36W evaluation board using ICE2QS03G

Application Note, V1.2, 12 November 2011
N e v e r
s t o p
t h i n k i n g .
Published by
Infineon Technologies AG
81726 Munich, Germany
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Title
Revision History:
12 November 2011
Previous Version:
V1.1
Page
Subjects (major changes since last revision)
12, 13
Revise typo in auxiliary winding turns
36W Evaluation Board with Quasi-Resonant PWM Controller ICE2QS03G
License to Infineon Technologies Asia Pacific Pte Ltd
Eric Kok
[email protected]
Wang Zan
[email protected]
He Yi
[email protected]
Jeoh Meng Kiat
[email protected]
We Listen to Your Comments
Any information within this document that you feel is wrong, unclear or missing at all?
Your feedback will help us to continuously improve the quality of this document.
Please send your proposal (including a reference to this document) to:
[email protected]
V1.2
AN-PS0040
EVALQRS-36W-ICE2QS03G
Table of Contents
1
Content................................................................................................................ 5
2
Evaluation Board................................................................................................ 5
3
List of Features .................................................................................................. 5
4
Technical Specifications ................................................................................... 5
5
Circuit Description ............................................................................................. 6
5.1
Mains Input and Rectification .....................................................................................................6
5.2
PWM Control ................................................................................................................................6
5.3
Snubber Network .........................................................................................................................6
5.4
Output Stage ................................................................................................................................6
5.5
Feedback Loop.............................................................................................................................6
6
Circuit Operation................................................................................................ 6
6.1
Startup Operation ........................................................................................................................6
6.2
Normal Mode Operation ..............................................................................................................7
6.3
Digital Frequency Reduction ......................................................................................................7
7
Protection Features ........................................................................................... 7
7.1
Vcc under voltage protection .....................................................................................................7
7.2
Foldback point protection...........................................................................................................7
7.3
Open loop/over load protection..................................................................................................7
7.4
Adjustable output overvoltage protection.................................................................................7
7.5
Short winding protection ............................................................................................................7
8
Circuit diagram................................................................................................... 8
8.1
PCB Topover layer.......................................................................................................................9
8.2
PCB Bottom Layer .....................................................................................................................10
9
Component List................................................................................................ 11
10
Transformer Construction............................................................................... 12
11
Test Results...................................................................................................... 13
11.1
Efficiency ....................................................................................................................................13
12
References........................................................................................................ 15
Application Note
4
12 November 2011
EVALQRS-36W-ICE2QS03G
1
Content
The demo-board described here is a 36W power supply using quasi-resonant flyback converter topology.
The PWM controller ICE2QS03G is a second generation quasi-resonant controller IC developed by Infineon
Technologies. The typical applications are for TV-sets, DVD-players, Set-top boxes, netbook adapters, home
audio and printer applications. In normal operation, the digital frequency reduction with decreasing load
enables a quasi-resonant operation till very low load. As a result, the system efficiency over the entire load
range is significantly improved compared to conventional free running quasi resonant converter implemented
with only maximum switching frequency limitation. In addition, numerous protection functions have been
implemented in ICE2QS03G to protect the system and customize the IC for the chosen application. In case
of failure modes, like open control-loop/over load, output overvoltage, and transformer short winding, the
device switches into Auto Restart Mode or Latch-off Mode. By means of the cycle-by-cycle peak current
limitation plus foldback point correction, the dimension of the transformer and the secondary diode can be
lower which leads to more cost effective design.
2
Evaluation Board
Figure 1-EVALQRS-36W-ICE2QS03G
3
List of Features
Quasi-resonant operation
Digital frequency reduction with decreasing load
Cycle-by-cycle peak current limitation with foldback point correction
Built-in digital soft-start
Direct current sensing with internal Leading Edge Blanking Time
VCC undervoltage protection: IC stop operation, recover with softstart
VCC overvoltage protection: IC stop operation, recover with softstart
Openloop/Overload protection: Auto Restart after fixed blanking time
Output overvoltage protection: Latch-off with adjustable threshold
Short-winding protection: Latch-off
4
Technical Specifications
Application Note
5
12 November 2011
EVALQRS-36W-ICE2QS03G
Input voltage
Input frequency
Output voltage and current
Output power
Efficiency
Minimum switching frequency at full load,
minimum input voltage
5
85VAC~265VAC
50Hz, 60Hz
12V 3A
36W
>88% at full load
38kHz
Circuit Description
5.1
Mains Input and Rectification
The AC line input side comprises the input fuse F1 as overcurrent protection. The X2 Capacitors C1,and
Choke L1 forms a main filter to minimize the feedback of RFI into the main supply. After the bridge rectifier
BR1, together with a smoothing capacitor C3, provide a voltage of 80VDC to 380 VDC depending on mains
input voltage.
5.2
PWM Control
The PWM pulse is generated by the 8-pin Quasi Resonant PWM curremt-mode Controller ICE2QS03G. It
comprises the complete control for quasi-resonant flyback switch mode power supply especially in netbook
adapter, home audio and printer applications. The PWM switch-on is determined by the zero-crossing input
signal and the value of the up/down counter. The PWM switch-off is determined by the feedback signal VFB and
the current sensing signal VCS. ICE2QS03G also performs all necessary protection functions in flyback
converters. Details about the information mentioned above are illustrated in the product datasheet.
5.3
Snubber Network
A snubber network D1 and D5 dissipate the energy of the leakage inductance and to suppress ringing on the
SMPS transformer. The Transient voltage suppression diode D5 absorbs the voltage spike larger than 207V.
5.4
Output Stage
On the secondary side, 12V output, the power is coupled out via a dual schottky diode D2. The capacitors
C12 and C13 provide energy buffering followed by the L-C filters to reduce the output ripple and prevent
interference between SMPS switching frequency and line frequency considerably. Storage capacitors C12,
C13 are designed to have an internal resistance as small as possible (ESR). This is to minimize the output
voltage ripple caused by the triangular current.
5.5
Feedback Loop
For feedback, the output is sensed by the voltage divider of R16, R17 and R18 and compared to TL431
internal reference voltage. C15, C16 and R19 comprise the compensation network. The output voltage of
TL431 is converted to the current signal via Optocoupler and two resistors R20 and R21 are for regulation
control.
6
Circuit Operation
6.1
Startup Operation
When VCC reaches the turn on voltage threshold 18V, the IC begins with a soft start which is realized
internally with a built-in digital block. The maximum soft start time is 12ms. During this period, feedback
voltage will be generated internally, which is 1.76V at the first step and increases step by step with preset
voltage at a time interval of 4ms. In such a way, the primary peak current and the gate drive pulse width are
both gradually increased during the soft start.
Application Note
6
12 November 2011
EVALQRS-36W-ICE2QS03G
6.2
Normal Mode Operation
The secondary output voltage is built up after startup. The secondary regulation control is adopted with
TL431 and optocoupler. The compensation network C15, C16 and R19 constitutes the external circuitry of
the error amplifier of TL431. This circuitry allows the ouput voltage to be precisely controlled to dynamically
varying load conditions, therefore providing stable control.
6.3
Digital Frequency Reduction
During normal operation, the switching frequency for ICE2QS03G is digitally reduced with decreasing load.
At light load, the MOSFET will be turned on not at the first minimum drain-source voltage time, but on the n th.
The counter is in range of 1 to 7, which depends on feedback voltage in a time-base. The feedback voltage
decreases when the output power requirement decreases, and vice versa. Therefore, the counter is set by
monitoring voltage VFB. The counter will be increased with low VFB and decreased with high VFB. The
thresholds are preset inside the IC.
7
Protection Features
7.1
Vcc under voltage protection
During normal operation, the VCC voltage is continuously monitored. When the Vcc voltage falls below the
under voltage lock out level (VCCoff), the IC is off and gate signal is disabled.
7.2
Foldback point protection
For a quasi-resonant flyback converter, the maximum possible output power will increas when a constant current
limit value is used for all the mains input voltage range. This is usually not desired as it will increase additional
cost on transformer and output diode incase of output over power conditions.
The internal fold back protection is implemented to adjust the VCS voltage limit according to the bus voltage. Here,
the input line voltage is sensed using the current flowing out of ZC pin, during the MOSFET on-time. As the result,
the maximum current limit will be lower at high input voltage and the maximum output power can be well limited
versus the input voltage. Resistor R2 determines the foldback point by setting the current flowing out the ZC pin.
7.3
Open loop/over load protection
In case of open control loop, feedback voltage is pulled up with internally block. After a fixed blanking time,
the IC enters Auto restart mode. In case of secondary short-circuit or overload, regulation voltage VFB will
also be pulled up, same protection will be applied and IC will enters Auto restart mode.
7.4
Adjustable output overvoltage protection
During off-time of the power switch, the voltage at the zero-crossing pin ZC is monitored for output
overvoltage detection. If the voltage is higher than the preset threshold 3.7V for a preset period, the IC is
latched off. R4 and R2 constitute the voltage divide network.R2 is determined by the foldback point
correction voltage. After R2 is determined, R4 can be determined by the over voltage protection point
according to the threshold of Vzc OVP voltage.
7.5
Short winding protection
The source current of the MOSFET is sensed via shunt resistors R10. If the voltage at the current sensing
pin is higher than the preset threshold VCSSW of 1.68V during the on-time of the power switch, the IC is
latched off. This implements a short winding protection. To avoid an accidental latch off, a spike blanking
time of 190ns is integrated in the output of internal comparator.
Application Note
7
12 November 2011
EVALQRS-36W-ICE2QS03G
8
Circuit diagram
T1
4
3
P6KE150A
25V
1000uF
D1
UF4005
100uF/400V
4
1M
IPP60R600CP
R22
Q1
1
2
C14
12
4
CON2
470uF
25V
1000uF
25V
6
Com
C6
1
275V
Np:Ns:Naux=40:5:8 600uH
3
10k
R10
0.5R/0.5W
R3
0.1uF
33uF/35V
C10
39pF 1
7 Vcc
2R
R16
39k, 1%
5 HV
IC1
4 Gate
4
R20
1.2k
1
3 CS
C16
2
R17
6.8k
3
2 FB
2
8
2.2nF
110
1N4148
1 ZC ICE2QS03G
8 Gnd
C5
D3
2
C11
R4
8.2k
47K
R2
1nF
4
1
3
2
IC2
36W(12V X 3A) SMPS Demo Board using ICE2QS03G and IPP06N600CP(V 1.0)
SFH617A-3
100pF
R21
680R
R19
22k
1
C8
5
C9
2
7
1
3
C15
100nF
3
IC3
TL431
2
22VZD1
R18
12k, 1%
Figure 2 – Schematics
Application Note
J2
2
+
C13
1
R13
C12
47pF/1kV
2
1
12V/3A
L2
1.5uH
D2
VF30100SG
2
N
C1
7
C3
BR1
- 800V
2A
~
1
2
9
D5
3
CON1
1
1
85V ~ 265 V
2A
J1
1M
R12
2*27mH0.9A
L1
2
~
F1
L
1
2
305V
0.47uF
8
12 November 2011
EVALQRS-36W-ICE2QS03G
8.1
PCB Topover layer
Figure 3 – Component side Component Legend – View from Topside
Application Note
9
12 November 2011
EVALQRS-36W-ICE2QS03G
8.2
PCB Bottom Layer
Figure 4 Solder side copper – View from Topside
Application Note
10
12 November 2011
EVALQRS-36W-ICE2QS03G
9
Component List
Items
Circuit code
1
BR1
2
Description
Part No.
Manufacturer
Bridge rectifier, 2A 800V
2KBB80R
C1
X-cap, 0.47uF 305V
B32922C3474K
3
C10
39pF, 50V NPO SMD 0805
39pF, 50V, NPO, SMD 0805
4
C11
1nF, 50V NPO SMD 0805
1nF, 50V NPO SMD 0805
5
C12
1000uF/25V KZE 12.5x20
1000uF/25V KZE 12.5x20
6
C13
1000uF/25V KZE 12.5x20
1000uF/25V KZE 12.5x20
7
C14
470uF/25V KZE 8x20
470uF/25V KZE 8x20
8
C15
100nF 50V X7R 0805
100nF 50V X7R 0805
9
C16
100pF 50V NPO 0805
100pF 50V NPO 0805
10
C3
100uF/400V18x26
100uF/400V18x26
11
C5
Y2 cap. 2.2nF/250V
Y2 cap. 2.2nF/250V
12
C6
47pF/1kV SL
DEA1X3A470JC1B
Murata
13
C8
33uF/35V 5x11
B41851A7336M000
Epcos
14
C9
0.1uF 50V X7R, 1206
0.1uF 50V X7R, 1206
15
D1
Ultra-fast diode UF4005
UF4005
Vishay
16
D2
Schottky diode 30A 100V
VF30100SG
Vishay
17
D3
Mini MELF diode LL4148
LL4148
18
D5
TVS 150V 600W
P6KE150A
19
F1
372-2A
20
IC1
ICE2QS03G
Infineon
21
IC2
Fuse 2A 250V TR5/372
Quasi-Resonant controller
ICE2QS03G (SO-8)
Opto-coupler SFH617A-3
SFH617A-3
Vishay
22
IC3
Error Amp regulator TL431 SOT89
TL431 SOT89
23
L1
Input CMC 2*27mH 0.9A
B82732F2901B001
Epcos
24
L2
O/P filter 1.5μH 6.3A
13R152C
Epcos
25
Q1
CoolMOS 60A 600V IPP60R600CP
IPP60R600CP
26
R10
0.5Ω / 0.5W (SMD 2010)
WSL2010R5000FEA
27
R12
1MΩ SMD 1206
1MΩ SMD 1206
28
R13
1MΩ SMD 1206
1MΩ SMD 1206
29
R16
39kΩ, 1% SMD 0805
39kΩ, 1% SMD 0805
30
R17
6.8kΩ 1% SMD 0805
6.8kΩ 1% SMD 0805
31
R18
12kΩ, 1% SMD 0805
12kΩ, 1% SMD 0805
32
R19
22kΩ SMD 0805
22kΩ SMD 0805
33
R2
47KΩ SMD 0805
47KΩ SMD 0805
34
R20
1.2kΩ SMD 0805
1.2kΩ SMD 0805
35
R21
680Ω SMD 0805
680Ω SMD 0805
36
R22
10kΩ SMD 0805
10kΩ SMD 0805
37
R3
0Ω SMD 0805
0Ω SMD 0805
38
R4
8.2kΩ SMD 0805
8.2kΩ SMD 0805
Application Note
11
Epcos
Vishay
Infineon
Vishay
12 November 2011
EVALQRS-36W-ICE2QS03G
39
T1
40
ZD1
Lp=0.6mH (N87 RM10)
core : B65814N1012D1
22V zener diode mini MELF
BZV55B22/TZM525113/ZLL5225
EPCOS
Table 1– Component List
10
Transformer Construction
Core and material: RM10, N87
Bobbin: 8 pin Version (vertical bobbin)
Primary Inductance, Lp=600μH, measured between pin 1 and pin 12 (Gapped to Inductance)
Pin 10
8 turns 1 x AWG#29 (Aux.)
Pin 3
Pin 12 : not solder to the pin
but 38mm length with tubing
10 turns 2 x AWG#28 (Prim.)
Pin 12
Pin 7
5 turns 2 x TRIPLE Ø0.45 (Sec.)
Pin 6
b
Pin 9
Pin 4
Pin 1
Pin 1 : not solder to the pin but
20mm length with tubing
c
10 turns 2 x AWG#28 (Prim.)
10 turns 2 x AWG#28 (Prim.)
5 turns 2 x TRIPLE Ø0.45 (Sec.)
a
10 turns 2 x AWG#28 (Prim.)
Figure 5 – Transformer structure
Botom view
Top view
Figure 6 – Transformer complete – bottom and top view
Application Note
12
12 November 2011
EVALQRS-36W-ICE2QS03G
Start
3
Stop
10
No. of turns
8
Wire size
1XAWG#29
Layer
Auxiliary
c
12
10
2XAWG#28
1/4 Primary
6
7
5
2Xtriple wireΦ 0.65
Secondary
b
c
(not broken)
10
2XAWG#28
1/4 Primary
a
b
(not broken)
10
2XAWG#28
1/4 Primary
4
9
5
2Xtriple wireΦ 0.65
Secondary
1
a
(not broken)
10
2XAWG#28
1/4 Primary
Table 2 Wire size requirement
11
Test Results
11.1
Efficiency
Table 3 – Efficiency vs. Load
Vin(AC)
115
230
Application Note
Load
Pin(W)
Vout(V)
Iout(A)
Pout(W)
Efficiency
100% load
40.9896
12.003
3.0015
36.027
87.9%
75% load
30.468
12.005
2.2493
27.00285
88.6%
50% load
20.2398
12.007
1.499
17.99849
88.9%
25% load
10.0968
12.009
0.7506
9.013955
89.3%
100% load
40.1994
12.003
3.0012
36.0234
89.6%
75% load
30.1722
12.005
2.249
26.99925
89.5%
50% load
20.1534
12.007
1.499
17.99849
89.3%
25% load
10.284
12.009
0.7509
9.017558
87.7%
13
12 November 2011
EVALQRS-36W-ICE2QS03G
Efficiency Vs Load
90.0%
89.6%
89.5%
89.5%
89.3%
89.3%
88.9%
89.0%
Efficiency
88.6%
88.5%
87.9%
88.0%
87.5%
87.7%
230Vac
87.0%
115Vac
86.5%
25%
50%
75%
100%
Load
Figure 7 – Active Load Efficiency
1)
No load input power Vs line voltage
45
40.446
40
35
30.858
30
31.994
32.898
34.044
29.058
25
20
90
115
150
180
230
265
Input Line Voltage(Vac)
Figure 8 No Load Input Power Vs Line Voltage
1) input discharge resistor R12 and R13 not included
Application Note
14
12 November 2011
EVALQRS-36W-ICE2QS03G
12
References
[1]
ICE2QS03G datasheet, Infineon Technologies AG, 2009
[2]
ICE2QS03G design guide, Infineon Technologies, 2010. [ANPS0045]
[3]
Design tips for flyback converters using the Quasi-Resonant PWM controller ICE2QS01, Infineon
Technologies, 2006. [ANPS0005]
[4]
Converter design using the quasi-resonant PWM controller ICE2QS01, application notes, Infineon
Technologies, 2006. [ANPS0003]
[5]
Determine the switching frequency of Quasi-Resonant flyback converters designed with ICE2QS01,
Infineon Technologies, 2006. [ANPS0004]
[6]
ICE2QRxx65/80x design guide, Infineon Technologies, 2011. [ANPS0053]
[7]
CoolMOS IPP60R600CP datasheet Rev 2, Infineon Technologies AG, 2008
Application Note
®
15
12 November 2011
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