Title
Engineering Prototype Report for EP-68 –
6.6 W DC-DC Flyback Converter Using
DPA-Switch™ (DPA423G)
Specification Input: 36-57 VDC, Output: 3.3 V / 2 A
Application
Power over Ethernet (PoE) Power Supply
Author
Power Integrations Applications Department
Document
Number
EPR-68
Date
19-Jul-2005
Revision
1.1
Summary and Features
• High efficiency, low parts count and low cost power supply
• Ideally suited for PoE, VoIP, standby and other distributed 48 V DC-DC
conversion applications
• Signature circuit is fully compatible with IEEE 802.3af requirements
• DPA-Switch Integrates
• PWM controller and 220 V MOSFET switching device
• Accurate input voltage UV detection and OV protection
• Thermal, overload, short-circuit and open loop protection
• Regulation at zero load (cycle skipping)
• Accurate 400 kHz trimmed internal oscillator
• Small footprint 2" × 1", low overall height 0.9", dual layer PCB
• 100% surface mount construction
The products and applications illustrated herein (including circuits external to the products and transformer
construction) 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
5245 Hellyer Avenue, San Jose, CA 95138 USA.
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
EP68 3.3 V, 2 A DC-DC Power Supply
19-Jul-2005
Table Of Contents
1
2
3
4
Introduction..................................................................................................................3
Power Supply Specification .........................................................................................4
Schematic ...................................................................................................................5
Circuit Description .......................................................................................................6
4.1
DPA-Switch Primary ............................................................................................6
4.2
Output Rectification .............................................................................................6
4.3
Output Feedback.................................................................................................7
5 PCB Layout .................................................................................................................7
6 Bill of Materials ............................................................................................................8
7 Transformer Specification ...........................................................................................9
7.1
Electrical Diagram ...............................................................................................9
7.2
Electrical Specifications.......................................................................................9
7.3
Materials..............................................................................................................9
7.4
Transformer Build Diagram ...............................................................................10
7.5
Transformer Construction..................................................................................10
8 Transformer Spreadsheet .........................................................................................11
9 Performance Data .....................................................................................................13
9.1
Efficiency ...........................................................................................................13
9.2
Regulation .........................................................................................................14
9.2.1 Load...............................................................................................................14
9.2.2 Line ................................................................................................................14
9.3
Peak Power .......................................................................................................15
10 Waveforms ................................................................................................................15
10.1 Drain Voltage and Current, Full Load Operation ...............................................15
10.2 Output Voltage Start-Up Profile .........................................................................16
10.3 Drain Voltage and Current Start-Up Profile .......................................................16
10.4 Load Transient Response (75% to 100% Load Step) .......................................17
10.5 Output Ripple Measurements............................................................................18
10.5.1 Ripple Measurement Technique ....................................................................18
10.5.2 Output Ripple Measurements ........................................................................19
11 Thermal Performance................................................................................................20
12 Control Loop Measurements .....................................................................................22
12.1 36 VDC Maximum and Nominal Load ...............................................................22
12.2 57 VDC Maximum Load ....................................................................................23
13 Revision History ........................................................................................................24
Important Note:
Although this board is designed to satisfy safety telecom isolation requirements, this
engineering prototype has not been agency approved.
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
Page 2 of 28
19-Jul-2005
EP68 3.3 V, 2 A DC-DC Power Supply
1 Introduction
This engineering report describes a 3.3 V / 2 A (6.6 W) DC-DC converter that is based on
a DPA423G device. This design is intended as an evaluation platform for DPA-Switch
devices in the low cost surface-mount DIP package. High operating efficiency, low parts
count, small footprint and low height make this an ideal choice for Power over Ethernet
(PoE) and VoIP DC-DC converter applications.
This report contains the power supply specification, schematic, bill of materials,
transformer documentation, printed circuit board layout, and performance data.
Figure 1 - EP68 Populated Circuit Board Photograph.
Page 3 of 28
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
EP68 3.3 V, 2 A DC-DC Power Supply
19-Jul-2005
2 Power Supply Specification
Description
Symbol
Min
VIN
36
VOUT1
3.20
Output Ripple Voltage
Continuous Output Current
Peak Output Current
VRIPPLE1
IOUT
IOUT
2.0
Total Output Power
Continuous Output Power
Peak Output Power
POUT
POUT_PEAK
Input
Voltage
Output
Output Voltage
η
Efficiency
Typ
Max
Units
Comment
57
VDC
PoE input range specification
3.30
3.40
V
±3% including set point and
line/load regulation
35
50
mVpp
A
A
20 MHz bandwidth
6.6
8.3
W
W
78
%
2.5
77
Measured at 48 V,
o
POUT (6.6 W), 25 C
Environmental
Safety Isolation
Ambient Temperature
1500
TAMB
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
0
VDC
50
o
C
1 min.
Free convection, sea level
Page 4 of 28
19-Jul-2005
EP68 3.3 V, 2 A DC-DC Power Supply
3 Schematic
*All resistors and capacitors are 0805 size unless otherwise specified
Figure 2 - EP68 Schematic.
Page 5 of 28
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
EP68 3.3 V, 2 A DC-DC Power Supply
19-Jul-2005
4 Circuit Description
The Flyback topology was used to minimize circuit board size, parts count and cost, while
attaining excellent operating efficiency across the input voltage range.
4.1 DPA-Switch Primary
The DPA423G IC provides PWM control, startup, feedback, under/over voltage and overtemperature protection functions. The integrated 220 V MOSFET provides excellent
switching characteristics at the selected 400 kHz operating frequency. The MOSFET and
controller consume minimal power, enabling a typical operating efficiency of 74%-78%
across the operating input voltage range (see Figure 7).
R1 provides a 25 kΩ input impedance, consistent with PoE Class 0 requirements. Above
30 V, Zener VR1 conducts, allowing n-channel MOSFET Q1 to turn on. Zener diode VR2
protects the gate of Q1 from overvoltage damage. Resistors R2 and R3 provide
repeatable on and off timing.
Resistor R5 programs the typical input under-voltage ON threshold to 33 VDC. Resistors
R4 and R6 program the internal device current limit to reduce with increasing input
voltage. Maximum output (overload) current varies less than 5% across the operating
voltage range. The reduction in overload output current reduces secondary transformer
leakage spikes and allows the use of a 30 V Schottky diode, for the output rectifier D1.
The primary-side Zener clamp, VR3, provides protection of the DPA423G drain under
input surge and overvoltage conditions. Zener diode VR3 does not conduct under normal
operating conditions.
The primary bias winding provides CONTROL pin current after start-up. Diode D2
rectifies the bias winding, while components R8 and C11 reduce the high frequency
switching noise and reduce the peak charging of the bias voltage.
The DPA423G operates well within the recommended junction temperature limits
(100 °C) at an elevated ambient of 50 °C, in a free-convection cooled environment (see
Section 11).
4.2 Output Rectification
Schottky output diode D1 enables low-loss rectification of the secondary winding voltage.
Low ESR tantalum output capacitors, C7-9, reduce switching ripple and minimize losses.
Secondary output choke L1 and ceramic output capacitor C10 reduce high frequency
noise and ripple at the output.
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
Page 6 of 28
19-Jul-2005
EP68 3.3 V, 2 A DC-DC Power Supply
4.3 Output Feedback
The output voltage is sensed via the resistor divider formed by R12 and R13 and fed into
the reference pin of the low voltage reference, U3. Feedback compensation components
R10, R11, and C13 ensure stable operation and optimum line and load transient
response. Capacitor C12 provides a soft-finish characteristic, preventing output voltage
overshoot during startup of the converter.
5 PCB Layout
Figure 3 - Top Side, SMT Printed Circuit Layout (Top View).
Figure 4 - Bottom Side, SMT Printed Circuit Layout (Top View).
Page 7 of 28
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
EP68 3.3 V, 2 A DC-DC Power Supply
19-Jul-2005
6 Bill of Materials
Item
Qty
Reference
Description
P/N
Manufacturer
1
2
1
1
U1
U2
DPA423G
PC357N1TA
Power Integrations
Sharp
3
1
U3
CAT431L
Catalyst Semiconductor
4
5
6
7
8
9
10
1
1
1
2
1
3
1
C1, C2
C3
C4
C5, C13
C6
C7-9
C10
THCS50E2A155ZT
ECJ-2VC2D470J
1808SC102KAT1A
ECJ-2YB1H104K
ECST1AC226R
T495X337K006AS
ECY-29RA105KV
UCC
Panasonic
AVX
Panasonic
Panasonic
Kemet
Panasonic
11
12
13
14
15
1
1
1
1
4
ECJ-3FF1H105Z
ECJ-2YB1C334K
SL43
BAV21
4531051-0000
Panasonic
Panasonic
Vishay
generic
Zierick
16
17
18
1
1
1
C11
C12
D1
D2
J1-1,2
J2-1,2
L1
L2
Q1
SCD-0403-100MT
SCD-0403-1R0M
Si2328DS-T1
Chilisin
Chilisin
Vishay
19
20
21
22
23
24
25
26
27
28
29
30
31
32
1
1
1
1
1
1
1
1
1
1
1
1
1
1
R1
R2
R3
R4
R5
R6
R7
R8
R9
R10
R11
R12
R13
T1
DPA-Switch
Optocoupler, 80-160% graded
CTR
Low voltage shunt regulator,
SOT23
1.5 µF, 100 V, 1812
47 pF, 200 V
1000 pF, 1500V, 1808
0.1 µF, 50 V
22 µF, 10 V, tantalum, C size
330 µF, 6.3 V, tantalum, X size
1 µF, 10 V, 0508 alternative
geometry
1 µF, 50 V, 1206
0.33 µF, 50 V
30 V, 4 A Schottky
200 V, 200 mA
Pin, Surface Mount,
0.040 x 0.375”
10 µH, 1 A
1 µH, 2 A
MOSFET, N Channel, 100 V,
250 mΩ
24.9 kΩ, 1%, 1206
51 kΩ
249 kΩ
1.00 MΩ, 1%
619 kΩ, 1%
8.66 kΩ, 1%
10 Ω
100 Ω
5.1 Ω
75 Ω
1 kΩ
34.0 kΩ, 1%
20.0 kΩ, 1%
ER14.5 Transformer
33
34
35
1
1
1
VR1
VR2
VR3
27V, 500 mW, SOD123
15V, 200 mW, SOD323
150V TVS
ERJ-8ENF2492V
ERJ-6GEYJ513V
ERJ-6GEY2493V
ERJ-6ENF1004V
ERJ-6ENF6193V
ERJ-6ENF8661V
ERJ-6GEYJ100V
ERJ-6GEYJ101V
ERJ-6GEYJ5R1V
ERJ-6GEYJ750V
ERJ-6GEYJ102V
ERJ-6ENF3402V
ERJ-6ENF2002V
LSTA30825
SIL6029
IM 040 202 31
BZT52C27-7
BZT52C15S-7
SMAJ150A
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
Panasonic
L.S.E.
HiCal
Vogt
Diodes, Inc. or Generic
Diodes, Inc. or Generic
Generic
*Resistors and capacitors are size 0805, unless otherwise specified.
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
Page 8 of 28
19-Jul-2005
EP68 3.3 V, 2 A DC-DC Power Supply
7 Transformer Specification
7.1
Electrical Diagram
ER14.5 3C96 / 3F3,
10 pin Bobbin
1
9,10
WDG #4
10T #34 AWG
WDG #3
2T #28 AWG x2
2
6,7
4
WDG #1
10T #34 AWG
WDG #2
8T #34 AWG
3
5
Figure 5 - Transformer Electrical Diagram.
7.2
Electrical Specifications
Electrical Strength
Primary Inductance
Resonant Frequency
Primary Leakage Inductance
7.3
1 second, 60 Hz, from Pins 1-5 to Pins 6-10
Pins 1-3, all other windings open
Pins 1-3, all other windings open
Pins 1-3, with Pins 6/7-9/10 shorted
1500 VDC
120 µH,
+/-10%
7.5 MHz (min.)
3.0 µH (max.)
Materials
Item
[1]
[2]
[3]
[4]
[5]
[6]
[7]
Description
Core: ER14.5, Ferroxcube 3C96, 3F3 (or equivalent), ALG = 312 nH/T2
Bobbin: ER14.5, 10 pin
Magnet Wire: #34 AWG, Double Coated (Heavy Nyleze)
Magnet Wire: #28 AWG, Double Coated (Heavy Nyleze)
Tape: 3M 1298 Polyester Film (or equivalent), 1.8 mm wide
Core Clamp ER14.5 Ferroxcube CLM14.5 (optional)
Varnish (DIPPED ONLY, NOT IMPREGNATED)
Page 9 of 28
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
EP68 3.3 V, 2 A DC-DC Power Supply
7.4
19-Jul-2005
Transformer Build Diagram
Pin Side
Tape
1
1/2 Primary
Tape
6,7
Secondary
9,10
Tape
5
4
Bias
2
3
1/2 Primary
Figure 6 - Transformer Build Diagram.
7.5
Transformer Construction
Bobbin Preparation
½ Primary
Bias Winding
Basic Insulation
Secondary Winding
Basic Insulation
½ Primary
Outer Insulation
Final Assembly
Arrange bobbin & rotation such that primary start/finish wires do not
overlap.
Start at Pin 3. Wind 10 turns of item [3] in 1 layer. Bring finish lead back
and terminate on Pin 2.
Starting at Pin 4, wind 8 turns of item [3]. Spread turns evenly across
bobbin in a single layer. Bring finish lead back and terminate on Pin 5.
Use one layer of item [5] for basic insulation.
Start at Pins 9 and 10. Wind 2 turns of bifilar item [4] in 1 layer. Bring
finish lead back and terminate on Pins 6 and 7.
Use one layer of item [5] for basic insulation.
Continue from Pin 2. Wind 10 turns of item [3] in 1 layer. Bring finish lead
back and terminate on Pin 1.
Use one layer of item [5] for basic insulation.
Assemble and secure (glue or clamp, item[6]) core halves.
Dip varnish item [7] and cure.
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
Page 10 of 28
19-Jul-2005
EP68 3.3 V, 2 A DC-DC Power Supply
8 Transformer Spreadsheet
Page 11 of 28
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
EP68 3.3 V, 2 A DC-DC Power Supply
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
19-Jul-2005
Page 12 of 28
19-Jul-2005
EP68 3.3 V, 2 A DC-DC Power Supply
9 Performance Data
All measurements were taken at room temperature utilizing a DC input source and
dynamic DC loads. Input and output voltages and output current were measured with
dedicated DVMs.
9.1
Efficiency
Efficiency Vs. Output Load
80%
79%
78%
Efficiency (%)
77%
VIN=36 VDC
VIN=48 VDC
VIN=57 VDC
76%
75%
74%
73%
72%
71%
70%
0.50
0.75
1.00
1.25
1.50
1.75
2.00
Load Current (A)
Figure 7 - Efficiency vs Output Load, Room Temperature.
Page 13 of 28
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
EP68 3.3 V, 2 A DC-DC Power Supply
9.2
19-Jul-2005
Regulation
9.2.1 Load
Load Regulation
Output Voltage (VDC)
3.40
3.35
VIN=36 VDC
3.30
VIN=48 VDC
VIN=57 VDC
3.25
3.20
0.0
0.3
0.5
0.8
1.0
1.3
1.5
1.8
2.0
Load Current (A)
Figure 8 - Load Regulation, Room Temperature.
9.2.2 Line
Line Regulation
Output Voltage (VDC)
3.40
3.35
Full Load (2 A)
50% Load (1 A)
3.30
No Load
3.25
3.20
30.0
40.0
50.0
60.0
Input Voltage (VDC)
Figure 9 - Line Regulation, Room Temperature.
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
Page 14 of 28
19-Jul-2005
EP68 3.3 V, 2 A DC-DC Power Supply
9.3 Peak Power
The DC output load current was recorded just prior to the auto-restart operation.
Maximum Output Current
3.00
Output Current (A)
2.90
2.80
2.70
2.60
2.50
30.0
40.0
50.0
60.0
Input Voltage (VDC)
Figure 10 - Maximum Output Overload Current, Room Temperature.
10 Waveforms
10.1 Drain Voltage and Current, Full Load Operation
Figure 11 – 36 VDC, Full Load.
Upper: IDRAIN, 0.5 A / div.
Lower: VDRAIN, 50 V, 1 µs / div.
Page 15 of 28
Figure 12 – 57 VDC, Full Load.
Upper: IDRAIN, 0.5 A / div.
Lower: VDRAIN, 50 V, 1 µs / div.
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
EP68 3.3 V, 2 A DC-DC Power Supply
19-Jul-2005
10.2 Output Voltage Start-Up Profile
Figure 13 - Start-Up Profile, 36 VDC, No Load
(worst-case).
Upper: VOUT, 1 V / div.
Lower: VDRAIN, 50 V, 10 ms / div.
Figure 14 - Start-Up Profile, 57 VDC, No Load
(worst-case).
Upper: VOUT, 1 V / div.
Lower: VDRAIN, 50 V, 10 ms / div.
10.3 Drain Voltage and Current Start-Up Profile
Figure 15 – 36 VDC Input, 2 A Resistive Load.
Upper: IDRAIN, 0.5 A / div.
Lower: VDRAIN, 100 V, 10 ms / div.
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
Figure 16 – 57 VDC Input, 2 A Resistive Load.
Upper: IDRAIN, 0.5 A / div.
Lower: VDRAIN, 100 V, 10 ms / div.
Page 16 of 28
19-Jul-2005
EP68 3.3 V, 2 A DC-DC Power Supply
10.4 Load Transient Response (75% to 100% Load Step)
In the following two oscilloscope screen shots (Figures 17 and 18), signal averaging was
used to more clearly capture the output voltage response to a load transient. Averaging
minimizes the appearance of the 400 kHz switching ripple in the output voltage scope
plot. The load current step was used to trigger the horizontal sweep of the oscilloscope.
Figure 17 - Transient Response,
36 VDC, 75-100-75% Load Step.
Top: Load Current, 1 A / div.
Bottom: Output Voltage,
20 mV, 500 µs / div.
Page 17 of 28
Figure 18 - Transient Response,
57 VDC, 75-100-75% Load Step.
Top: Load Current, 1 A / div.
Bottom: Output Voltage,
20 mV, 500 µs / div.
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
EP68 3.3 V, 2 A DC-DC Power Supply
19-Jul-2005
10.5 Output Ripple Measurements
10.5.1 Ripple Measurement Technique
For DC output ripple measurements, a modified oscilloscope test probe must be utilized
in order to reduce spurious signals due to pickup. Details of the probe modification are
provided in Figures 19 and 20.
The 5125BA probe adapter is affixed with two capacitors tied in parallel across the probe
tip. The capacitors include one (1) 0.1 µF/50 V ceramic type and one (1) 1.0 µF/50 V
aluminum electrolytic. The aluminum electrolytic type capacitor is polarized, so
proper polarity across DC outputs must be maintained (see below).
Probe Ground
Probe Tip
Figure 19 - Oscilloscope Probe Prepared for Ripple Measurement (End Cap and Ground Lead Removed).
Figure 20 - Oscilloscope Probe with Probe Master 5125BA BNC Adapter (Modified with Wires for Probe
Ground for Ripple Measurement, and Two Parallel Decoupling Capacitors Added).
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
Page 18 of 28
19-Jul-2005
EP68 3.3 V, 2 A DC-DC Power Supply
10.5.2 Output Ripple Measurements
Figure 21 - Ripple, 36 VDC, Full Load.
Top: 10 mV / div, 50 µs / div.
Bottom: 10 mV / div, 2 µs / div.
Figure 22 - Ripple, 48 VDC, Full Load.
Top: 10 mV / div, 50 µs / div.
Bottom: 10 mV / div, 2 µs / div.
Figure 23 - Ripple, 57 VDC, Full Load.
Top: 10 mV / div, 50 µs / div.
Bottom: 10 mV / div, 2 µs / div.
Page 19 of 28
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
EP68 3.3 V, 2 A DC-DC Power Supply
19-Jul-2005
11 Thermal Performance
The temperatures of key components were recorded using T-type thermocouples. Two
of the four thermocouples were soldered; one directly to a SOURCE pin of the DPA423G
(U1) and the other to the cathode of the output rectifier (D1). The other two
thermocouples were glued; one to the transformer (T1) core, on the center leg, and the
other to the case of the first (of the two) high-ripple output capacitor (C7).
The unit was operated at full load, at 36 VDC, 48 VDC and 57 VDC, in free convection
within a small enclosure.
The results show adequate thermal margin, considering an additional ambient rise of
+28 °C, equivalent to operating at an ambient of 50 °C. At 36 VDC, full load, within an
enclosure at 50 °C ambient, this equates to a DPA423G case temperature of 79 °C. This
is well below the recommended maximum case temperature of 100 °C.
Figure 24 is an infrared thermograph taken at nominal-line (48 VDC).
Measured Temperature (°C)
Item
36 VDC
48 VDC
57 VDC
Ambient
22
22
22
DPA423G (U1)
51
51
53
Transformer core (T1)
75
75
75
Output Rectifier (D1)
63
61
61
Output Capacitor (C7)
45
43
43
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
Page 20 of 28
19-Jul-2005
EP68 3.3 V, 2 A DC-DC Power Supply
TOP VIEW
BOTTOM VIEW
Figure 24- Infrared Thermograph of the EP68 Board, 48 VDC, Full Load, Room Ambient.
Page 21 of 28
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
EP68 3.3 V, 2 A DC-DC Power Supply
19-Jul-2005
12 Control Loop Measurements
12.1 36 VDC Maximum and Nominal Load
Figure 25 - Gain-Phase Plot, 36 VDC, Maximum Load (2 A).
Vertical Scale: Gain = 10 dB / div, Phase = 30° / div.
Crossover Frequency = 10.0 kHz, Phase Margin = 60°
Figure 26 - Gain-Phase Plot, 36 VDC, Light Load (100 mA).
Vertical Scale: Gain = 10 dB / div, Phase = 30° / div.
Crossover Frequency = 0.9 kHz, Phase Margin = 65°
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
Page 22 of 28
19-Jul-2005
EP68 3.3 V, 2 A DC-DC Power Supply
12.2 57 VDC Maximum Load
Figure 27 - Gain-Phase Plot, 57 VDC, Light Load (100 mA).
Vertical Scale: Gain = 10 dB / div, Phase = 30° / div.
Crossover Frequency = 10.8 kHz, Phase Margin = 40°
Figure 28 - Gain-Phase Plot, 57 VDC, Light Load (100 mA).
Vertical Scale: Gain = 10 dB / div, Phase = 30° / div.
Crossover Frequency = 0.9 kHz, Phase Margin = 60°
The results indicate adequate loop bandwidth and significant gain and phase margin.
Page 23 of 28
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
EP68 3.3 V, 2 A DC-DC Power Supply
19-Jul-2005
13 Revision History
Date
25-Feb-04
02-Mar-04
15-Mar-04
19-Jul-05
Author
SH
PV
PV
PV
Revision
0.1
0.2
1.0
1.1
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
Description & changes
First release
Second release after minor edits
Final release
Fixed schematic and bill of materials (BOM)
Page 24 of 28
19-Jul-2005
EP68 3.3 V, 2 A DC-DC Power Supply
Notes
Page 25 of 28
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
EP68 3.3 V, 2 A DC-DC Power Supply
19-Jul-2005
Notes
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
Page 26 of 28
19-Jul-2005
EP68 3.3 V, 2 A DC-DC Power Supply
Notes
Page 27 of 28
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
EP68 3.3 V, 2 A DC-DC Power Supply
19-Jul-2005
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, EcoSmart, PI Expert and PI FACTS are trademarks
of Power Integrations, Inc. Other trademarks are property of their respective companies. ©Copyright 2005 Power Integrations, Inc.
Power Integrations Worldwide Sales Support Locations
WORLD HEADQUARTERS
5245 Hellyer Avenue
San Jose, CA 95138, USA.
Main:
+1-408-414-9200
Customer Service:
Phone:
+1-408-414-9665
Fax:
+1-408-414-9765
e-mail: usasales@powerint.com
GERMANY
Rueckertstrasse 3
D-80336, Munich
Germany
Phone:
+49-89-5527-3910
Fax:
+49-89-5527-3920
e-mail: eurosales@powerint.com
JAPAN
Keihin Tatemono 1st Bldg
2-12-20
Shin-Yokohama, Kohoku-ku,
Yokohama-shi, Kanagawa ken,
Japan 222-0033
Phone:
+81-45-471-1021
Fax:
+81-45-471-3717
e-mail:
japansales@powerint.com
TAIWAN
5F, No. 318, Nei Hu Rd., Sec. 1
Nei Hu Dist.
Taipei, Taiwan 114, R.O.C.
Phone:
+886-2-2659-4570
Fax:
+886-2-2659-4550
e-mail:
taiwansales@powerint.com
CHINA (SHANGHAI)
Rm 807-808A,
Pacheer Commercial Centre,
555 Nanjing Rd. West
Shanghai, P.R.C. 200041
Phone:
+86-21-6215-5548
Fax:
+86-21-6215-2468
e-mail: chinasales@powerint.com
INDIA
261/A, Ground Floor
7th Main, 17th Cross,
Sadashivanagar
Bangalore, India 560080
Phone:
+91-80-5113-8020
Fax:
+91-80-5113-8023
e-mail: indiasales@powerint.com
KOREA
RM 602, 6FL
Korea City Air Terminal B/D,
159-6
Samsung-Dong, Kangnam-Gu,
Seoul, 135-728, Korea
Phone:
+82-2-2016-6610
Fax:
+82-2-2016-6630
e-mail:
koreasales@powerint.com
EUROPE HQ
1st Floor, St. James’s House
East Street, Farnham
Surrey, GU9 7TJ
United Kingdom
Phone:
+44 (0) 1252-730-140
Fax:
+44 (0) 1252-727-689
e-mail: eurosales@powerint.com
CHINA (SHENZHEN)
Room 2206-2207, Block A,
Elec. Sci. Tech. Bldg.
2070 Shennan Zhong Rd.
Shenzhen, Guangdong,
China, 518031
Phone:
+86-755-8379-3243
Fax:
+86-755-8379-5828
e-mail: chinasales@powerint.com
ITALY
Via Vittorio Veneto 12
20091 Bresso MI
Italy
Phone: +39-028-928-6000
Fax: +39-028-928-6009
e-mail: eurosales@powerint.com
SINGAPORE
51 Newton Road,
#15-08/10 Goldhill Plaza,
Singapore, 308900
Phone:
+65-6358-2160
Fax:
+65-6358-2015
e-mail:
singaporesales@powerint.com
APPLICATIONS HOTLINE
World Wide +1-408-414-9660
Power Integrations
Tel: +1 408 414 9200 Fax: +1 408 414 9201
www.powerint.com
APPLICATIONS FAX
World Wide +1-408-414-9760
Page 28 of 28