DER-228 - Feryster

Design Example Report
Title
15 W Power Supply with <30 mW No-load
Input Power Using TinySwitch-III (TNY278P)
Specification 85 VAC – 265 VAC Input; 12 V, 1.25 A Output
Application
TinySwitch-III Reference Design
Author
Applications Engineering Department
Document
Number
DER-228
Date
July 23, 2009
Revision
1.0
Summary and Features
•
•
•
•
•
EcoSmart® – Meets all existing and proposed harmonized energy efficiency standards
including: CECP (China), CEC, EPA, AGO, European Commission
• No-load consumption < 30 mW at 230 VAC
• > 81% active-mode efficiency
• Exceeds ENERGY STAR v2 / EuP tier 2 requirements of 79%
BP/M capacitor value selects MOSFET current limit for greater design flexibility
Tightly toleranced I2f parameter (–10%, +12%) reduces system cost:
• Increases MOSFET and magnetics power delivery
• Reduces overload power, which lowers output diode and capacitor costs
Integrated TinySwitch-III Safety/Reliability features:
• Accurate (± 5%), auto-recovering, hysteretic thermal shutdown function maintains safe PCB
temperatures under all conditions
• Auto-restart protects against output short circuit and open loop fault conditions
• > 3.2 mm creepage on package enables reliable operation in high humidity and high
pollution environments
Meets EN550022 and CISPR-22 Class B conducted EMI with >12 dB margin
PATENT INFORMATION
The products and applications illustrated herein (including transformer construction and circuits external to the products) may be covered
by one or more U.S. and foreign patents, or potentially by pending U.S. and foreign patent applications assigned to Power Integrations. A
complete list of Power Integrations' patents may be found at www.powerint.com. Power Integrations grants its customers a license under
certain patent rights as set forth at <http://www.powerint.com/ip.htm>.
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
23-Jul-09
Table of Contents
1
2
3
4
Introduction.................................................................................................................4
Power Supply Specification ........................................................................................6
Circuit Diagram...........................................................................................................7
Circuit Description ......................................................................................................8
4.1
Input Rectification and Filtering ...........................................................................8
4.2
TNY278PN Operation .........................................................................................8
4.3
Bias Winding Design ...........................................................................................9
4.4
Output Rectification and Filtering ........................................................................9
4.5
Feedback and Output Voltage Regulation...........................................................9
4.6
EMI Design Aspects ............................................................................................9
4.7
Peak Primary Current Limit Selection..................................................................9
5 PCB Layout ..............................................................................................................11
6 Bill of Materials .........................................................................................................12
7 Transformer Specification.........................................................................................13
7.1
Electrical Diagram .............................................................................................13
7.2
Electrical Specifications.....................................................................................13
7.3
Materials............................................................................................................14
7.4
Transformer Build Diagram ...............................................................................14
7.5
Transformer Construction..................................................................................15
8 Transformer Design Spreadsheet.............................................................................16
9 Performance Data ....................................................................................................18
9.1
Active Mode Efficiency ......................................................................................18
9.2
Energy Efficiency Requirements .......................................................................19
9.2.1
USA Energy Independence and Security Act 2007 ....................................20
9.2.2
ENERGY STAR EPS Version 2.0 ..............................................................20
9.3
No-load Input Power..........................................................................................21
9.4
Available Output Power vs Input Power (230 VAC)...........................................22
9.5
Available Standby Output Power.......................................................................23
9.6
Regulation .........................................................................................................24
9.6.1
Load and Line ............................................................................................24
10
Thermal Performance ...........................................................................................25
11
Waveforms............................................................................................................26
11.1 Drain Voltage and Current, Normal Operation...................................................26
11.2 Output Voltage Start-Up Profile .........................................................................27
11.3 Drain Voltage and Current Start-Up Profile .......................................................27
11.4 Load Transient Response (75% to 100% Load Step) .......................................28
11.5 Output Ripple Measurements............................................................................29
11.5.1 Ripple Measurement Technique ................................................................29
11.5.2 Measurement Results ................................................................................30
12
Conducted EMI .....................................................................................................31
12.1 115 VAC, Full Load ...........................................................................................31
12.2 230 VAC, Full Load ...........................................................................................32
13
Revision History ....................................................................................................33
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
Important Note:
Although this board was designed to satisfy safety isolation requirements, it has not been
agency approved. Therefore, all testing should be performed using an isolation
transformer to provide the AC input to the power supply.
Page 3 of 34
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
23-Jul-09
1 Introduction
This report describes a universal input, 12 V, 1.25 A flyback power supply using a
TNY278P device from the TinySwitch-III family of ICs. The goal of the design was to
demonstrate the very low no-load input power that is achievable with TinySwitch-III
devices
AC
AC
+
-
+
Figure 1 – DER-228 Populated Circuit Board Photographs (3.2 × 1.8 inches).
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
The design was based on the EP91 reference design board with the only changes being
optimization of the bias winding components that supply the operating current into the
BYPASS pin of the TNY278P IC and changing the output diode from a PN ultra fast to
Schottky barrier type.
The report contains the complete specification of the power supply, a detailed circuit
diagram, the entire bill of materials required to build the supply, extensive documentation
of the power transformer, along with test data and oscillographs of the most important
electrical waveforms. The board provides a number of user configurable options which
are designed to demonstrate the features and flexibility of the TinySwitch-III family. These
include easy adjustment of the device current limit for increased output power or higher
efficiency operation, and a latched output overvoltage shutdown.
Page 5 of 34
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
23-Jul-09
2 Power Supply Specification
The table below represents the minimum acceptable performance of the design. Actual
performance is listed in the results section.
Description
Input
Voltage
Frequency
No-load Input Power (230 VAC)
Output
Output Voltage
Output Ripple Voltage
Output Current
Total Output Power
Continuous Output Power
Efficiency
Full Load
Required average efficiency at
25, 50, 75 and 100 % of POUT
Symbol
Min
VIN
fLINE
85
47
11
Typ
Max
Units
Comment
VAC
Hz
W
2 Wire – no P.E.
50/60
265
64
0.03
13
100
12
w/o UVLO resistor or bias winding
VOUT
VRIPPLE
IOUT
1.25
V
mV
A
POUT
15
W
η
81
%
Measured at POUT 25 C
ηES2
ηEuP
79
%
Per Energy Star 2.0 standard
± 8%
20 MHz bandwidth
o
Environmental
Conducted EMI
Meets CISPR22B / EN55022B
Safety
Designed to meet IEC950,
UL1950 Class II
Board size
3.2 x 1.8
81.3 x 45.7
Ambient Temperature
TAMB
0
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40
Inches
mm
o
C
Length x width
Free convection, sea level
Page 6 of 34
23-Jul-09
DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
3 Circuit Diagram
Figure 2 – DER-228 Circuit Diagram.
Page 7 of 34
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
23-Jul-09
4 Circuit Description
This flyback power supply was designed around the TNY278PN (U1 in Figure 2). The
output voltage is sensed and fed back to U1 through optocoupler U2. The feedback
signal is used to maintain constant voltage (CV) regulation of the output via ON/OFF
control.
4.1 Input Rectification and Filtering
Diodes D1–D4 rectify the AC input. Capacitors C1 and C2 filter the rectified DC. Inductor
L1, C1 and C2 form a pi filter that attenuates differential mode conducted EMI.
4.2 TNY278PN Operation
The TNY278PN device (U1) integrates an oscillator, a switch controller, startup and
protection circuitry, and a power MOSFET, all on one monolithic IC.
One side of the power transformer (T1) primary winding is connected to the positive leg
of C2, and the other side is connected to the DRAIN pin of U1. At the start of a switching
cycle, the controller turns the MOSFET on and current ramps up in the primary winding,
which stores energy in the core of the transformer. When that current reaches the current
limit threshold, the controller turns the MOSFET off. Due to the phasing of the
transformer windings and the orientation of the output diode, the stored energy then
induces a voltage across the secondary winding, which forward biases the output diode,
and the stored energy is delivered to the output capacitor.
During MOSFET turns off, the leakage inductance of the transformer induces a voltage
spike on the drain node. The amplitude of that spike is limited by an RCDZ clamp
network that consists of D5, C4, R2, R1 and VR1. Resistor R2 also limits the reverse
current that flows through D5 when the MOSFET turns on. This allows a slow, low-cost,
glass passivated diode (with a recovery time of ≤2 µs.) to be used for D5, which improves
conducted EMI and efficiency. Alternately a fast diode like that FR106 may be used in
place of D5 with a slight reduction in efficiency.
Using ON/OFF control, U1 skips switching cycles to regulate the output voltage, based
on feedback to its EN/UV pin. The EN/UV pin current is sampled, just prior to each
switching cycle, to determine if that switching cycle should be enabled or disabled. If the
EN/UV pin current is <115 µA, the next switching cycle begins, and is terminated when
the current through the MOSFET reaches the internal current limit threshold. To evenly
spread switching cycles, preventing group pulsing, the EN pin threshold current is
modulated between 115 µA and 60 µA based on the state during the previous cycle.
A state-machine within the controller adjusts the MOSFET current limit threshold to one
of four levels, depending on the load being demanded from the supply. As the load on the
supply drops, the current limit threshold is reduced. This ensures that the effective
switching frequency stays above the audible range until the transformer flux density is
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23-Jul-09
DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
low. When the standard production technique of dip varnishing is used for the
transformer, audible noise is practically eliminated.
4.3 Bias Winding Design
Although a bias winding is not necessary for the operation of the TinySwitch-III family, its
use greatly reduces the no load consumption of a power supply. During steady state
operation the bias winding supplies the IC bias current. Resistors R3 and R8 were
adjusted to minimize the no-load input power by providing the supply current required by
U1 at no-load.
4.4 Output Rectification and Filtering
Diode D7 rectifies the output of T1. A schottky barrier type was selected to improve
efficiency. Output voltage ripple was minimized by using a low ESR capacitor for C10
(see Section 6 for component part numbers and values). A post filter (ferrite bead L2 and
C11) attenuates the high frequency switching noise.
4.5 Feedback and Output Voltage Regulation
The supply’s output voltage regulation set-point is set by the voltage that develops across
Zener diode VR3, R6 and the LED in opto-coupler U2. Resistor R6 limits the maximum
current through U2 during load transients. The value of resistor R6 can be varied slightly
to fine-tune the output regulation set point. When the output voltage rises above the set
point, the LED in U2 becomes forward biased. On the primary side, the photo-transistor
of U2 turns on and draws current out of the EN/UV pin of U1. Just before the start of each
switching cycle, the controller checks the EN/UV pin current. If the current flowing out of
the EN/UV pin is greater than 115 µA, that switching cycle will be disabled. As switching
cycles are enabled and disabled, the output voltage is kept very close to the regulation
set point. For greater output voltage regulation accuracy, a reference IC such as a TL431
can be used in place of Zener diode VR3.
4.6 EMI Design Aspects
An input pi filter (C1, L1 and C2) attenuates conducted, differential mode EMI noise.
Shielding techniques (E-Shield™) were used in the construction of T1 to reduce common
mode EMI displacement currents. When combined with the IC’s frequency jitter function,
these techniques produce excellent conducted EMI performance.
4.7 Peak Primary Current Limit Selection
The value of the capacitor installed on the BP/M pin allows the current limit of U1 to be
selected. The power supply designer can change the current limit of the MOSFET by
simply changing the capacitance value connected to the BP/M pin (see the TinySwitch-III
data sheet for more details).
ƒ
Installing a 0.1 µF capacitor on the BP/M pin selects the standard current
limit of the IC, and is the normal choice for enclosed adapter applications.
Page 9 of 34
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
23-Jul-09
ƒ
Installing a 1 µF capacitor on the BP/M pin reduces the MOSFET current
limit, which lowers conduction losses and improves efficiency (at the
expense of reducing the maximum power capability of the IC).
ƒ
A 10 µF capacitor on the BP/M pin will raise the MOSFET current limit and
extend the power capability of the IC (for higher power applications that do
not have the thermal constraints of an enclosed adapter, or to supply
short-duration, peak load demands).
The DER-228 board comes with a 0.1 µF capacitor installed as C7, which causes U1 to
select the standard current limit specified in the TinySwitch-III data sheet. If C7 were
replaced by a 1 µF capacitor (C8 in the BOM, section 6), the current limit of U1 would be
the same as the standard current limit for a TNY277 device. If a 10 µF capacitor is
installed, the current limit of U1 will be the same as the standard current limit for a
TNY279 device. The flexibility of this option enables the designer to do three things.
First, it allows the designer to measure the effect of switching to an adjacent device
without actually removing and replacing the IC. Second, it allows a larger device to be
used with a lower current limit, for higher efficiency. Third, it allows a smaller device to be
used with a higher current limit in a design when higher power is not required on a
continual basis, which effectively lowers the cost of the supply.
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
5 PCB Layout
Figure 3 – Printed Circuit Board Layout (3.2 × 1.8 inches).
Page 11 of 34
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
23-Jul-09
6 Bill of Materials
Item
1
Qty
1
Ref
Des
C1
2
1
C2
3
4
1
1
C4
C5
22 µF, 400 V, Electrolytic, Low ESR, 901 mΩ, (16
x 20)
OBSOLETE not RoHS compliant see 20-0063400 10 nF, 1 kV, Disc Ceramic
2.2 nF, Ceramic, Y1
5
1
C6
33 µF, 35 V, Electrolytic, Very Low ESR, 300 mΩ,
(5 x 11)
6
1
C7
7
1
C10
8
1
9
4
C11
D1
D2
D3
D4
Description
22 µF, 400 V, Electrolytic, High Ripple, (12.5 x 25)
Mfg
Panasonic
Mfg Part Number
EEU-EB2G220
Nippon Chemi-Con
EKMX401ELL220ML20S
Vishay
Vishay
5HKMS10
440LD22-R
Nippon Chemi-Con
EKZE350ELL330ME11D
100 nF, 50 V, Ceramic, X7R
1000 µF, 25 V, Electrolytic, Very Low ESR, 21
mΩ, (12.5 x 20)
100 µF, 25 V, Electrolytic, Very Low ESR, 130
mΩ, (6.3 x 11)
Epcos
B37987F5104K000
Nippon Chemi-Con
EKZE250ELL102MK20S
Nippon Chemi-Con
EKZE250ELL101MF11D
1000 V, 1 A, Rectifier, DO-41
Vishay
1N4007
Vishay
1N4007GP
10
1
D5
1000 V, 1 A, Rectifier, Glass Passivated, 2 µs,
DO-41
11
12
1
1
D6
D7
200 V, 1 A, Ultrafast Recovery, 50 ns, DO-41
80 V, 3 A, Schottky, DO-201AD
Vishay
Vishay
UF4003-E3
SB380
13
14
15
16
17
18
1
2
1
1
1
1
F1
J1 J4
J2
J3
JP1
L1
Wickman
Keystone
Keystone
Keystone
Alpha
37013150410
5011
5012
5010
298
HTB2-102-281
19
1
L2
3.15 A, 250V,Fast, TR5
Test Point, BLK,THRU-HOLE MOUNT
Test Point, WHT,THRU-HOLE MOUNT
Test Point, RED,THRU-HOLE MOUNT
Wire Jumper, Non insulated, 22 AWG, 0.7 in
1mH, 350m A
3.5 mm x 7.6 mm, 75 Ω at 25 MHz, 22 AWG hole,
Ferrite Bead
Fair-Rite
2743004112
20
21
22
23
24
25
26
1
1
1
1
1
1
1
R1
R2
R3
R6
R7
R8
RV1
1 kΩ, 5%, ¼ W, Carbon Film
100 Ω, 5%, 1/4 W, Carbon Film
47 Ω, 5%, 1/8 W, Carbon Film
390 Ω, 5%, 1/8 W, Carbon Film
1 Ω, 5%, 1/4 W, Carbon Film
8.06 kΩ, 1/4 W, Metal Film
275 V, 45 J, 10 mm, RADIAL
CFR-25JB-1K0
CFR-25JB-100R
CFR-12JB-47R
CFR-12JB-390R
CFR-25JB-1R0
MFR-25FBF-8K06
V275LA10
27
28
29
30
31
1
1
1
1
1
T1
U1
U2
VR1
VR3
Transformer, 10 Pins, Vertical
TinySwitch-III, TNY278PN, DIP-8C
Opto coupler, 80 V, CTR 80-160%, 4-DIP
150 V, 6005 W, 5%, TVS, DO204AC (DO-15)
11 V, 500 mW, 5%, DO-35
Yageo
Yageo
Yageo
Yageo
Yageo
Yageo
Littlefuse
Yih-Hwa
Enterprises
Power Integrations
NEC
Littlelfuse
Vishay
YW-360-02B
TNY278PN
PS2501-1-H-A
P6KE150A
BZX55-C11
* Optional components
Note – All parts are RoHS compliant
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23-Jul-09
DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
7 Transformer Specification
7.1
Electrical Diagram
NC
Cancellation
15T # 30 AWG X2
WDG # 1
Primary
WDG # 2
8
1
Secondary
WDG # 5
7T # 26 T.I.W
30T # 30 AWG
6
3
4
Bias
WDG # 3
6T # 26 AWG X3
5
Figure 4 – Transformer Electrical Diagram.
7.2
Electrical Specifications
Electrical Strength
Primary Inductance
Resonant Frequency
Primary Leakage Inductance
Page 13 of 34
1 second, 60 Hz, from pins 1-5 to pins 6-10
Pins 1-3, all other windings open, measured at
100 kHz, 0.4 V RMS
Pins 1-3, all other windings open
Pins 1-3, with pins 6-8 shorted, measured at
100 kHz, 0.4 V RMS
3000 VAC
1170 µH, ±10%
500 kHz (Min.)
50 µH (Max.)
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
7.3
Materials
Item
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
7.4
23-Jul-09
Description
Core: PC40EE25-Z, TDK or equivalent gapped for AL of 323 nH/T2
Bobbin: EE25, Vertical, 10 pin – Yih-Hwa part # YW-360-02B
Magnet Wire: #30 AWG
Magnet Wire: #26 AWG
Triple Insulated Wire: #26 AWG.
Tape: 3M # 44 Polyester web. 2.0 mm wide
Tape: 3M 1298 Polyester Film, 2.0 mils thick, 8.6 mm wide
Tape: 3M 1298 Polyester Film, 2.0 mils thick, 10.7 mm wide
Tape: 3M 1298 Polyester Film, 2.0 mils thick, 4.0 mm wide
Varnish (applied by dipping only, not vacuum impregnation)
Transformer Build Diagram
6
8
2 mm
1 Layer of Tape
5
Bias Winding
4
1
3
1
2 mm
Primary Winding
Margin
1 Layer of Tape
Tape
Cancellation Winding
No Connect
Figure 5 – Transformer Build Diagram.
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23-Jul-09
7.5
DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
Transformer Construction
Bobbin Set Up
Orientation
Margin Tape
WD1
Cancellation Winding
Insulation
WD#2
Primary winding
Insulation
WD #3
Bias Winding
Insulation
Margin Tape
WD #5
Secondary Winding
Outer Insulation
Core Assembly
Varnish
Page 15 of 34
Set up the bobbin with its pins oriented to the left hand side.
Apply 2.0 mm margin at the pin side of bobbin using item [6]. Match combined
height of shield, primary, and bias windings.
Start at Pin 1. Wind 15 bifilar turns of item [3] from left to right. Wind with tight
tension across entire bobbin evenly. Cut the ends of the bifilar and leave floating.
1 Layer of tape [7] for insulation.
Start at pin 3. Wind 30 turns of item [3] from left to right. Apply 1 Layer of tape [7]
for insulation. Wind another 30 turns from right to left. Wind with tight tension
across entire bobbin evenly. Finish at pin 1.
1 Layer of tape [7] for insulation.
Start at pin 4, wind 6 trifilar turns of item [5]. Wind from left to right with tight
tension. Wind uniformly, in a single layer across entire width of bobbin. Finish on
pin 5.
1 Layer of tape [8] for insulation.
Apply 2.0 mm margin at the pin side of bobbin using item [6]. Match combined
height of secondary windings.
Start at pin 8, wind 7 turns of item [5] from left to right. Wind uniformly, in a single
layer across entire bobbin evenly. Finish on pin 6.
3 Layers of tape [8] for insulation.
Assemble and secure core halves using item [1] and item [9].
Dip varnish using item [10] (do not vacuum impregnate.)
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
23-Jul-09
8 Transformer Design Spreadsheet
ACDC_TinySwitch-III
_032608; Rev.1.26;
Copyright Power
Integrations 2008
INPUT
ENTER APPLICATION VARIABLES
VACMIN
85
VACMAX
265
fL
50
VO
12.00
IO
1.25
Power
n
0.82
Z
0.50
tC
CIN
3.00
44.00
INFO
OUTPUT
Volts
Volts
Hertz
Volts
Amps
15
ENTER TinySwitch-III VARIABLES
TinySwitch-III
TNY278
Chosen Device
Chose Configuration
STD
ILIMITMIN
ILIMITTYP
ILIMITMAX
fSmin
I^2fmin
UNIT
44
Minimum AC Input Voltage
Maximum AC Input Voltage
AC Mains Frequency
Output Voltage (at continuous power)
Power Supply Output Current (corresponding to
peak power)
Watts
Continuous Output Power
Efficiency Estimate at output terminals. Under 0.7 if
no better data available
Z Factor. Ratio of secondary side losses to the total
losses in the power supply. Use 0.5 if no better data
available
mSeconds Bridge Rectifier Conduction Time Estimate
uFarads Input Capacitance
TNY278
User defined TinySwitch-III
TNY278
Standard
Current Limit
0.512
0.550
0.588
124000
35.937
Amps
Amps
Amps
Hertz
A^2kHz
VOR
108.00
108
Volts
VDS
VD
KP
0.55
10
0.55
0.64
Volts
Volts
KP_TRANSIENT
0.37
ENTER BIAS WINDING VARIABLES
VB
11
VDB
NB
VZOV
11.00
0.70
6.14
17.00
Volts
Volts
UVLO VARIABLES
V_UV_TARGET
92.00
Volts
V_UV_ACTUAL
92.20
Volts
RUV_IDEAL
RUV_ACTUAL
3.59
3.60
Mohms
Mohms
92
ACDC_TinySwitch-III_032608_Rev1-26.xls;
TinySwitch-III Continuous/Discontinuous Flyback
Transformer Design Spreadsheet
ENTER TRANSFORMER CORE/CONSTRUCTION VARIABLES
Core Type
EE25
EE25
Core
EE25
Bobbin
EE25_BO
BBIN
AE
0.404
LE
7.34
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Enter "RED" for reduced current limit (sealed
adapters), "STD" for standard current limit or "INC"
for increased current limit (peak or higher power
applications)
Minimum Current Limit
Typical Current Limit
Maximum Current Limit
Minimum Device Switching Frequency
I^2f (product of current limit squared and frequency
is trimmed for tighter tolerance)
Reflected Output Voltage (VOR < 135 V
Recommended)
TinySwitch-III on-state Drain to Source Voltage
Output Winding Diode Forward Voltage Drop
Ripple to Peak Current Ratio (KP < 6)
Transient Ripple to Peak Current Ratio. Ensure
KP_TRANSIENT > 0.25
Volts
Bias Winding Voltage
Bias Winding Diode Forward Voltage Drop
Bias Winding Number of Turns
Over Voltage Protection zener diode voltage.
Target DC under-voltage threshold, above which the
power supply with start
Typical DC start-up voltage based on standard
value of RUV_ACTUAL
Calculated value for UV Lockout resistor
Closest standard value of resistor to RUV_IDEAL
P/N:
Enter Transformer Core
P/N:
EE25_BOBBIN
cm^2
cm
Core Effective Cross Sectional Area
Core Effective Path Length
Page 16 of 34
23-Jul-09
DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
AL
BW
M
1.00
1420
10.2
1
L
NS
2.00
7
2
7
DC INPUT VOLTAGE PARAMETERS
VMIN
VMAX
93
375
CURRENT WAVEFORM SHAPE PARAMETERS
DMAX
0.57
nH/T^2
mm
mm
Volts
Volts
Minimum DC Input Voltage
Maximum DC Input Voltage
Duty Ratio at full load, minimum primary inductance
and minimum input voltage
Average Primary Current
Minimum Peak Primary Current
Primary Ripple Current
Primary RMS Current
IAVG
IP
IR
IRMS
TRANSFORMER PRIMARY DESIGN PARAMETERS
LP
0.22
0.51
0.33
0.31
Amps
Amps
Amps
Amps
1170
uHenries
LP_TOLERANCE
NP
ALG
BM
10
60
323
2828
10.00
BAC
905
ur
LG
BWE
OD
2053
0.12
16.4
0.27
INS
0.05
DIA
AWG
0.22
32
CM
CMA
64
205
Ungapped Core Effective Inductance
Bobbin Physical Winding Width
Safety Margin Width (Half the Primary to Secondary
Creepage Distance)
Number of Primary Layers
Number of Secondary Turns
Typical Primary Inductance. +/- 10% to ensure a
minimum primary inductance of 1064 Uh
%
Primary inductance tolerance
Primary Winding Number of Turns
nH/T^2 Gapped Core Effective Inductance
Gauss
Maximum Operating Flux Density, BM<3000 is
recommended
Gauss
AC Flux Density for Core Loss Curves (0.5 X Peak
to Peak)
Relative Permeability of Ungapped Core
mm
Gap Length (Lg > 0.1 mm)
mm
Effective Bobbin Width
mm
Maximum Primary Wire Diameter including
insulation
mm
Estimated Total Insulation Thickness (= 2 * film
thickness)
mm
Bare conductor diameter
AWG
Primary Wire Gauge (Rounded to next smaller
standard AWG value)
Cmils
Bare conductor effective area in circular mils
Cmils/Amp Primary Winding Current Capacity (200 < CMA <
500)
TRANSFORMER SECONDARY DESIGN PARAMETERS
Lumped parameters
ISP
4.41
Amps
Peak Secondary Current
ISRMS
IRIPPLE
CMS
AWGS
2.35
1.99
470
23
Amps
Amps
Cmils
AWG
Secondary RMS Current
Output Capacitor RMS Ripple Current
Secondary Bare Conductor minimum circular mils
Secondary Wire Gauge (Rounded up to next larger
standard AWG value)
622
Volts
Maximum Drain Voltage Estimate (Assumes 20%
zener clamp tolerance and an additional 10%
temperature tolerance)
VOLTAGE STRESS PARAMETERS
VDRAIN
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
23-Jul-09
9 Performance Data
The ON/OFF control scheme employed by TinySwitch-III yields virtually constant
efficiency across the 25% to 100% load range required for compliance with ENERGY
STAR and EuP energy efficiency standards for external power supplies (EPS). Even at
loads below 10% of the supply’s full rated output power, efficiency remains above 75%,
providing excellent standby performance for applications that require it. This performance
is automatic with ON/OFF control. There are no special burst modes that require the
designer to consider specific thresholds within the load range in order to achieve
compliance with global energy efficiency standards.
All measurements performed at room temperature, 60 Hz input frequency.
9.1
Active Mode Efficiency
85
265 V
230 V
115 V
85 V
Efficiency(%)
83
81
79
77
75
0
0.125
0.25
0.375
0.5
0.625
0.75
0.875
1
1.125
1.25
Output Current (A)
Figure 6 – Efficiency vs. Output Current, Room Temperature, 60 Hz..
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23-Jul-09
DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
Percent of
Full Load
Efficiency (%)
115 VAC
230 VAC
25
82.4
79.2
50
82.7
81.8
75
82.6
82.0
100
82.5
82.4
Average
82.5
81.4
Requirements
US EISA (2007)
74
ENERGY STAR 2.0
79
EuP (tier 2)
79
9.2 Energy Efficiency Requirements
The external power supply requirements below all require meeting active mode efficiency
and no-load input power limits. Minimum active mode efficiency is defined as the
average efficiency of 25, 50, 75 and 100% of output current (based on the nameplate
output current rating).
For adapters that are single input voltage only then the measurement is made at the
rated single nominal input voltage (115 VAC or 230 VAC), for universal input adapters the
measurement is made at both nominal input voltages (115 VAC and 230 VAC).
To meet the standard the measured average efficiency (or efficiencies for universal input
supplies) must be greater than or equal to the efficiency specified by the standard.
The test method can be found here:
http://www.energystar.gov/ia/partners/prod_development/downloads/power_supplies/EP
SupplyEffic_TestMethod_0804.pdf
For the latest up to date information please visit the PI Green Room:
http://www.powerint.com/greenroom/regulations.htm
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
23-Jul-09
9.2.1 USA Energy Independence and Security Act 2007
This legislation mandates all single output single output adapters, including those
provided with products, manufactured on or after July 1st, 2008 must meet minimum
active mode efficiency and no load input power limits.
Active Mode Efficiency Standard Models
Nameplate Output (PO)
Minimum Efficiency in Active Mode of Operation
<1W
≥ 1 W to ≤ 51 W
> 51 W
0.5 × PO
0.09 × ln (PO) + 0.5
0.85
ln = natural logarithm
No-load Energy Consumption
Nameplate Output (PO)
Maximum Power for No-load AC-DC EPS
All
≤ 0.5 W
This requirement supersedes the legislation from individual US States (for example CEC
in California).
9.2.2 ENERGY STAR EPS Version 2.0
This specification takes effect on November 1st, 2008.
Active Mode Efficiency Standard Models
Nameplate Output (PO)
Minimum Efficiency in Active Mode of Operation
≤1W
> 1 W to ≤ 49 W
> 49 W
0.48 × PO + 0.14
0.0626 × ln (PO) + 0.622
0.87
ln = natural logarithm
Active Mode Efficiency Low Voltage Models (VO<6 V and IO ≥ 550 mA)
Nameplate Output (PO)
Minimum Efficiency in Active Mode of Operation
≤1W
> 1 W to ≤ 49 W
> 49 W
0.497 × PO + 0.067
0.075 × ln (PO) + 0.561
0.86
ln = natural logarithm
No-load Energy Consumption (both models)
Nameplate Output (PO)
Maximum Power for No-load AC-DC EPS
0 to < 50 W
≥ 50 W to ≤ 250 W
≤ 0.3 W
≤ 0.5 W
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Page 20 of 34
23-Jul-09
9.3
DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
No-load Input Power
19
No Load Input Power (mW)
18
17
16
15
14
13
12
11
10
80
100
120
140
160
180
200
220
240
260
Input Voltage (VAC)
Figure 7 – No-load Input Power vs. Input Line Voltage, Room Temperature, 60 Hz.
Page 21 of 34
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
Available Output Power vs Input Power (230 VAC)
100000
10000
Input Power (mW)
9.4
23-Jul-09
Po vs Pin
1000
100
10
1
0.1
0.1
1
10
100
1000
10000
100000
Output Power (mW)
Figure 8 – Output Power vs Input Power at 230 VAC, Room Temperature, 60 Hz.
Dashed line represents theoretical ideal (100% efficiency)
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23-Jul-09
DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
9.5 Available Standby Output Power
The chart below shows the available output power versus line voltage at input power
consumption levels of 1, 2 and 3 watts (respectively). Again, this performance illustrates
the value of ON/OFF control, as it automatically maintains a high efficiency, even during
very light loading. This simplifies complying with standby requirements that specify that a
fair amount of power be available to the load at low input power consumption levels. The
TinySwitch-III ON/OFF control scheme maximizes the amount of output power available
to the load in standby operation when the allowable input power is fixed at a low value.
This simplifies the design of products such as printers, set-top boxes, DVD players, etc.
that must meet stringent standby power consumption requirements.
Output Power (W)
3
Pin=3 W
2
Pin=2 W
Pin=1 W
1
0
85
105
125
145
165
185
205
225
245
265
Input Voltage (VAC)
Figure 9 – Available Output Power for 1, 2 and 3 Watts of Input Power.
Page 23 of 34
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
9.6
23-Jul-09
Regulation
9.6.1 Load and Line
13
12.8
265 V
230 V
115 V
Output Voltage (V)
12.6
12.4
85 V
12.2
12
11.8
11.6
11.4
11.2
11
0
0.125 0.25 0.375
0.5
0.625 0.75 0.875
1
1.125 1.25
Output Current (A)
Figure 10 – Load and Line Regulation, Room Temperature.
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23-Jul-09
DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
10 Thermal Performance
Temperature measurements of key components were taken using t-type thermocouples.
The thermocouples were soldered directly to a Source pin of the TNY278PN device and
to the cathode of the output rectifier. The thermocouples were glued to the external core
and winding surfaces of transformer T1.
The unit was sealed inside a large box to eliminate any air currents. The box was placed
inside a thermal chamber. The ambient temperature within the large box was raised to
50 °C. The unit was then operated at full load and the temperature measurements were
taken after they stabilized for 1 hour at 50 °C.
Temperature (°C)
Item
85 VAC
265 VAC
Ambient inside the box
50
*
50*
TNY278PNP (U1)
95
92
Transformer winding(T1)
83
88
Transformer core (T1)
74
81
Output Rectifier (D7)
99
101
*To simulate operation inside sealed enclosure at 40 °C external ambient.
These results show that all key components have an acceptable rise in temperature.
Figure 11 – Infrared Thermograph of Open Frame Operation, at Room Temperature.
Cursor indicatesplastic temperature of U1
Page 25 of 34
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
23-Jul-09
11 Waveforms
11.1 Drain Voltage and Current, Normal Operation
Figure 12 – 115 VAC, Full Load.
Upper: IDRAIN, 0.4 A / div.
Lower: VDRAIN, 50 V / div, 2 µs / div.
Figure 13 – 230 VAC, Full Load.
Upper: IDRAIN, 0.4 A / div.
Lower: VDRAIN, 100 V / div. 2 µs / div
Figure 14 – 115 VAC, Full Load.
VDRAIN, 50 V, 20 µs / div.
Figure 15 – 230 VAC, Full Load.
VDRAIN, 100 V, 20 µs / div.
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23-Jul-09
DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
11.2 Output Voltage Start-Up Profile
Start-up into full resistive load and no-load were both verified. A 12 Ω resistor was used
for the load, to maintain 1 A under steady-state conditions.
Figure 16 – Start-Up Profile, 115 VAC.
Fast Trace is No-load Rise Time
Slower Trace is Maximum Load
2 V, 5 ms / div.
Figure 17 – Start-Up Profile, 230 VAC.
Fast Trace is No-load Rise Time
Slower Trace is Maximum Load
2 V, 5 ms / div.
11.3 Drain Voltage and Current Start-Up Profile
Figure 18 – 85VAC Input and Maximum Load.
Upper: VDRAIN, 100 V & 200 µs / div.
Lower: IDRAIN, 0.4 A / div.
Page 27 of 34
Figure 19 – 265 VAC Input and Maximum Load.
Upper: VDRAIN, 200 V & 200 µs / div.
Lower: IDRAIN, 0.4 A / div.
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
23-Jul-09
11.4 Load Transient Response (75% to 100% Load Step)
Figure 20 – Transient Response, 115 VAC,
50-100-50% Load Step.
Upper: VOUT 50 mV / div.
Lower: IOUT 0.4 A, 0.5 ms / div.
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Figure 21 – Transient Response, 230 VAC,
50-100-50% Load Step.
Upper: VOUT 50 mV / div.
Lower: IOUT 0.4 A, 0.5 ms / div.
Page 28 of 34
23-Jul-09
DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
11.5 Output Ripple Measurements
11.5.1 Ripple Measurement Technique
A modified oscilloscope test probe was used to take output ripple measurements, in order
to reduce the pickup of spurious signals. Using the probe adapter pictured in Figure 22,
the output ripple was measured with a 1 µF electrolytic, and a 0.1 µF ceramic capacitor
connected as shown.
Probe Ground
Probe Tip
Figure 22 – Oscilloscope Probe with Probe Master (www.probemaster.com) 4987A BNC Adapter.
(Modified with wires for ripple measurement, and two parallel decoupling capacitors added)
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
23-Jul-09
11.5.2 Measurement Results
The maximum voltage ripple at the output terminals of the power supply was measured
as 58 mV.
Figure 23 – Ripple, 85 VAC, Full Load.
20 µs, 50 mV / div.
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Figure 24 – Ripple, 115 VAC, Full Load.
20 µs, 50 mV / div.
Page 30 of 34
23-Jul-09
DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
12 Conducted EMI
Conducted emissions tests were performed at 115 VAC and 230 VAC at full load (12 V,
1.25 A). Measurements were taken with both Artificial Hand connection to output return
and output return floating. In both cases a resistor load was used connected at the end
of an output cable.
Composite EN55022B / CISPR22B conducted limits are shown. In all cases there was
excellent (>10 dB) margin.
12.1 115 VAC, Full Load
Line
Neutral
Artificial Hand Connected to Output Return
Artificial Hand Connected to Output Return
Output Floating
Output Floating
Figure 25– Conducted EMI at 115 VAC.
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
23-Jul-09
12.2 230 VAC, Full Load
Line
Neutral
Artificial Hand Connected to Output Return
Artificial Hand Connected to Output Return
Output Floating
Output Floating
Figure 26 – Conducted EMI at 230 VAC.
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23-Jul-09
DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
13 Revision History
Date
23-Jul-09
Page 33 of 34
Author
PL
Revision
1.0
Description & Changes
Initial Release
Reviewed
Apps
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DER-228 - 15 W, 12 V Supply with <30 mW No-load Input Power
23-Jul-09
For the latest updates, visit our website: www.powerint.com
Power Integrations reserves the right to make changes to its products at any time to improve reliability or
manufacturability. Power Integrations does not assume any liability arising from the use of any device or circuit
described herein. POWER INTEGRATIONS MAKES NO WARRANTY HEREIN AND SPECIFICALLY DISCLAIMS ALL
WARRANTIES INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT OF THIRD PARTY RIGHTS.
PATENT INFORMATION
The products and applications illustrated herein (including transformer construction and circuits external to the products)
may be covered by one or more U.S. and foreign patents, or potentially by pending U.S. and foreign patent applications
assigned to Power Integrations. A complete list of Power Integrations’ patents may be found at www.powerint.com.
Power Integrations grants its customers a license under certain patent rights as set forth at
http://www.powerint.com/ip.htm.
The PI Logo, TOPSwitch, TinySwitch, LinkSwitch, DPA-Switch, PeakSwitch, EcoSmart, Clampless, E-Shield, Filterfuse, StackFET,
PI Expert and PI FACTS are trademarks of Power Integrations, Inc. Other trademarks are property of their respective
companies. ©Copyright 2009 Power Integrations, Inc.
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