
AN4027
Main characteristics and circuit description
lags behind the latter (Inductive mode operation). If the phase shift approaches zero, which
is indicative of impending capacitive mode operation, the monitoring circuit activates the
overload procedure described above so that the resulting frequency rise keeps the
converter away from that dangerous condition. Also in this case, the DELAY pin is activated,
so that the OLP function, if used, is eventually tripped after a time TSH causing intermittent
operation and reducing thermal stress.
If the phase relationship reverses abruptly (which may happen in the case of dead short at
the converter's output), the L6699 is stopped immediately, the soft-start capacitor C18 is
totally discharged and a new soft-start cycle is initiated after 50 µs idle time. During this idle
period the PFC_STOP pin is pulled low to stop the PFC stage as well.
1.7
Output voltage feedback loop
The feedback loop is implemented by means of a typical circuit using the dedicated
operational amplifier of the TSM1014A modulating the current in the optocoupler diode. The
second operational amplifier embedded in the TSM1014A, usually dedicated to constant
current regulation, is here utilized for burst mode as previously described.
On the primary side, R34 and D17 connect the RFMIN pin (pin 4) to the optocoupler's photo
transistor closing the feedback loop. R31, which connects the same pin to ground, sets the
minimum switching frequency. The RC series R44 and C18 sets both soft-start maximum
frequency and duration.
1.8
Open loop protection
Both circuit stages, PFC and resonant, are equipped with their own overvoltage protection.
The PFC controller L6563H monitors its output voltage via the resistor divider connected to
a dedicated pin (PFC_OK, pin 7) protecting the circuit in case of loop failures or
disconnection. If a fault condition is detected, the internal circuitry latches the L6563H
operations and, by means of the PWM_LATCH pin (pin 8), it latches the L6699 as well via
the DIS pin (pin 8). The converter is kept latched by the L6563H internal HV startup circuit
that supplies the IC by charging the VCC capacitor periodically. To resume converter
operation, mains restart is necessary. The LLC open loop protection is realized by
monitoring the output voltage through sensing the VCC voltage. If VCC voltage overrides the
D12 breakdown voltage, Q9 pulls down the L6563H INV pin latching the converter. Even in
this case, to resume converter operation, mains restart is necessary.
DocID022604 Rev 3
11/41
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Main characteristics and circuit description
AN4027
Figure 3. Electrical diagram
AN4027
2
Efficiency measurements
Efficiency measurements
Table 2 shows the no load consumption and the overall efficiency measurements at the
nominal mains voltages. At 115 Vac the full load efficiency is 91.5%, and at 230 Vac it is
93.2%, which are both high values for a double stage power supply and confirm the benefit
of implementing the synchronous rectification. The results are also shown in Figure 5 as
a graph.
Also at no load, the board performance is superior for a 150 W power supply: no load
consumption at nominal mains voltage is lower than 160 mW.
Table 2. Efficiency measurements
Input voltage
115 V - 60 Hz
230 V - 50 Hz
Load condition
Vout [V]
Iout [A]
Pout [W]
Pin [W]
Efficiency (%)
No load
12.00
0.00
0.00
0.132
-
10%
11.99
1.257
15.07
18.04
83.54
20%
11.99
2.50
29.98
35.58
84.2
25%
11.99
3.13
37.53
43.36
86.6
50%
11.97
6.25
74.81
82.53
90.6
75%
11.96
9.38
112.18
122.54
91.5
100%
11.94
12.50
149.25
163.12
91.5
No load
12.00
0.00
0.00
0.145
-
10%
11.98
1.258
15.07
17.43
86.46
20%
11.99
2.50
29.98
35.35
84.8
25%
11.98
3.14
37.62
43.27
86.9
50%
11.97
6.25
74.81
81.56
91.7
75%
11.96
9.38
112.18
120.66
93.0
100%
11.94
12.50
149.25
160.22
93.2
Figure 4. Graph of efficiency measurements
DocID022604 Rev 3
13/41
41
Efficiency measurements
2.1
AN4027
ENERGY STAR® for external power supplies ver. 2.0
compliance verification
In Table 3 the comparison between the regulation requirements and the test results are
reported: note that the design overcomes the requirements with margin. The average
efficiency is measured at 25 %, 50 %, 75 %, 100 % load, the no load input power
consumption and the power factor at full load meet these regulation requirements for
adapters.
Table 3. European CoC Tier 2 and ENERGY STAR® ver. 2.0 for external power
supplies compliance verification
2.2
European CoC Tier 2 and ENERGY
Test results
STAR® ver. 2.0 requirements for external
115 Vac - 60 Hz 230 Vac - 50 Hz
power supplies
Limits
Average efficiency 25 %, 50 %, 75 %, 100 %
load
0.901
0.912
> 0.87
Efficiency at 10% load
0.835
0.865
> 0.79
No load input power [W]
0.132 W
0.145 W
< 0.15 W
Power factor
0.991
0.972
> 0.9
Status
Pass
ENERGY STAR® for computers ver. 6.0 compliance
verification
Because the EVL6699-150W-SR design is suitable to power even all-in-one computers,
having to meet the ENERGY STAR® regulation for computers, the test results have been
compared with the latest ver. 6.0 requirements of this document. In the comparison
between the regulation requirements and the test results are reported: note that, in this case
the efficiency limit is not the average efficiency measured at different loads but there are
three different values of minimum efficiency to be met, at 20 %, 50 %, and 100 % load. Even
in this case, at full load the minimum power factor must be 0.9 minimum. In all load and line
conditions the EVL6699-150W-SR has efficiency and power factor much better than the
minimum required by the ENERGY STAR® regulation.
Table 4. ENERGY STAR® for computers ver. 6.0 compliance verification
Test results
ENERGY STAR® requirements for
14/41
Limits
computers ver. 6.0:
115 Vac - 60 Hz
230 Vac - 50 Hz
Efficiency at 20 % load
0.842
0.848
> 0.82
Efficiency at 50 % load
0.906
0.917
> 0.85
Efficiency at 100 % load
0.915
0.932
> 0.82
Power factor
0.991
0.972
> 0.9
DocID022604 Rev 3
Status
Pass
AN4027
2.3
Efficiency measurements
Light load operation efficiency
Computer power supplies must now meet higher efficiency limits than in the past even at
light load because, according to latest regulations such as the EuP Ecodesign requirements
for household and office equipment Lot 6 Tier 2, the maximum power consumption during
computer standby and off mode has decreased.
Measurement results are reported in Table 4 and plotted in Figure 5. As seen, efficiency is
better than 50% even for very light loads such as 250 mW. This high efficiency at light load
allows the board to meet also the regulation of the low power status ENERGY STAR®
program for computers ver. 5.0.
Measurement procedure:
1.
Because the current flowing through the circuit under measurement is relatively small,
the current measurement circuit is connected to the demonstration board side and the
voltage measurement circuit is connected to the AC source side. In this way, the
current absorbed by the voltage circuit is not considered in the measured consumption
amount.
2.
During any efficiency measurement, remove any oscilloscope probe from the board.
3.
For any measurement load, apply a warm-up time of 20 minutes by each different load.
Loads have been applied increasing the output power from minimum to maximum.
4.
Because of the input current shape during light load condition, the input power
measurement may be critical or unreliable using a power meter in the usual way. To
overcome this issue, all light measurements have been done by measuring the active
energy consumption of the demonstration board under test and then calculating the
power as the energy divided by the integration time. The integration time has been set
to 36 seconds, as a compromise between a reliable measurement and a reasonable
time measurement time. The energy is measured in mWh, the result in mW is then
simply calculated by dividing the instrument reading (in mWh) by 100. The instrument
used was the Yokogawa, WT210 power meter.
Table 5. Light load efficiency
230 V - 50 Hz
Test
Vout [V] Iout [mA]
115 V - 60 Hz
Pout
[W]
Pin [W]
Eff. [%] Vout [V] Iout [mA]
Pout
[W]
Pin [W]
Eff. [%]
0.25 W
12.00
10.40
0.125
0.319
39.1
12.00
10.40
0.125
0.310
40.3
0.5 W
12.00
20.90
0.251
0.473
53.0
12.00
20.90
0.251
0.471
53.2
1.0 W
12.00
41.68
0.500
0.768
65.1
12.00
41.68
0.500
0.785
63.7
1.5 W
12.00
83.50
1.002
1.358
73.8
12.00
83.50
1.002
1.415
70.8
2.0 W
12.00
125.03
1.500
1.940
77.3
12.00
125.03
1.500
2.045
73.4
2.5 W
12.00
167.09
2.005
2.525
79.4
12.00
166.84
2.002
2.651
75.5
3.0W
12.00
209.09
2.509
3.112
80.6
12.00
208.56
2.503
3.267
76.6
3.5 W
12.00
250.37
3.004
3.687
81.5
12.00
250.09
3.001
3.867
77.6
4.0 W
12.00
291.65
3.500
4.260
82.2
12.00
292.02
3.504
4.479
78.2
DocID022604 Rev 3
15/41
41
Efficiency measurements
AN4027
Table 5. Light load efficiency (continued)
230 V - 50 Hz
Test
Vout [V] Iout [mA]
115 V - 60 Hz
Pout
[W]
Pin [W]
Eff. [%] Vout [V] Iout [mA]
Pout
[W]
Pin [W]
Eff. [%]
4.5 W
12.00
333.65
4.004
4.844
82.7
12.00
333.65
4.004
5.090
78.7
5.0 W
12.00
375.43
4.505
5.423
83.1
12.00
375.65
4.508
5.683
79.3
Figure 5. Light load efficiency diagram
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16/41
DocID022604 Rev 3
AN4027
Harmonic content measurement
3
Harmonic content measurement
The board has been tested according to the European Standard EN61000-3-2 Class-D and
Japanese standard JEITA-MITI Class-D, at both the nominal input voltage mains. As
reported in the following figures, the circuit is able to reduce the harmonics well below the
limits of both regulations.
On the bottom side of the diagrams the total harmonic distortion and power factor have
been measured too. The values in all conditions give a clear idea about the correct
functionality of the PFC.
Figure 6. Compliance to EN61000-3-2 at 230 Vac Figure 7. Compliance to JEITA-MITI at 100 Vac - 50 Hz, full load
50 Hz, full load
Measured value
EN61000-3-2 Class-D limits
Measured value
JEITA-MITI Class-D limits
10
1
0.1
Harmonic Current [A]
Harrmonic Current [A]
1
0.01
0.001
0.1
0.01
0.001
0.0001
0.0001
1
3
5
7
9
1
11 13 15 17 19 21 23 25 27 29 31 33 35 37 39
3
5
7
9
11 13 15 17 19 21 23 25 27 29 31 33 35 37 39
Harmonic Order [n]
Harmonic Order [n]
THD: 7.5 % - PF = 0.933
THD: 18.2 % - PF = 0.972
AM11399v1
AM11400v1
In Figure 7 and Figure 8 the input mains current is shown at both nominal mains input
voltages, European and Japanese. At European mains the waveforms show a slightly
higher THD value because, in order to increase the efficiency, the PFC switching frequency
is limited to a value around 125 kHz. However, all harmonics are within the limits specified
by both regulations.
Figure 8. Mains voltage and current waveforms Figure 9. Mains voltage and current waveforms
at 230 V - 50 Hz - full load
at 100 V - 50 Hz - full load
CH1:
CH2:
Mains voltage
Mains current
AM11401v1
CH1:
CH2:
DocID022604 Rev 3
Mains voltage
Mains current
AM11402v1
17/41
41
Functional check
4
AN4027
Functional check
In Figure 10 some waveforms relevant to the resonant stage during steady-state operation
are reported. The selected switching frequency is about 120 kHz, in order to have a good
trade-off between transformer losses and dimensions. The converter operates slightly
above the resonance frequency. Figure 11 shows key signals of the SRK2000A: each
rectifier MOSFET is switched on and off according to its drain-source voltage which, during
conduction time, is the voltage of the current flowing through the MOSFET.
Figure 10. Resonant stage waveforms at 115 Vac Figure 11. SRK2000A key signals at 115 Vac - 60
- 60 Hz - full load
Hz - full load
CH1: HB voltage
CH2: LVG pin voltage
CH3: HVG pin voltage CH4: ISEN pin voltage
AM11403v1
CH1: GD1 pin voltage CH2: DVS1 pin
CH3: GD2 pin voltage CH4: DVS2 pin
AM11404v1
A peculiarity of the L6699 is the self-adaptive deadtime, modulated by the internal logic
according to the half bridge node transition time. This feature allows the maximization of the
transformer magnetizing inductance, therefore obtaining good light load efficiency and also
keeping correct operation by the HB. Figure 12 and Figure 13 show the waveforms during
full load operation. It is possible to note the measurement of the edges and the relevant
deadtime.
Figure 12. HB transition at full load - rising edge
CH1: HB voltage CH2: LVG
CH3: HVG
CH4: ISEN pin voltage
18/41
AM11405v1
Figure 13. HB transition at full load - falling
edge
CH1: HB voltage CH2: LVG
CH3: HVG
CH4: ISEN pin voltage
DocID022604 Rev 3
AM11406v1
AN4027
Functional check
In Figure 14 and Figure 15 the same images are captured during light load operation: note
that because of the resonant tank parameters, the half bridge transitions have similar rise
and fall times because the switched current is almost the same value in both load
conditions. In this case, the L6699 does not appreciably change the deadtime. In all
conditions it can be noted that both MOSFETs are turned on while resonant current is
flowing through their body diodes and drain-source voltage is zero, therefore achieving the
MOSFETs ZVS operation at turn-on.
Figure 14. HB transition at 0.25 A - rising edge
CH1: HB voltage
CH3: HVG
CH2: LVG
CH4: ISEN pin voltage
AM11407v1
Figure 15. HB transition at 0.25 A - falling edge
CH1: HB voltage
CH3: HVG
Figure 16. L6699 pin signals-1
CH1: DIS
CH2: LINE
CH3: DELAY CH4: ISEN
CH2: LVG
CH4: ISEN pin voltage
AM11408v1
Figure 17. L6699 pin signals-2
AM11409v1
CH1: RFmin
CH3: CSS
CH2: STBY
CH4: CF
AM11410v1
In Figure 16 some signals at L6699 pins are measured. It can be seen that the signal on the
ISEN pin (#6) matches the instantaneous current flowing in the transformer primary side.
Contrary to the former resonant controllers such as the L6599A and others, requiring an
integration of current signal, the L6699 integrates the anti-capacitive mode protection,
therefore it needs to sense the instantaneous value of the current in order to check the
phase between the voltage and current. The LINE pin (#7) has been dimensioned to start up
the L6699 once the PFC output voltage has reached the rated value, in order to have
correct converter sequencing, with PFC starting first and LLC starting later in order to
DocID022604 Rev 3
19/41
41
Functional check
AN4027
optimize the design of the LLC converter and prevent capacitive mode operation that may
occur because of operation at too low input voltage.
The DELAY pin (#2) is zero, as it must be during normal operation, because it works during
the overcurrent protection operation. The DIS pin (#8) is used for open loop protection and
therefore, even in this case, its voltage is at ground level.
In Figure 17 the pin voltages relevant to the control part of the L6699 are reported: the
RFmin pin (#4) is a 2 V (typ.) reference voltage of the oscillator, the switching frequency is
proportional to the current flowing out from the pin. CSS pin (#1) voltage is the same value
as pin #4 because it is connected to the latter via a resistor (R44), determining the soft-start
frequency. A capacitor (C18) is also connected between the CSS pin and ground, to set the
soft-start time. At the beginning of L6699 operation the voltage on the CSS pin is at ground
level because C18 is discharged, then the CSS pin (#1) voltage increases according to the
time constant till the RFmin voltage level is reached. The STBY pin (#5) senses the
optocoupler voltage; once the voltage decreases to 1.25 V, both gate drivers stop switching
and the circuit works in burst mode. The CF pin (#3) is the controller oscillator; its ramp
speed is proportional to the current flowing out from the RFmin pin (#4). The CF signal must
be clean and undistorted to obtain correct symmetry by the half bridge current, and
therefore care must be taken in the layout of the PCB.
4.1
Startup
The waveforms relevant to the board startup at 90 Vac and full load have been captured in
Figure 18. Note that the output voltage reaches the nominal value approximately 800 ms
after plug-in. The L6563H, HV PFC controller, has an embedded high-voltage startup
charging the Vcc capacitor by a constant current, ensuring a constant wake-up time. This
can be seen by comparing Figure 18 with Figure 19, relevant to a startup at 265 Vac and no
load, the output voltage rises at the nominal level in the same time. In both conditions the
output voltage has no overshoot or dips.
Figure 18. Startup at 90 Vac - full load
CH1: C9 bulk voltage CH2: GD L6563H
CH3: +12 Vout
CH4: VCC L6563H
AM11411v1
Figure 19. Startup at 265 Vac - no load
CH1: C9 bulk voltage CH2: GD L6563H
CH3: +12 Vout
CH4: VCC L6563H
AM11412v1
In Figure 20 the salient waveforms in the resonant tank during start up of the LLC are
reported. In Figure 21 the detail of waveforms at the beginning of operation shows that the
resonant circuit is working correctly in zero voltage switching operation from the initial
cycles. In the L6699 a new startup procedure, called “safe-start”, has been implemented in
20/41
DocID022604 Rev 3
AN4027
Functional check
order to prevent loss of soft-switching during the initial switching cycles which typically is not
guaranteed by the usual soft-start procedure. At startup, the voltage across the resonant
capacitor is often quite different from Vin/2, as during normal steady-state operation, so it
takes some time for its DC component to reach the steady-state value Vin/2. During this
transient, the transformer is not driven symmetrically and there is a significant V · s
imbalance in two consecutive half-cycles. If this imbalance is large, there is a significant
difference in the up and down slopes of the tank current and, in a typical controller working
with fixed 50% duty cycle, as the duration of the two half-cycles is the same, the current may
not reverse in a switching half-cycle. Therefore, one MOSFET can be turned on while the
body diode of the other is conducting and this may happen for a few cycles. To prevent this,
the L6699 is provided with a proprietary circuit that modifies the normal operation of the
oscillator during the initial switching cycles, so that the initial V · s unbalance is almost
eliminated. Its operation is such that current reversal in every switching half-cycle and, then,
soft-switching, is ensured. In Figure 21 it can be noted that at the beginning of operation the
duty cycle of the half bridge is initially considerably less than 50%, the tank current has
lower peak values and changes sign every half-cycle, while the DC voltage across the
resonant capacitor reaches the steady-state. The device goes to normal operation after
approximately 50 µs from the first switching cycle. This transition is almost seamless and
just a small perturbation of the tank current can be observed.
Figure 20. Startup at 115 Vac - full load
CH1: HB voltage
CH3: CSS
4.2
CH2: LVG
CH4: ISEN
AM11413v1
Figure 21. Startup at full load - detail
CH1: HB voltage
CH3: CSS
CH2: LVG
CH4: ISEN
AM11414v1
Burst mode operation at light load
In Figure 22 some burst mode pulses are captured during 250 mW load operation. The
burst pulses are very narrow and their period is quite long, therefore the resulting equivalent
switching frequency is very low, ensuring high efficiency. The resulting output voltage ripple
during burst mode operation is about 200 mV peak-to-peak.
In Figure 23 the detail of the burst is reported: the first initial pulse is shorter than the
following ones avoiding the typical high current peak at half bridge operation restarting, due
to the recharging or the resonant capacitor. The maximum operating frequency of the half
bridge, set by the resistor R34 in series to the optocoupler, is around 77 kHz.
DocID022604 Rev 3
21/41
41
Functional check
AN4027
Figure 22. Pout = 250 mW operation
CH1: HB voltage
CH3: STBY
CH2: LVG
CH4: Vout (AC coupl.)
AM11624v1
Figure 23. Pout = 250 mW operation - detail
CH1: HB voltage
CH3: STBY
CH2: LVG
CH4: Res. tank current
AM11625v1
In Figure 24 and Figure 25 the transitions from full load to no load and vice versa have been
checked. As seen in the images, both transitions are clean and there isn't any output voltage
dip.
Figure 24. Transition full load to no load at
115 Vac - 60 Hz
CH1: LVG pin
CH2: PFC gate
CH3: Output voltage CH4: Output current
4.3
AM11626v1
Figure 25. Transition no load to full load at
115 Vac - 60 Hz
CH1: LVG pin
CH2: PFC gate
CH3: Output voltage CH4: Output current
AM11627v1
Overcurrent and short-circuit protection
The L6699 is equipped with a current sensing input (pin 6, ISEN) and a dedicated
overcurrent management system. The current flowing in the resonant tank is detected and
the signal is fed into the ISEN pin. It is internally connected to a first comparator, referenced
to 0.8 V, and to a second comparator referenced to 1.5 V. If the voltage externally applied to
the pin exceeds 0.8 V, the first comparator is tripped causing an internal switch to be turned
on and to discharge the soft-start capacitor CSS.
Under output short-circuit, this operation results in a nearly constant peak primary current.
With the L6699, the board designer can externally program the maximum time that the
22/41
DocID022604 Rev 3
AN4027
Functional check
converter is allowed to run overloaded or under short-circuit conditions. Overloads or shortcircuits lasting less than the set time do not cause any other action, therefore providing the
system with immunity to short duration phenomena. If, instead, the overload condition keeps
going, a protection procedure is activated that shuts down the L6699 and, in the case of
continuous overload/short-circuit, results in continuous intermittent operation with a user
defined duty cycle. This function is realized with the DELAY pin (pin 2), by means of a
capacitor C45 and the parallel resistor R24 connected to ground. As the voltage on the
ISEN pin exceeds 0.8 V, the first OCP comparator, in addition to discharging CSS, turns on
an internal 150 µA current generator that, via the DELAY pin, charges C45. When the
voltage on C45 is 3.5 V, the L6699 stops switching and the PFC_STOP pin is pulled low.
Also the internal generator is turned off, so that C45 is now slowly discharged by R24. The
IC restarts when the voltage on C45 becomes lower than 0.3 V.
Additionally, if the voltage on the ISEN pin reaches 1.5 V for any reason (e.g. transformer
saturation), the second comparator is triggered, the L6699 shuts down and C45 is charged
to 3.5 V. Even in this case, the operation is resumed once the voltage on C45 drops below
0.3 V.
In Figure 26 a dead short-circuit event has been captured. In this case the overcurrent
protection is triggered by the second comparator referenced at 1.5 V which immediately
stops switching by the L6699 and discharging of the soft-start capacitor; at the same time
the capacitor connected to the DELAY pin (#2) begins charging up to 3.5 V (typ.). Once the
voltage on the DELAY pin reaches 3.5 V, the L6699 stops charging the delay capacitor
(C45) and the L6699 operation is resumed once the DELAY pin (#2) voltage decays to 0.3 V
(typ.) by the parallel resistor (R24), via a soft-start cycle. If the short-circuit condition is
removed, the converter again starts operation, otherwise if the short is still there, the
converter operation results in an intermittent operation (Hiccup mode) with a narrow
operating duty cycle of the converter, in order to prevent overheating of power components,
as can be noted in Figure 28.
In Figure 27 details of peak current with short-circuit occurring is shown. It is possible to see
the ZVS correct operation by the half bridge MOSFETs.
Figure 26. Short-circuit at full load
CH1: HB voltage
CH3: CSS
CH2: DELAY
CH4: ISEN
AM11628v1
Figure 27. Short-circuit at full load – detail
CH1: HB voltage
CH3: CSS
DocID022604 Rev 3
CH2: DELAY
CH4: ISEN
AM11629v1
23/41
41
Functional check
.
AN4027
Figure 28. Short-circuit - hiccup mode
CH1: HB voltage
CH3: CSS
4.4
CH2: DELAY
CH4: ISEN
AM11630v1
Anti-capacitive mode protection
The EVL6699-150W-SR demonstration board has been designed in such a way that the
system does not work in capacitive mode during normal operation or failure conditions. As
seen in Figure 27, even in dead short condition the LLC operates correctly in the inductive
region, the same correct operation happens during load or input voltage transients.
Normally, the resonant half bridge converter operates with the resonant tank current lagging
behind the square-wave voltage applied by the half bridge leg, like a circuit having a
reactance of an inductive nature. In this way the applied voltage and the resonant current
have the same sign at every transition of the half bridge, which is a necessary condition in
order for soft-switching to occur (zero-voltage switching, ZVS at turn-on for both MOSFETs).
Therefore, should the phase relationship reverse, i.e. the resonant tank current leads the
applied voltage, such as in circuits having a capacitive reactance, soft-switching would be
lost. This is termed capacitive mode operation and must be avoided because of its
significant drawbacks:
24/41
1.
Both MOSFETs feature hard-switching at turn-on, like in conventional PWM-controlled
converters (see Figure 14). The associated capacitive losses may be considerably
higher than the total power normally dissipated under “soft-switching” conditions and
this may easily lead to their overheating, as heatsinking is not usually sized to handle
this abnormal condition.
2.
The body diode of the MOSFET just switched off conducts current during the deadtime
and its voltage is abruptly reversed by the other MOSFET turned on (see Figure 14).
Therefore, the conducting body diode (which does not generally have great reverse
recovery characteristics) keeps its low impedance until it recovers, and so originating
a condition equivalent to a shoot-through of the half bridge leg. This is a potentially
destructive condition (see point 3) and causes additional power dissipation due to the
current and voltage of the conducting body diode simultaneously high during part of its
recovery.
3.
There is an extremely high reverse dv/dt (many tens of V/ns!) experienced by the
conducting body diode at the end of its recovery with the other MOSFET turned on.
This dv/dt may exceed the rating of the MOSFET and lead to an immediate failure
because of the second breakdown of the parasitic BJT intrinsic in its structure. If
DocID022604 Rev 3
AN4027
Functional check
a MOSFET is hot, the turn-on threshold of its parasitic BJT is lower, this dv/dt-induced
failure is then far more likely.
4.
When either MOSFET is turned on, the other one can be parasitically turned on too, if
the current injected through its Cgd and flowing through the gate driver's pull-down is
large enough to raise the gate voltage close to the turn-on threshold. This would be
a lethal shoot-through condition for the half bridge leg.
5.
The recovery of the body diodes generates large and energetic negative voltage spikes
because of the unavoidable parasitic inductance of the PCB subject to its di/dt. These
are coupled to the OUT pin and may damage the L6699.
6.
There is a large common-mode EMI generation that adversely affects EMC.
Resonant converters work in capacitive mode when their switching frequency falls below
a critical value that depends on the loading conditions and the input-to-output voltage ratio.
They are especially prone to run in capacitive mode when the input voltage is lower than the
minimum specified and/or the output is overloaded or short-circuited. Designing a converter
so that it never works in capacitive mode, even under abnormal operating conditions, is
certainly possible but this may pose unacceptable design constraints in some cases.
To prevent the severe drawbacks of capacitive mode operation, while enabling a design that
needs to ensure Inductive mode operation only in the specified operating range, neglecting
abnormal operating conditions, the L6699 provides the capacitive mode detection function.
The L6699 monitors the phase relationship between the tank current circuit sensed on the
ISEN pin and the voltage applied to the tank circuit by the half bridge, checking that the
former lags behind the latter (inductive mode operation). If the phase-shift approaches zero,
which is indicative of impending capacitive mode operation, the monitoring circuit activates
the anti-capacitive mode protection procedure so that the resulting frequency rise keeps the
converter away from that dangerous condition. Also in this case, the DELAY pin is activated,
so that the OLP function, if used, is eventually tripped, causing intermittent operation and
reducing thermal stress.
If the phase relationship reverses abruptly (which may happen in the case of dead short at
the converter output), the L6699 is stopped immediately, the soft-start capacitor CSS is
totally discharged and a new soft-start cycle is initiated after 50 µs idle time. During this idle
period the PFC_STOP pin is pulled low to stop the PFC stage as well.
DocID022604 Rev 3
25/41
41
Thermal map
5
AN4027
Thermal map
In order to check the design reliability, a thermal mapping by means of an IR camera was
done. Below, the thermal measurements of the board, component side, at nominal input
voltage are shown. Some pointers, visible on the images, have been placed across key
components or components showing high temperature. The ambient temperature during
both measurements was 26 °C.
Figure 29. Thermal map at 115 Vac - 60 Hz - full load
Figure 30. Thermal map at 230 Vac - 50 Hz - full load
26/41
DocID022604 Rev 3
AN4027
Thermal map
Table 6. Thermal maps reference points
Point
Reference
Description
A
D1
Bridge rectifier
B
L1
EMI filtering inductor
C
L2
PFC inductor
D
Q8
ICs supply regulator
E
D4
PFC output diode
F
R6
Inrush limiting NTC resistor
G
Q4
Resonant low-side MOSFET
H
T1
Resonant power transformer
I
Q501
SR MOSFET
DocID022604 Rev 3
27/41
41
Conducted emission pre-compliance test
6
AN4027
Conducted emission pre-compliance test
The following figures represent the average measurement of the conducted emission at full
load and nominal mains voltages. The EN55022 Class-B limit relevant to average
measurements is indicated in red on the diagrams. In all test conditions the measurements
are significantly below the limits.
Figure 31. CE average measurement at 115 Vac - Figure 32. CE average measurement at 230 Vac 60 Hz and full load
50 Hz and full load
AM11633v1
28/41
DocID022604 Rev 3
AM11634v1
AN4027
7
Bill of material
Bill of material
Table 7. EVL6699-150W-SR demonstration board: motherboard bill of material
Des.
Part number /
part value
Description
Supplier
Case
C1
470 nF - X2
X2 - film cap - B32922C3474K
EPCOS
9.0 × 18.0 p 15 mm
C2
2.2 nF - Y1
Y1 safety cap. CD12-E2GA222MYGSA
EPCOS
p10 mm
C3
2.2 nF - Y1
Y1 safety cap. CD12-E2GA222MYGSA
EPCOS
p10 mm
C4
470 nF - X2
X2 - film cap. B32922C3474K
EPCOS
9.0 × 18.0 p 15 mm
C5
470 nF - 520 V
520 V - film cap. - B32673Z5474K
EPCOS
7.0 x 26.5 p 22.5 mm
C6
330 nF
50 V CERCAP - general purpose
AVX
SMD 0805
C7
100 nF
100 V CERCAP - general purpose
AVX
PTH
C8
10 µF - 50 V
Aluminium Elcap - YXF series - 105 °C
Rubycon
Dia. 5.0 x 11 mm
C9
100 µF - 450 V
Aluminium Elcap - UPZ series - 105 °C
Nichicon
Dia. 18 x 32 mm
C10
1 nF
50 V CERCAP - general purpose
AVX
SMD 0805
C11
2.2 nF
50 V CERCAP - general purpose
AVX
SMD 0805
C12
1 µF
25 V CERCAP - general purpose
AVX
SMD 0805
C13
680 nF
25 V CERCAP - general purpose
AVX
SMD 1206
C14
68 nF
50 V CERCAP - general purpose
AVX
SMD 0805
C15
47 µF - 50 V
Rubycon
Dia. 6.3 x 11 mm
C16
2.2 nF
50 V CERCAP - general purpose
AVX
SMD 1206
C17
330 pF
50 V - 5 % - C0G - CERCAP
AVX
SMD 0805
C18
4.7 µF
25 V CERCAP - general purpose
AVX
SMD 1206
C19
100 nF
50 V CERCAP - general purpose
AVX
SMD 1206
C20
2.2 nF - Y1
Y1 safety cap. CD12-E2GA222MYGSA
EPCOS
p10mm
C21
2.2 nF - Y1
Y1 safety cap. CD12-E2GA222MYGSA
EPCOS
p10mm
C22
220 pF
50 V CERCAP - general purpose
AVX
SMD 0805
C23
10 nF
50 V CERCAP - general purpose
AVX
SMD 0805
C24
220 µF - 50 V
Rubycon
Dia. 10 x 16 mm
C25
1.5 nF
AVX
SMD 0805
C26
10 µF - 50 V
Rubycon
Dia. 5.0 x 11 mm
C27
220 pF - 630 V
630 V CERCAP - GRM31A7U2J221JW31
Murata
SMD 1206
C28
22 nF
1 KV - film cap. B32652A223K
EPCOS
5.0 x 18.0 p 15 mm
C29
470 µF - 16 V
16 V OSCON CAP 16SEPC470M
Sanyo
Dia. 10 x 13 p 5 mm
C30
470 µF - 16 V
16 V OSCON CAP 16SEPC470M
Sanyo
Dia. 10 x 13 p 5 mm
C32
470 nF
50 V CERCAP - general purpose
AVX
SMD 0805
C33
1.5 nF
50 V CERCAP - general purpose
AVX
SMD 0805
Aluminium Elcap - YXF series - 105 °C
Aluminium Elcap - YXF series - 105 °C
50 V CERCAP - general purpose
Aluminium Elcap - YXF series - 105 °C
DocID022604 Rev 3
29/41
41
Bill of material
AN4027
Table 7. EVL6699-150W-SR demonstration board: motherboard bill of material (continued)
Des.
Part number /
Description
part value
Supplier
Case
C34
100 nF
50 V CERCAP - general purpose
AVX
SMD 0805
C36
1 µF - 50 V
50 V CERCAP - general purpose
AVX
SMD 1206
C37
470 µF-16 V
16 V OSCON CAP 16SEPC470M
Sanyo
Dia. 10 x 13 p 5 mm
C38
100 nF
50 V CERCAP - general purpose
AVX
SMD 0805
C39
100 nF
50 V CERCAP - general purpose
AVX
SMD 0805
C40
100 nF
50 V CERCAP - general purpose
AVX
SMD 1206
C42
100 nF
50 V CERCAP - general purpose
AVX
SMD 0805
C43
4.7 nF
50 V CERCAP - general purpose
AVX
SMD 0805
C44
1.5 nF
50 V CERCAP - general purpose
AVX
SMD 0805
C45
220 nF
25 V CERCAP - general purpose
AVX
SMD 0805
C47
1 nF
50 V CERCAP - general purpose
AVX
SMD 0805
C48
1 nF
50 V CERCAP - general purpose
AVX
SMD 0805
C49
470 µF-16 V
16 V OSCON CAP 16SEPC470M
Sanyo
Dia. 10 x 13 p 5 mm
C50
470 µF-16 V
16 V OSCON CAP 16SEPC470M
Sanyo
Dia. 10 x 13 p 5 mm
C51
100 nF
50 V CERCAP - general purpose
AVX
SMD 0805
C52
1 nF
25 V CERCAP - general purpose
AVX
SMD 0805
D1
GBU8J
Single-phase bridge rectifier
Vishay
STYLE GBU
D2
LL4148
High speed signal diode
Vishay
Mini Melf SOD-80
D3
1N4005
General purpose rectifier
Vishay
DO-41
D4
STTH5L06
ST
DO-201
D5
LL4148
High speed signal diode
Vishay
Mini Melf SOD-80
D6
LL4148
High speed signal diode
Vishay
Mini Melf SOD-80
D7
STPS140Z
Power Schottky rectifier
ST
SOD-123
D9
STPS2H100A
Power Schottky diode
ST
SMB
D12
BZV55-C43
Zener diode
Vishay
Mini Melf SOD-80
D14
LL4148
High speed signal diode
Vishay
Mini Melf SOD-80
D17
LL4148
High speed signal diode
Vishay
Mini Melf SOD-80
D18
LL4148
High speed signal diode
Vishay
Mini Melf SOD-80
D19
LL4148
High speed signal diode
Vishay
Mini Melf SOD-80
D20
BZV55-B15
Zener diode
Vishay
Mini Melf SOD-80
D21
LL4148
High speed signal diode
Vishay
Mini Melf SOD-80
F1
FUSE T4A
Fuse 4 A - time lag - 3921400
Littlefuse
8.5 x 4 p. 5.08 mm
HS1
HEAT-SINK
Heatsink for D1, Q1, Q3, Q4
30/41
Ultrafast high-voltage rectifier
DocID022604 Rev 3
DWG
AN4027
Bill of material
Table 7. EVL6699-150W-SR demonstration board: motherboard bill of material (continued)
Des.
Part number /
part value
Description
Supplier
Case
Phoenix
Contact
DWG
J1
MKDS 1,5/ 35,08
J2
FASTON
FASTON - connector
DWG
J3
FASTON
FASTON - connector
DWG
JPX1
JUMPER
Bare copper wire jumper
DWG
L1
2019.0002
Common mode choke - EMI filter
Magnetica
DWG
L2
1975.0004
PFC inductor - 0.31 mH - PQ26/25
Magnetica
DWG
Q1
STF21N65M5
ST
TO-220FP
Q2
BC857C
Vishay
SOT-23
Q3
STF8NM50N
N-channel Power MOSFET
ST
TO-220FP
Q4
STF8NM50N
N-channel Power MOSFET
ST
TO-220FP
Q8
BC847C
NPN small signal BJT
Vishay
SOT-23
Q9
BC847C
NPN small signal BJT
Vishay
SOT-23
R1
6.8 M
SMD STD film res. - 1/4 W - 5% - 250 ppm/°C
Vishay
SMD 1206
R2
5.6 M
SMD STD film res. - 1/4 W - 5% - 250 ppm/°C
Vishay
SMD 1206
R3
2.2 M
SMD STD film res. - 1/4 W - 1% - 100 ppm/°C
Vishay
SMD 1206
R5
75 
SMD STD film res. - 1/4 W - 5% - 250 ppm/°C
Vishay
SMD 1206
R6
NTC 2R5-S237
NTC resistor B57237S0259M000
EPCOS
DWG
R7
2.2 M
SMD STD film res. - 1/4 W - 1% - 100 ppm/°C
Vishay
SMD 1206
R8
2.2 M
SMD STD film res. - 1/4 W - 1% - 100 ppm/°C
Vishay
SMD 1206
R9
160 K
SMD STD film res. - 1/8 W - 1% - 100 ppm/°C
Vishay
SMD 0805
R10
56 K
SMD STD film res. - 1/8 W - 1% - 100 ppm/°C
Vishay
SMD 0805
R11
2.2 M
SMD STD film res. - 1/4 W - 1% - 100 ppm/°C
Vishay
SMD 1206
R12
2.2 M
SMD STD film res. - 1/4 W - 1% - 100 ppm/°C
Vishay
SMD 1206
R13
9.1 K
SMD STD film res. - 1/4 W - 1% - 100 ppm/°C
Vishay
SMD 1206
R14
100 K
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R15
56 K
SMD STD film res. - 1/4 W - 1% - 100 ppm/°C
Vishay
SMD 1206
R16
2.7 K
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R17
2.2 M
SMD STD film res. - 1/4 W - 1% - 100 ppm/°C
Vishay
SMD 1206
R18
82 K
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R19
56 K
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R20
33 
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R21
22 
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R22
0.22 
AKANEOHM
PTH
PCB term. block, screw conn., pitch 5 mm - 3 W
N-channel Power MOSFET
PNP small signal BJT
RSMF1TB - metal film res. - 1 W - 2% 250 ppm/°C
DocID022604 Rev 3
31/41
41
Bill of material
AN4027
Table 7. EVL6699-150W-SR demonstration board: motherboard bill of material (continued)
Des.
Part number /
part value
Description
Supplier
Case
AKANEOHM
PTH
R23
0.22 
RSMF1TB - metal film res. - 1 W - 2% 250 ppm/°C
R24
1 M
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R25
56 
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R26
1 M
SMD STD film res. - 1/8 W - 1% - 100 ppm/°C
Vishay
SMD 0805
R27
470 
SMD STD film res. - 1/4 W - 5% - 250 ppm/°C
Vishay
SMD 1206
R28
33 K
SMD STD film res. - 1/8 W - 1% - 100 ppm/°C
Vishay
SMD 0805
R29
1 K
SMD STD film res. - 1/4 W - 5% - 250 ppm/°C
Vishay
SMD 1206
R30
10 
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R31
20 K
SMD STD film res. - 1/8 W - 1% - 100 ppm/°C
Vishay
SMD 0805
R32
47 
SMD STD film res. - 1/8 W - 5% - 250ppm/°C
Vishay
SMD 0805
R34
8.2 K
SMD STD film res. - 1/8 W - 1% - 100 ppm/°C
Vishay
SMD 0805
R35
180 K
SMD STD film res. - 1/8 W - 1% - 100 ppm/°C
Vishay
SMD 0805
R36
1.8 M
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R37
220 K
SMD STD film res. - 1/4 W - 5% - 250 ppm/°C
Vishay
SMD 1206
R38
56 
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R40
68 
SMD STD film res. - 1/4 W - 5% - 250 ppm/°C
Vishay
SMD 1206
R41
100 
SFR25 axial stand. Film res. - 0.4 W - 5% 250 ppm/°C
Vishay
PTH
R42
1 K
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R43
51 
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R44
6.3 K
SMD STD film res. - 1/4 W - 5% - 250 ppm/°C
Vishay
SMD 1206
R45
3.3 
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R46
100 K
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R48
47 K
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R49
91 K
SMD STD film res. - 1/8 W - 1% - 100 ppm/°C
Vishay
SMD 1206
R50
12 K
SMD STD film res. - 1/8 W - 1% - 100 ppm/°C
Vishay
SMD 0805
R51
91 K
SMD STD film res. - 1/8 W - 1% - 100 ppm/°C
Vishay
SMD 0805
R52
1.5 K
SMD STD film res. - 1/8 W - 1% - 100 ppm/°C
Vishay
SMD 0805
R53
2.2 K
SMD STD film res. - 1/8 W - 1% - 100 ppm/°C
Vishay
SMD 0805
R54
0
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R55
2.7 K
SMD STD film res. - 1/8 W - 1% - 100 ppm/°C
Vishay
SMD 0805
R57
0.02 
SMD current sense resistor - ERJM1WTF2M0U
Panasonic
SMD 2512
R58
100 K
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R59
100 K
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
32/41
DocID022604 Rev 3
AN4027
Bill of material
Table 7. EVL6699-150W-SR demonstration board: motherboard bill of material (continued)
Des.
Part number /
Description
part value
Supplier
Case
R60
10 K
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R63
0
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R64
10 M
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R68
5.6 K
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R69
24 K
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R70
22 K
SMD STD film res. - 1/8 W - 1% - 100 ppm/°C
Vishay
SMD 0805
R71
1 K
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 1206
R72
68 K
SMD STD film res. - 1/8 W - 1% - 100 ppm/°C
Vishay
SMD 0805
R73
22 
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R75
0
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R76
33 K
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R77
1 K
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R78
33 
SMD STD film res. - 1/4 W - 5% - 250 ppm/°C
Vishay
SMD 1206
R79
270 
SMD STD film res. - 1/4 W - 5% - 250 ppm/°C
Vishay
SMD 1206
T1
1860.0069
Magnetica
ETD34
U1
L6563H
High-voltage startup TM PFC controller
ST
SO-16
U2
L6699D
Improved HV resonant controller
ST
SO-16
Resonant power transformer
Table 8. EVL6699-150W-SR demonstration board: daughterboard bill of material
Des.
Part number/
part value
C501
4.7 nF
C502
Description
Supplier
Case
50 V CERCAP - general purpose
Vishay
SMD 0805
100 nF
50 V CERCAP - general purpose
Vishay
SMD 0805
C503
1 µF
50 V CERCAP - general purpose
Vishay
SMD 0805
C504
150 pF
50 V CERCAP - general purpose
Vishay
SMD 0805
C505
150 pF
50 V CERCAP - general purpose
Vishay
SMD 0805
D501
BAS316
Fast switching signal diode
ST
SOD-123
D502
BAS316
Fast switching signal diode
ST
SOD-123
JP501
HEADER 13
13-pin connector
Q501
STL140N4LLF5 N-channel Power MOSFET
ST
PowerFLAT™
Q502
STL140N4LLF5 N-channel Power MOSFET
ST
PowerFLAT™
R501
10 
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R502
10 
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R503
10 
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
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Bill of material
AN4027
Table 8. EVL6699-150W-SR demonstration board: daughterboard bill of material (continued)
Des.
Part number/
part value
R504
150 k
R505
Supplier
Case
SMD STD film res. - 1/8 W - 1% - 100 ppm/°C
Vishay
SMD 0805
33 k
SMD STD film res. - 1/8 W - 1% - 100 ppm/°C
Vishay
SMD 0805
R506
330 
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
R507
330 
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
RX1
0
SMD STD film res. - 1/8 W - 5% - 250 ppm/°C
Vishay
SMD 0805
U501
SRK2000A
ST
SO8
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Description
SR smart driver for LLC resonant converter
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PFC coil specification
8
PFC coil specification
8.1
General description and characteristics
8.2
8.3

Application type: consumer, home appliance

Transformer type: open

Coil former: vertical type, 6 + 6 pins

Max. temp. rise: 45 ºC

Max. operating ambient temperature: 60 ºC

Mains insulation: n.a.

Unit finishing: varnished.
Electrical characteristics

Converter topology: boost, transition mode

Core type: PQ26/25-PC44 or equivalent

Min. operating frequency: 40 kHz

Typical operating frequency: 120 kHz

Primary inductance: 310 µH ± 10% at 1 kHz - 0.25 V (a)

Peak current: 5.6 Apk.
Electrical diagram and winding characteristics
Figure 33. PFC coil electrical diagram
5
11
9
3
AM11635v1
a. Measured between pins #5 and #9.
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PFC coil specification
AN4027
Table 9. PFC coil winding data
Pins
Windings
RMS current
Number of turns
Wire type
11 - 3
AUX
0.05 ARMS
5
 0.28 mm – G2
5-9
Primary
2.3 ARMS
50
50x 0.1 mm – G1
8.4
Mechanical aspect and pin numbering

Maximum height from PCB: 30 mm

Coil former type: vertical, 6 + 6 pins (pins 1, 2, 4, 6, 7, 10, 12 are removed)

Pin distance: 3.81 mm

Row distance: 25.4 mm

External copper shield: not insulated, wound around the ferrite core and including the
coil former. Height is 8 mm. Connected to pin #3 by a soldered solid wire.
Figure 34. PFC coil mechanical aspect
AM11636v1
8.5
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Manufacturer

Magnetica - Italy

Inductor P/N: 1975.0004.
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AN4027
Transformer specifications
9
Transformer specifications
9.1
General description and characteristics
9.2
9.3

Application type: consumer, home appliance

Transformer type: open

Coil former: horizontal type, 7 + 7 pins, two slots

Max. temp. rise: 45 ºC

Max. operating ambient temperature: 60 ºC

Mains insulation: acc. to EN60065.
Electrical characteristics

Converter topology: half bridge, resonant

Core Type: ETD34-PC44 or equivalent

Min. operating frequency: 60 kHz

Typical operating frequency: 100k Hz

Primary inductance: 1000 µH ± 10% at 1 kHz - 0.25 V(b)

Leakage inductance: 100 µH ± 10% at 100 kHz - 0.25 V(c).
Electrical diagram and winding characteristics
Figure 35. Transformer electrical diagram
2
8
9
10
11
12
4
6
13
14
7
AM11637v1
b. Measured between pins 2 - 4.
c.
Measured between pins 2 - 4 with only half secondary winding shorted at a time.
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Transformer specifications
AN4027
Table 10. Transformer winding data
Pins
Winding
RMS current
Number of turns
Wire type
2-4
Primary
1 ARMS
34
30 x  0.1 mm – G1
(1)
8.5 ARMS
2
90 x  0.1 mm – G1
9 - 10
(1)
SEC-1B
8.5 ARMS
2
90 x  0.1 mm – G1
10 - 13
SEC-2A(1)
8.5 ARMS
2
90 x  0.1 mm – G1
12 - 14
(1)
8.5 ARMS
2
90 x  0.1 mm – G1
0.05 ARMS
3
 0.28 mm – G2
8 - 11
6-7
SEC-1A
SEC-2B
(2)
AUX
1. Secondary windings A and B are in parallel.
2. Aux winding is wound on top of primary winding.
9.4
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Mechanical aspect and pin numbering

Maximum height from PCB: 30 mm

Coil former type: horizontal, 7 + 7 pins (pins #3 and #5 are removed)

Pin distance: 5.08 mm

Row distance: 25.4 mm.
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Transformer specifications
Figure 36. Transformer overall drawing
9.5
Manufacturer

Magnetica - Italy

Transformer P/N: 1860.0069.
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Revision history
10
AN4027
Revision history
Table 11. Document revision history
Date
Revision
19-Jul-2012
1
Initial release.
18-Apr-2013
2
Updated Table 8: EVL6699-150W-SR demonstration board:
daughterboard bill of material.
3
Replaced “SRK2000” by “SRK2000A” in main title 12 V - 150 W
resonant converter with synchronous rectification using the
L6563H, L6699 and SRK2000A on page 1, Section 1 on page
6, Section 4 on page 18, and Section 7 on page 29.
Updated Section : Introduction on page 1.
Updated Table 1 on page 6 (updated “Parameters” and
“Values”).
Updated Figure 2 on page 8 (replaced by new figure).
Updated Equation 2 on page 8 (updated Equation 2 and text
above).
Updated Equation 3 on page 9 (updated Equation 3 and text
below).
Updated Figure 3 on page 12 (updated R72, Q1, and U501
parts, minor modifications).
Updated Table 2 on page 13 (updated “Pin” rows of “No load”,
added rows with 10% load conditions).
Updated Figure 4 on page 13 (replaced by new figure).
Updated Table 3 on page 14 (updated title, header, added
“Efficiency at 10% load” row, updated limits of “No load input
power”).
Updated Table 7 on page 29 (updated “Part number/part value”
of “C18”, updated units throughout Table 7).
Updated Table 8 on page 33 (updated “Description” of “C27”,
“C29”, “C30”, “C37”, “C49”, “C50”, “Part number/part value” of
“R72” and “U501” items, updated units throughout Table 8).
Minor modifications throughout document.
07-Apr-2014
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Changes
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