dm00071253

AN4214
Application note
High power factor flyback converter using the L6564
Harjeet Singh
Introduction
This application note describes the example of single stage high power factor (HPF) flyback
topology using ST’s L6564 PFC controller. The L6564 is a current mode PFC controller
operating in transition mode (TM). The highly linear multiplier, along with a special
correction circuit that reduces crossover distortion of the mains current, allows wide range
mains operation with an extremely low THD, even over a large load range. The main
drawback of such flyback topology with HPF is that it has significant magnitude of twice the
mains frequency ripple at output DC voltage because there is no electrolytic capacitor after
bridge rectification. But there are some applications like lighting for LED driving, battery
chargers, where ripple voltage is not a big concern, since in these applications the loads are
mostly constant-current driven with acceptable ripple or any kind of load which is powered
through followed DC-DC downstream converters connected to output of HPF flyback.
The output voltage is controlled by means of a voltage mode error amplifier and an accurate
(1% at Tj = 25 °C) internal voltage reference. The loop stability is optimized by the voltage
feedforward function (1/V2 correction), which in this IC uses a proprietary technique that
considerably improves line transient response as well in case of both drops and surges
(“bidirectional”) of the mains.
In addition to overvoltage protection being capable of controlling the output voltage in the
PFC stage during transient conditions, the IC also provides protection against feedback loop
failures or erroneous settings. The feature is quite useful in case of flyback operation to
detect output voltage for any primary auxiliary winding and trigger the protection to
shutdown the converter in case output voltage exceeds the nominal value.
Other on-board protection functions allow brownout conditions and magnetic saturation to
be safely handled. The brownout is sensed through the MULT pin to shut down the
converter in case the input mains supply drops below the minimum operating voltage level.
The L6564 main features are:
 Fast “bidirectional” input voltage feedforward (1/V2 correction)
 Accurate adjustable output overvoltage protection
 Protection against feedback loop disconnection (latched shutdown)
 Inductor saturation protection
 AC brownout detection
 Low (100 µA) start-up current
 6 A max. operating bias current
 1% (at TJ = 25 °C) internal reference voltage
 -600/+800 mA totem pole gate driver with active pull-down during UVLO
 SSOP10 package
January 2015
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www.st.com
37
Contents
AN4214
Contents
1
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2
SMPS description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1
PFC_OK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.1
PFC_OK function in PFC operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.2
PFC_OK function in flyback operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.3
VFF pin and brownout function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3
Basic specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4
Transformer construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5
Test results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6
Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.1
Mains voltage and input current waveforms . . . . . . . . . . . . . . . . . . . . . . . 14
6.2
Output load current waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.3
Steady state switching waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7
Short-circuit test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8
No load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
9
Harmonics measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
10
Schematic of SMPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
11
Bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
12
CVCC controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
13
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
14
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
2/37
DocID023991 Rev 1
AN4214
List of tables
List of tables
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Basic specifications of SMPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Transformer specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Winding details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Test results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
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37
List of figures
AN4214
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.
Figure 37.
Figure 38.
4/37
Block diagram of L6564 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Output voltage setting, OVP and FFP functions: internal block diagram . . . . . . . . . . . . . . . 7
Input OVP protection network to bias PFC_OK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Voltage feedforward: squarer-divider (1/V2) block diagram and transfer characteristic . . . . 9
L6562A and L6564 comparison (package and features) . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Transformer construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Current THD vs. mains voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Power factor vs. mains voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Full load efficiency vs. mains voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Ch: 4-input voltage; Ch: 2-input current waveforms at 140 Vac . . . . . . . . . . . . . . . . . . . . . 14
Ch: 4-input voltage; Ch: 2-input current waveforms at 190 Vac . . . . . . . . . . . . . . . . . . . . . 15
Ch: 4-input voltage; Ch: 2-input current waveforms at 220 Vac . . . . . . . . . . . . . . . . . . . . . 15
Ch: 4-input voltage; Ch: 2-input current waveforms at 265 Vac . . . . . . . . . . . . . . . . . . . . . 16
Ch: 2-output load current waveform at 220 Vac pk-pk current ripple = 112 mA . . . . . . . . . 17
Ch: 4-drain-source voltage; Ch: 1-drain current; Ch: 2-COMP at 140 Vac . . . . . . . . . . . . . 18
Ch: 4-drain-source voltage; Ch: 1-drain current; Ch: 2-COMP at 140 Vac (zoom view) . . . 18
Ch: 4-drain-source voltage; Ch: 1-drain current; Ch: 2-COMP at 230 Vac . . . . . . . . . . . . . 19
Ch: 4-drain-source voltage; Ch: 1-drain current; Ch: 2-COMP at 230 Vac (zoom view) . . . 19
Ch: 4-drain-source voltage; Ch: 1-drain current; Ch: 2-COMP at 265 Vac . . . . . . . . . . . . 20
Ch: 4-drain-source voltage; Ch: 1-drain current; Ch: 2- COMP at 265 Vac (zoom view) . . 20
Output short-circuit at 140 Vac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Output short-circuit at 140 Vac (zoom view 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Output short-circuit at 140 Vac (zoom view 2). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Output short-circuit at 230 Vac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Output short-circuit at 230 Vac (zoom view 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Output short-circuit at 230 Vac (zoom view 2). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Output short-circuit at 265 Vac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Output short-circuit at 265 Vac (zoom view 1). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Output short-circuit at 265 Vac (zoom view 2). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
No load waveforms at 140 Vac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
No load waveforms at 265 Vac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Current THD at 150 Vac mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Current THD at 190 Vac mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Current THD at 230 Vac mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Current THD at 265 Vac mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Schematic of SMPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
SEA05 internal circuit and its application in flyback topology . . . . . . . . . . . . . . . . . . . . . . . 34
SEA05 package and pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
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AN4214
Block diagram
Block diagram
Figure 1. Block diagram of L6564
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5/37
37
SMPS description
2
AN4214
SMPS description
The main feature of this converter is that the input current is almost in phase with the mains
voltage, therefore the power factor is close to unity and hence the low current harmonics.
This is achieved using the L6564 TM PFC controller, which shapes the input current as
a sine wave in phase with the mains voltage. The power supply utilizes a typical flyback
converter topology, using a transformer to provide the required insulation between the
primary and secondary side. The converter is connected after the mains rectifier and the
capacitor filter, which in this case is quite small to prevent damage to the shape of the input
current. The flyback switch is represented by the power MOSFET M1, and driven by the
L6564.
At startup, the L6564 is powered by the VCC capacitor (C16), which is charged via resistors
R4 and R8. As the capacitor C16 charges to the turn-on threshold of the L6564 (typically at
12 V), the transformer T1 auxiliary winding (pins 5-6) generates the VCC voltage, rectified
by D8 and R13, that powers the L6564 during normal operation. R12 is also connected to
the auxiliary winding to provide the transformer demagnetization signal to the L6564 ZCD
pin, turning on the MOSFET at any switching cycle. The MOSFET used is the STP7N80K5,
a ST's K5 high voltage MOSFET series device housed in a TO-220 package, and needing
only a small heat sink. The transformer is layer type, using a standard ferrite size ER28. The
flyback reflected voltage is close to 180 V, providing enough room for the leakage
inductance voltage spike still within the reliability margin of the MOSFET even at 300 Vac
input.
The RCD snubber circuit using R5, C5 and D6 clamps the peak of the leakage inductance
voltage spike at MOSFET turn-off. Resistor R3 is usually inserted in series with subbing
capacitor C5 to kill the spike and reduces further the EMI generated due to leakage spikes.
The resistors R33 and R34 sense the current flowing into the transformer primary side.
Once the signal at the current sense pin has reached the level programmed by the internal
multiplier of the L6564, the MOSFET turns off. The divider R11, R14 and R18 provides the
L6564 multiplier pin with instantaneous voltage information which is used to modulate the
current flowing into the transformer primary side. C17 is a small noise suppression
capacitor, of course the purpose of this capacitor is to prevent disturbance to the actual
sinusoidal mains information.
The output regulation is done by means of an isolated voltage loop by the optocoupler U2,
and using an inexpensive TL431 to drive the optocoupler. For an LED driving application,
additional constant current drive circuitry using the SEA05 can be implemented as
described in the schematic, whereas the current signal is detected by sensing resistors R9,
R10. The opto-transistor modulates the input voltage of the L6564 internal amplifier, thus
closing the voltage loop. The output rectifier is a fast recovery type, selected according to its
maximum reverse voltage, forward voltage drop and power dissipation. A small LC filter is
added on the output, filtering the high frequency ripple.
Compared to the L6562A (8-pin TM PFC controller), the L6564 has some additional
features and hence there is additional circuitry incorporated in the schematic for utilizing the
features of the L6564. The L6564 also has two additional pins: VFF and PFC_OK. The
functions of these pins are described in the following paragraphs.
6/37
DocID023991 Rev 1
AN4214
SMPS description
2.1
PFC_OK
2.1.1
PFC_OK function in PFC operation
PFC pre-regulator output voltage monitoring/disable function: This pin senses the
output voltage of the PFC pre-regulator through a resistor divider and is used for protection
purposes. If the voltage on the pin exceeds 2.5 V the IC stops switching and restarts as the
voltage on the pin falls below 2.4 V. However, if the voltage of the INV pin falls 40 mV below
that of the pin PFC_OK, a feedback failure is assumed. In this case the device is latched off
due to feedback failure protection (FFP). Normal operation can be resumed only by cycling
VCC, bringing its value lower than 6 V before moving up to the turn-on threshold. If the
voltage on this pin is brought below 0.23 V, the IC is shut down. To restart the IC the voltage
on the pin must go above 0.27 V. This can also be used as a remote on/off control input.
Referring to the circuit portion below, R3 and R4 composes the network to activate PFC
output overvoltage shutdown.
Figure 2. Output voltage setting, OVP and FFP functions: internal block diagram
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2.1.2
PFC_OK function in flyback operation
The same pin can be also be used in case of flyback converter to shut down the converter in
case of either input overvoltage or output overvoltage. For input overvoltage protection, one
can bias the pin using resistor divider network at rectified DC voltage to activate input
overvoltage protection at the required mains OVP level. Referring to the circuit portion
below, R3, R4 composes the network to activate mains overvoltage shutdown, where the
small capacitor C2 is used to average the DC value of sensing voltage at the PFC_OK pin.
In the schematic, the biasing components R2, R6, R7 and R22 comprise the input OVP
detection circuit. The divider ratio is selected to provide 2.5 V at required mains OVP level.
If output overvoltage protection is preferred instead of mains OVP, we can utilize the
auxiliary winding output used to provide the operating voltage to the controller as well as
demagnetization input to ZCD. Since we get the reflection of output voltage at auxiliary
output supply, we can simply tap the signal for PFC_OK which is programmed to 2.5 V using
DocID023991 Rev 1
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SMPS description
AN4214
the resistor divider network at the desired output OVP. This is achieved using resistor divider
network R5 and R4 at auxiliary output supply. In the schematic (see Figure 36 on page 30)
we have implemented an input OVP protection network to bias PFC_OK.
Figure 3. Input OVP protection network to bias PFC_OK
2.1.3
VFF pin and brownout function
This is second input to the multiplier block for 1/V² function. A capacitor and a parallel
resistor must be connected from this pin to GND. They complete the internal peak-holding
circuit that derives the information on the RMS mains voltage. The voltage at this pin, a DC
level equal to the peak voltage on the pin MULT (3), compensates the control loop gain
dependence on the mains voltage. The variation of internal current reference signal VCSX
versus the mains voltage level detected at MULT input (VFF = VMULT) is shown in the
graph in Figure 4. This is the last signal which is compared with the error signal to output the
required gate signal ON time. Never connect the pin directly to GND, but with a resistor
ranging from 100 kΩ (minimum) to 2 MΩ (maximum). This pin is internally connected to
a comparator in order to provide the brownout (AC mains under voltage) protection.
A voltage below 0.8 V shuts down (not latched) the IC and brings its consumption to
a considerably lower level. The IC restarts as the voltage at this pin goes above 0.88 V.
Note:
8/37
This is one of the important features of the L6564 where we can manage the overload
condition and prevent excessive current from flowing through the input section at worst low
mains operating condition. So as the mains voltage drops below a programmed level, the IC
stops as the VFF pin detects the brownout level.
DocID023991 Rev 1
AN4214
SMPS description
Figure 4. Voltage feedforward: squarer-divider (1/V2) block diagram and transfer
characteristic
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Figure 5. L6562A and L6564 comparison (package and features)
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The L6564 is the same as the L6562A, but with the followings additional features:

Brownout protection: prevents bridge inductor and MOSFET damage

Inductor saturation protection: prevents MOSFET damage

Feedback disconnection protection: prevents bulk capacitor burn

Improved noise immunity: easier PCB layout

Voltage feedforward: high line/load transient rejection

Remote ON/OFF control: to easy communicate with PWM stage
DocID023991 Rev 1
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Basic specifications
3
AN4214
Basic specifications
Table 1. Basic specifications of SMPS
Parameters
Limits
Rated input voltage range
190 - 265 Vac
Minimum voltage operation (in case of line sag)
140 Vac
Input overvoltage shutdown
> 275 Vac
Input supply frequency (fL)
47 - 63 Hz
Input / output isolation
Yes, > 2.7 kV
Power factor correction
Yes, > 0.95
THD
< 20%
Nominal output voltage
75 V ± 1.5 V
Load current
0.7 A
No load input power at 230 Vac
(1)
< 0.75 W
Total output power
55 W
Efficiency (full load for wide mains variations)
> 85%
Output voltage pk-pk ripple(2.fL)
< 20%
Topology
Single stage HPF flyback
Maximum ambient temperature
50 C
1. The no load power consumption is measured after removing the resistors used for input OVP (R2, R6, R7).
Table 2. Transformer specification
10/37
Parameters
Limits
Max. output power
Max. 55 W
Primary inductance
0.62 ± 0.01 mH at 50 KHz
Primary side leakage inductance
< 10 µH at 50 KHz
Peak primary current
2.8 A
Average primary current
0.9 A
Saturation current
3.5 A
Operating switching frequency
50 KHz min. to 125 KHz max.
Core size
ER28/17/11
Ferrite material
N87, EPCOS
Bobbin
12 pins, horizontal
Dielectric strength
> 2.7 kV
Approx air gap (central limb)
0.8 mm
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AN4214
Transformer construction
Table 3. Winding details
Winding name
4
Start
Stop
No. of turns
Wire gauge
Order of windings
Np1
3
2
35
4 x 0.25 mm
Bottom
Naux1
5
6
8
0.15 mm
Above Np1
Nsec
12
10
30
7 x 0.2 5 mm
Above Naux
Naux2
8
7
7
0.15 mm
Above Nsec
Np2
2
1
35
4 x 0.25 mm
Topmost
Transformer construction
Figure 6. Transformer construction
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Test results
5
AN4214
Test results
The converter is tested at full load conditions from 140 Vac to 265 Vac and following are the
test results as shown in Table 4.
Table 4. Test results
% efficiency
Ior (mA)(1)
55.00
85.84
122
0.72
54.86
86.91
120
76.1
0.71
54.26
88.51
116
60.23
75.9
0.72
54.27
90.10
112
59.57
75.5
0.71
53.76
90.24
112
%ITHD Pin (W)
Vinac (Vrms)
Arms
PF
Vo (Vdc)
Io (Adc) Po (W)
140
0.449
0.999
5.16
64.08
76.4
0.72
150
0.417
0.999
5.52
63.13
76.2
190
0.321
0.996
9.78
61.30
230
0.263
0.991
13.3
265
0.231
0.973
15.9
1. Ior = load current peak-peak ripple.
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DocID023991 Rev 1
AN4214
Test results
Figure 8. Power factor vs. mains voltage
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Figure 9. Full load efficiency vs. mains voltage
(IILFLHQF\
(IILFLHQF\
9LQDF9UPV
*,3*07
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Waveforms
AN4214
6
Waveforms
6.1
Mains voltage and input current waveforms
The converter is loaded at full load at input mains current is captured at different line
conditions: 140 Vac, 190 Vac, 220 Vac and 265 Vac as shown from Figure 10 to 14.
Figure 10. Ch: 4-input voltage; Ch: 2-input current waveforms at 140 Vac
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Waveforms
Figure 11. Ch: 4-input voltage; Ch: 2-input current waveforms at 190 Vac
Figure 12. Ch: 4-input voltage; Ch: 2-input current waveforms at 220 Vac
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Waveforms
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Figure 13. Ch: 4-input voltage; Ch: 2-input current waveforms at 265 Vac
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6.2
Waveforms
Output load current waveform
The full load current waveform is captured at 220 Vac. The current pattern shows 100 Hz
line ripple reflected at output. The typical peak to peak ripple is 15% of rated load current.
Figure 14. Ch: 2-output load current waveform at 220 Vac pk-pk
current ripple = 112 mA
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Waveforms
6.3
AN4214
Steady state switching waveforms
The converter is powered at full load conditions and typical switching waveforms are
captured as shown from Figure 15 to 20.
Figure 15. Ch: 4-drain-source voltage; Ch: 1-drain current; Ch: 2-COMP at 140 Vac
Figure 16. Ch: 4-drain-source voltage; Ch: 1-drain current; Ch: 2-COMP at 140 Vac
(zoom view)
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Waveforms
Figure 17. Ch: 4-drain-source voltage; Ch: 1-drain current; Ch: 2-COMP at 230 Vac
Figure 18. Ch: 4-drain-source voltage; Ch: 1-drain current; Ch: 2-COMP at 230 Vac
(zoom view)
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Waveforms
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Figure 19. Ch: 4-drain-source voltage; Ch: 1-drain current; Ch: 2-COMP at 265 Vac
Figure 20. Ch: 4-drain-source voltage; Ch: 1-drain current; Ch: 2- COMP at 265 Vac
(zoom view)
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7
Short-circuit test
Short-circuit test
The short-circuit of output terminals of the converter is performed to analyze the safe
operation of the converter in case of overload and short-circuit. The test is performed at
140 Vac, 230 Vac and 265 Vac in order to observe for any malfunction or failure.
In particular the waveforms of drain switching voltage, drain current and Vcc of the device is
observed when attempting the short-circuit.
Looking into figures from 21 to 23, we can notice that there is no stress condition observed
in power as well as control stage. The L6564 enters into protection mode with very low
switching frequency of switching burst and MOSFET is well protected.
Figure 21. Output short-circuit at 140 Vac
&K'UDLQVRXUFHYROWDJH&K'UDLQFXUUHQW&K&203&K9FF
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Short-circuit test
AN4214
Figure 22. Output short-circuit at 140 Vac (zoom view 1)
&K'UDLQVRXUFHYROWDJH&K'UDLQFXUUHQW&K&203&K9FF
*,3
Figure 23. Output short-circuit at 140 Vac (zoom view 2)
&K'UDLQVRXUFHYROWDJH&K'UDLQFXUUHQW&K&203&K9FF
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Short-circuit test
Figure 24. Output short-circuit at 230 Vac
&K'UDLQVRXUFHYROWDJH&K'UDLQFXUUHQW&K&203&K9FF
*
Figure 25. Output short-circuit at 230 Vac (zoom view 1)
&K'UDLQVRXUFHYROWDJH&K'UDLQFXUUHQW&K&203&K9FF
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Short-circuit test
AN4214
Figure 26. Output short-circuit at 230 Vac (zoom view 2)
&K'UDLQVRXUFHYROWDJH&K'UDLQFXUUHQW&K&203&K9FF
*
Figure 27. Output short-circuit at 265 Vac
&K'UDLQVRXUFHYROWDJH&K'UDLQFXUUHQW&K&203&K9FF
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Short-circuit test
Figure 28. Output short-circuit at 265 Vac (zoom view 1)
&K'UDLQVRXUFHYROWDJH&K'UDLQFXUUHQW&K&203&K9FF
Figure 29. Output short-circuit at 265 Vac (zoom view 2)
&K'UDLQVRXUFHYROWDJH&K'UDLQFXUUHQW&K&203&K9FF
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No load
8
AN4214
No load
In Figure 30 and Figure 31, some no load waveforms of the circuit are captured. When the
control voltage on the COMP pin decreases below the Burst mode threshold of the L6564
(2.4 V typ.), IC gate driver output is inhibited and its consumption reduced.
Figure 30. No load waveforms at 140 Vac
&K'UDLQVRXUFHYROWDJH&K'UDLQFXUUHQW&K9FF&K&203
Figure 31. No load waveforms at 265 Vac
&K'UDLQVRXUFHYROWDJH&K'UDLQFXUUHQW&K9FF&K&203
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9
Harmonics measurements
Harmonics measurements
At different mains voltage levels, the harmonic contents in mains current and its total
harmonic distortion (THD) are noted to compare with the IEC61000-3-2 mainly for Class-C
equipment.
Figure 32. Current THD at 150 Vac mains
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Harmonics measurements
AN4214
Figure 33. Current THD at 190 Vac mains
Figure 34. Current THD at 230 Vac mains
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Harmonics measurements
Figure 35. Current THD at 265 Vac mains
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;
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Schematic of SMPS
AN4214
Schematic of SMPS
Figure 36. Schematic of SMPS
AN4214
11
Bill of material
Bill of material
Table 5. Bill of material
Sr. no.
Part
reference
Part description
Qty.
Package
1
R2, R8, R7,
R11, R14
Resistor 1 M
5
SMD 1206
2
R4, R8
Resistor 220 K
2
SMD 1206
3
R3
Resistor CFR, 47 /0.5 W
1
TH
4
R5
Resistor 100 K/2 W
1
TH, axial
5
R13
Resistor 47 
1
SMD 0805
6
R21
Resistor 1 M
1
SMD 0805
7
R31
Resistor 240 
1
SMD 0805
8
R25, R17
Resistor 0 
2
SMD 0805
9
R28
Resistor 100 
1
SMD 0805
10
R22
Resistor 19 K
1
SMD 0805
11
R16
Resistor 47 K
1
SMD 0805
12
R29
Resistor 10 K
1
SMD 0805
13
R33, R34
Resistor 0.47 
2
SMD 1206/TH
14
R18
Resistor 15 K, 1%
1
SMD 0805
15
R12
Resistor 68 K
1
SMD 0805
16
R26
Resistor 2.2 K
1
SMD 0805
17
R19
Resistor 5.6 K
1
SMD 0805
18
R9, R10
Resistor 0.14 , 1%
2
SMD 1206
19
R24
Resistor 1 K
1
SMD 0805
20
R27
Resistor 22 K
1
SMD 0805
21
R30
Resistor 15 
1
SMD 0805
22
R36
Resistor 18 K
1
SMD 0805
23
R32
Resistor 120 K, 1%
1
SMD 0805
24
R35
Resistor 8.2 K, 1%
1
SMD 0805
25
R37
Resistor 4.3 K, 1%
1
SMD 0805
26
R1
Resistor, DNL
1
SMD 0805
27
R15
Resistor, DNL
1
SMD 0805
28
R23
Resistor, DNL
1
SMD 0805
29
C6
Capacitor X2 type, 220 nF/275 Vac
1
TH
30
C3
Capacitor X2 type, 100 nF/275 Vac
1
TH
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Bill of material
AN4214
Table 5. Bill of material (continued)
Sr. no.
Part
reference
Part description
Qty.
Package
31
C2,C10, C23,
C26
Capacitor Y2 type, 2.2 nF/250 Vac
4
TH
32
C4
Capacitor polyester type 220 nF/630 Vdc
1
TH
33
C13, C17,
C21
Capacitor ceramic 2.2nF/50V
3
SMD 0805
34
C18
Capacitor ceramic 1 F/25 V
1
SMD 0805
35
C22
Capacitor ceramic 22 pF/50 V
1
SMD 0805
36
C14,C19,
C20, C15
Capacitor ceramic 100 nF/50 V
4
SMD 0805
37
C5
Capacitor film type 1 nF/400 Vdc
or 1 KV disc
1
TH
38
C1
Capacitor film type - DNL
1
TH
39
C11
Capacitor ceramic 100 nF/100 V
1
SMD 1206
40
C24
Capacitor ceramic 1 nF/50 V
1
SMD 0805
41
C25
Capacitor ceramic 470 nF/25 V
1
SMD 0805
42
C16
Capacitor electrolytic 47 F/50 V
1
TH
43
C7, C8
Capacitor electrolytic 220 F/100 V
2
TH
44
C12
Capacitor electrolytic 10 F/35 V
1
TH
45
F1
Fuse 3 A glass
1
Axial
46
L1
Line inductor 470 H
1
TH, drum type dia. = 6 mm
47
L3
Common mode inductor 20 mH,
EF20 type
1
TH, 8 pins horizontal
48
L2
DC filter inductor, 10 H/3 Amp
1
TH, drum type dia. = 6 mm
49
T1
Transformer ER28/17/11
1
TH, 12 pins
horizontal
50
D2, D3, D4,
D5
Diode 1N5408
4
CASE 267-05,
axial lead
ON Semiconductor
51
D9
Diode 1N4148
1
SOD27; DO-35
NXP
Semiconductors
52
D8
Diode BAV21
1
SOD27; DO-35
NXP
Semiconductors
53
D6
Diode STTH1L06A
1
SMD - SMA
package
STMicroelectronics
54
DZ2
Zener diode 18 V/0.5 W
1
TH
55
DZ2
Zener diode 12 V/0.5 W
1
TH
56
D1
Fast rectifier STTH3R04S
1
SMD - SMC
package
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STMicroelectronics
AN4214
Bill of material
Table 5. Bill of material (continued)
Sr. no.
Part
reference
Part description
Qty.
Package
Manufacturer
57
D7
Fast rectifier STPS1150
1
SMD - SMA
package
STMicroelectronics
58
U1
PFC controller, L6564D
1
SMD - SSO-10
package
STMicroelectronics
59
U2
Optocoupler PC817A
1
SMD - SO-4
60
U3
SEA05
1
SMD- SOT23-6L
STMicroelectronics
61
M1
MOSFET STP7N80K5
1
TO-220
STMicroelectronics
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CVCC controller
12
AN4214
CVCC controller
The SEA05 is ST’s advanced constant voltage, constant current driver designed for
secondary side control for SMPS, battery charging and LED driving applications. One can
implement the secondary side CVCC control using the SEA05 to achieve good stability in
terms of temperature variations and better efficiency.
The SEA05 is a highly integrated solution for SMPS applications requiring a dual control
loop to perform CV (constant voltage) and CC (constant current) regulation. The device
integrates a voltage reference, two op-amps (with OR-ed open-drain outputs), and a low
side current sensing circuit. The voltage reference, along with one op-amp, is the core of the
voltage control loop; the current sensing circuit and the other op-amp make up the current
control loop. The external components needed to complete the two control loops are:
a resistor divider that senses the output of the power supply and fixes the voltage regulation
set-point at the specified value; a sense resistor that feeds the current sensing circuit with
a voltage proportional to the DC output current (this resistor determines the current
regulation set-point and must be adequately rated in terms of power dissipation), and the
frequency compensation components (R-C networks) for both loops. The device, housed in
one of the smallest available packages, is ideal for space-limited applications such as
adapters and chargers. Some of the features of this device are as follows:

Constant voltage and constant current control

Wide operating VCC range: 3.5 - 36 V

Low quiescent consumption: 200 µA

Voltage reference: 2.5 V

Voltage control loop accuracy: ± 0.5%

Current sense threshold: 50 mV

Open-drain output stage

Low external component count

SOT23-6L micro package
The pin diagram, typical application schematic and package are show in figures 37 and 38.
Figure 37. SEA05 internal circuit and its application in flyback topology
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CVCC controller
Figure 38. SEA05 package and pinout
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References
13
14
AN4214
References

AN1059: Design equations of high-power-factor flyback converters based on the
L6561

AN2838: 35 W wide-range high power factor flyback converter evaluation board using
the L6562A

L6564 datasheet

SEA05 datasheet
Revision history
Table 6. Document revision history
Date
Revision
02-Dec-2014
1
Initial release.
2
Updated Section 2: SMPS description on page 6 (updated device
and package name).
Updated Table 1: Basic specifications of SMPS on page 10 (updated
parameters and limits, added note 1.).
Updated Figure 36: Schematic of SMPS on page 30 (replaced by
new figure).
Updated Table 5: Bill of material on page 31 (replaced by new table).
Minor modifications throughout document.
12-Jan-2015
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Changes
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