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TOP245P_1中文资料

Power Integrations, Inc.

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Design Example Report

Title

32W (47W peak) Multiple Output supply using TOP245P

Specification Input: 195 - 265 VAC

Output: 3.3V/3A, 5V/2A (2.5A Peak),

12V/0.5A (1.5A Peak), 20V/0.3A Application Set Top Box

Author Power Integrations Applications Department Document Number DER-19 Date March 30, 2004 Revision

1.0

Summary and Features

This report describes a design for a multiple output power supply, such as required for a Set Top Box, featuring the following:

? Very high full power efficiency (> 83% at full power) ? 32W Continuous power rating ? <0.5W no-load consumption

? Efficiency >75% at 10% output power

? Small DIL08 package for TOP245P requiring no external heatsink

? 50W peak power capability allows for high peak output power demands (e.g. for hard disk spin-up)

? Low EMI (Meets EN55022 with output ground connected to Earth)

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 https://www.wendangku.net/doc/f813173985.html, .

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Table Of Contents

1 Introduction................................................................................................................4

2 Power Supply Specification........................................................................................5

3 Schematic..................................................................................................................6 4

Circuit Description......................................................................................................7 4.1 Input EMI Filtering...............................................................................................7 4.2 TOPSwitch Primary.............................................................................................7 4.3 Output Rectification.............................................................................................7 4.4 Output Feedback ................................................................................................7 5 PCB Layout................................................................................................................8 6 Bill Of Materials..........................................................................................................9 7 Transformer Specification........................................................................................10 7.1 Electrical Diagram.............................................................................................10 7.2 Electrical Specifications....................................................................................10 7.3 Materials...........................................................................................................10 7.4 Transformer Build Diagram...............................................................................11 7.5 Transformer Construction.................................................................................11 8 Transformer Spreadsheets ......................................................................................12 9 Performance Data....................................................................................................15 9.1 Efficiency...........................................................................................................15 9.2 No-load Input Power.........................................................................................16 9.3 Peak Power.......................................................................................................16 9.4 Regulation.........................................................................................................16 9.4.1 Load...........................................................................................................16 9.4.2 Line............................................................................................................17 9.5 Cross Regulation ..............................................................................................17 10 Thermal Performance...........................................................................................18 11 Waveforms...........................................................................................................18 11.1 Drain Voltage and Current, Normal Operation..................................................18 11.2 Output Voltage Start-up Profile (Full Power).....................................................19 11.3 Drain Voltage and Current Start-up Profile .......................................................20 11.4 Load Transient Response.................................................................................20 11.5 Output Ripple Measurements...........................................................................21 11.5.1 Ripple Measurement Technique................................................................21 11.5.2 Measurement Results................................................................................22 12 Conducted EMI.....................................................................................................24 13 Revision History. (25)

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https://www.wendangku.net/doc/f813173985.html, Table Of Figures

Figure 1 – Populated Circuit Board (Scale in cm) (4)

Figure 2– TOP245P Schematic for 32W cont / 46W peak (6)

Figure 3 – Printed Circuit Layout (Scale not 1:1) (8)

Figure 4 –Transformer Electrical Diagram (10)

Figure 5 – Transformer Build Diagram (11)

Figure 6- Full Continuous Power Conversion Efficiency (15)

Figure 7 - Efficiency Variation with Load (15)

Figure 8 – Load Regulation, Room Temperature, 230V AC Input (16)

Figure 9 – Line Regulation, Room Temperature, Full Load (17)

Figure 10 - Cross Regulation (17)

Figure 11 - Key Component Temperature Rise variation with Line Voltage (18)

Figure 12 - 195 V AC, Full Continuous Load (18)

Figure 13 - 265 VAC, Full Continuous Load (18)

Figure 14 -Start-up Profile, 230V AC (19)

Figure 15 - Start-up Profile, 230V AC (19)

Figure 16 - Start-up Profile, 230V AC (19)

Figure 17 - 195 V AC Input and Maximum Load (20)

Figure 18 - 265 VAC Input and Maximum Load (20)

Figure 19 – Transient Response, 230V AC, 3A to 4A Step load change on 3V3. Full Load.

(20)

Figure 20 - Oscilloscope Probe Prepared for Ripple Measurement (21)

Figure 21 - Oscilloscope Probe with Probe Master 5125BA BNC Adapter (21)

Figure 22 – 3V3 Ripple, 230 V AC, Full Load (22)

Figure 23 – 3V3 Switching Noise, 230 V AC, Full Load (22)

Figure 24 – 5V Ripple, 230 V AC, Full Load (22)

Figure 25 – 5V Switching Noise, 230 V AC, Full Load (22)

Figure 26 – 12V Ripple, 230 V AC, Full Load (23)

Figure 27 – 12V Switching Noise, 230 V AC, Full Load (23)

Figure 28 – 20V Rail Ripple, 230 V AC, Full Load (23)

Figure 29 – 20V Rail Switching Noise, 230 V AC, Full Load (23)

Figure 30 - Conducted EMI, Full Continuous Power, 230 V AC, and EN55022 B Limits (24)

Figure 31 - Conducted EMI, Full Continuous Power, 230 V AC, and EN55022 B Limits (24)

Important Notes:

Although this board is designed to satisfy safety isolation requirements, the engineering prototype has not been agency approved. Therefore, all testing should be performed using an isolation transformer to provide the AC input to the prototype board.

Design Reports contain a power supply design specification, schematic, bill of materials, and transformer documentation. Performance data and typical operation characteristics are included. Typically only a single prototype has been built.

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1 Introduction

This engineering report describes a multiple output evaluation board designed using TOP245P. The specification chosen is targeted towards new Set Top Box systems that incorporate a hard disk. These systems require a peak power capability when the hard disk is first spun-up.

Peak power operation requires magnetics and diodes specified to handle the currents at the specified peak power point. If peak power operation is not required, designing the supply for maximum continuous power will save additional cost.

The document contains the power supply specification, schematic, bill of materials, transformer documentation, printed circuit layout, and measured performance data from the prototype unit shown in Figure 1.

Figure 1 – Populated Circuit Board (Scale in cm)

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2 Power Supply Specification

Description

Symbol Min

Typ

Max

Units

Comment

Input Voltage V IN 195 265 VAC 2 Wire – no P.E.

Frequency f LINE 47 50/60 64 Hz

Output

Output Voltage 1

V OUT1 3.3 V

± 5% Output Ripple Voltage 1 V RIPPLE1 mV

20 MHz Bandwidth Output Current 1 I OUT1 1 3 A

Output Voltage 2 V OUT2 5 V ± 5% Output Ripple Voltage 2 V RIPPLE2

20 MHz Bandwidth Output Current 2 I OUT2 1 2 A 2.5A Peak for 10s

Output Voltage 3 V OUT3 12 V ± 7%

Output Ripple Voltage 3 V RIPPLE3

20 MHz Bandwidth Output Current 3 I OUT3 0.35 0.5 A 1.5A Peak for 10s

Output Voltage 4 V OUT4 20 V ± 7%

Output Ripple Voltage 4 V RIPPLE4

20 MHz Bandwidth

Output Current 4

I OUT4 0.1 0.3 0.3 A

Total Output Power

Continuous Output Power P OUT 31.9 W

Peak Output Power P OUT_PEAK

46.4 W

Efficiency η 75 %

Measured at P OUT (32 W), 25

o C Environmental

Conducted EMI

Meets CISPR22B / EN55022B

Safety Designed to meet IEC950, UL1950

Class II

Surge 4 kV 1.2/50 μs surge, IEC 1000-4-5,

12 ? series impedance, differential and common mode

Surge 3 kV

100 kHz ring wave, 500 A short circuit current, differential and common mode

Ambient Temperature T AMB 0 50 o

Free convection, sea level

Table 1 - Power Supply Specification

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3 Schematic

Figure 2– TOP245P Schematic for 32W cont / 46W peak

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4 Circuit Description

This power supply uses the latest generation TOPSwitch in a DIL08 package to minimize heatsink requirements. It is designed for 32W continuous operation in a 50°C ambient with magnetics designed to allow short peak power levels of up to 50W.

4.1 Input EMI Filtering

Due to the frequency jittering function of TOPSwitch, the input EMI filtering is minimal, consisting of a 15mH common-mode choke and 220nF x-capacitor. Protection is provided by a 1A, 250V antisurge fuse. Inrush limiting is provided by a thermistor. Surge protection is provided by a VDR on the input. If only 4kV surge is required, this part can be removed since the TOP245P incorporates over-voltage shutdown giving additional protection.

4.2 TOPSwitch Primary

On the primary side of the supply, the TOPSwitch integrates a number of functions:- Frequency jitter which reduces the QP and AV EMI levels by up to 10dB

Soft-Start which prevents transformer saturation during start-up. This increases long term reliability

Line UV and OV detection to give additional differential surge withstand capability Regulation to zero load without pre-load due to very low minimum duty cycle capability

Line feed forward which improves 100Hz ripple rejection

Hysteretic thermal and short circuit protection to increase long term reliability

A 47uF input capacitor has been used to provide the high peak power capability. If peak power operation is not required, this can be reduced to 33uF, 400V which will save further cost.

4.3 Output Rectification

A fully AC stacked design has been used to give good cross-regulation. A snubber is placed across D7 to reduce high frequency common-mode EMI emissions. Post filters are used on all outputs to meet noise and ripple requirements.

4.4 Output Feedback

Full PWM feedback has been implemented using a TL431 reference and opto-coupler. Feedback is split over the 3V3 and 5V rails, each giving equal influence to the feedback network. D10, R10 and C11 provide a soft-finish function, ensuring a monotonic rise in the output voltages with zero overshoot.

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5 PCB Layout

The evaluation board was implemented using a single copper layer. Figure 3 shows the component placement and underside copper routing.

Figure 3 – Printed Circuit Layout (Scale not 1:1)

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6 Bill Of Materials

Reference Quantity Value

R1,R221M

R316R8

R413k3

R5110k, 1%

R6122k, 1%

R716k8, 1%

R81150R

R911k

R10110k

R11120R, 2W NTC

R1213R3

C11220nF, X2 CAP

C2147uF, 400V

C3,C122100nF

C4147uF, 10V

C511000uF, 35V

C61470uF, 35V

C71100uF, 35V

C8,C92100uF, 10V

C10147uF, 16V

C11122uF, 10V

C131 2.2nF, Y1_CLASS

C1411uF, 50V

C15139uF, 35V

C16147uF, 35V

C1711nF, 1kV

C181 4.7nF

U11TL431

U21PC817

U31TOP245P

D1,D2,D3,D441N4007

D511N4937

D61P4KE200

D7,D82MBR1035

D91SR506

D101BAS19

D111IN4148

D121UF4002

FU111A, 250V

T11EF30 Custom Transformer

L21 4.7uH, 1A

L7,L8,L93 4.7uH, 3.2A

VDR11300V

Total of 52 components

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7 Transformer Specification

7.1 Electrical Diagram

Figure 4 –Transformer Electrical Diagram

7.2 Electrical Specifications

Electrical Strength 1 second, 60 Hz, from Pins 1-4 to Pins 7-12 3000 VAC Primary Inductance Pins 1-4, all other windings open, measured at 100 kHz, 0.4 VRMS

1180 μH, -0/+20% Resonant Frequency Pins 1-4, all other windings open

600 kHz (Min.) Primary Leakage Inductance

Pins 1-4, with Pins 7-8 shorted, measured at 100 kHz, 0.4 VRMS

50 μH (Max.)

7.3 Materials

Item Description

[1] Core: EF30 CORE, 3C85, Gapped for 234nH/T 2

(Approximately 0.28mm) [2] Bobbin: EF30, 10 pin [3] Magnet Wire: 0.24mm Diameter Heavy Nyleze [4] Copper Foil: See section below [5] Tape: 16mm wide insulation tape [6] Tape: 3mm margin tape [7] Magnet Wire: 0.45mm Diameter Heavy Nyleze [8] Varnish

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7.4 Transformer Build Diagram

Figure 5 – Transformer Build Diagram

7.5 Transformer Construction

Bobbin Preparation Place 3mm of Margin tape on each side of the EF30 Bobbin

? Primary

Start at Pin 4. Wind 36 turns of item [3] in approximately 1 layer. Bring

finish lead back to start. Finish on Pin 2.

Basic Insulation Use two layers of item [5] for basic insulation.

Bifilar Bias Winding

Starting at Pin 6, wind 9 bifilar turns of item [3]. Spread turns evenly

across bobbin. Finish at Pin 3.

Insulation Use three layers of item [5] for safety insulation.

3V3 and 5V

Windings

Start at Pins 7 and 8. Wind 2 turns of copper foil [4]. Bring termination

wire out onto pin 9. Continue with one further copper foil turn and finish

with termination on pin 10.

12V and 20V Windings Start at Pin 10. Wind 4 turns of 4 parallel strands of item [7] using half the

bobbin width. Terminate on pin 11. Continue with 4 further turns of 4 parallel strands of item [7] using the remaining half bobbin width. Finish

on pin 12.

? Primary

Start at Pin 2. Wind 35 turns of item [3] in approximately 1 layer. Bring

finish lead back to start. Finish on Pin 1.

Outer Wrap Wrap windings with 3 layers of tape item [5]. Final Assembly

Assemble and secure core halves. Varnish impregnate (item [8]).

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8 Transformer Spreadsheets

This design was produced using PIExpert assuming a TOP245P device with a current limit capability of 1.1A and an Rdson of 4?. The data below reflects the full continuous load, which gives approximately 0.7A peak primary current. The transformer has been designed to operate with safe flux levels with primary currents of up to 1.2A allowing for the peak power capability.

Power Supply Input

VACMIN Volts 195

Min Input AC Voltage VACMAX Volts 265 Max Input AC Voltage FL Hertz 50 AC Main Frequency TC mSeconds 1.81

Bridge Rectifier Conduction Time Estimate

Z 0.68

Loss Allocation Factor N % 74.0

Efficiency Estimate

Power Supply

Outputs

VOx Volts 3.30 5.00 12.00 20.00 Output Voltage

IOx Amps 3.000

2.000

0.500 0.300 Output Current

VB Volts 15.00 Bias Voltage IB Amps 0.006

Bias Current

Device Variables

Device

TOP245P

Device Name

PO Watts 31.99 Total Output Power

VDRAIN Volts 678

Maximum Drain Voltage Estimate (Includes Effect of Leakage Inductance)

FS Hertz 132000 Device Switching Frequency

KRPKDP 0.70 Ripple to Peak Current Ratio

1.00

External Current Limit Ratio

IP Amps 0.75

Peak Primary Current IRMS Amps 0.31 Primary RMS Current DMAX 0.36

Maximum Duty Cycle

Power Supply Components

Selection

CIN uFarads 47.0

Input Filter Capacitor

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VMIN Volts 247 Minimum DC Input

Voltage

VMAX Volts 375 Maximum DC Input

Voltage

VCLO Volts 200 Clamp Zener Voltage PZ Watts 2.0

VDB Volts 0.7 Bias Winding Diode

Forward Voltage Drop PIVB Volts 59 Bias Rectifier Maximum

Peak Inverse Voltage Power Supply Output

Parameters

VDx Volts 0.5 0.5 0.7 0.7 Output Winding Diode

Forward Voltage Drop PIVSx Volts 14 20 47 77 Output Rectifier

Maximum Peak Inverse

Voltage

ISPx Amps 7.74 5.16 1.29 0.77 Peak Secondary

Current

ISRMSx Amps 4.22 2.81 0.70 0.42 Secondary RMS

Current

IRIPPLEx Amps 2.96 1.97 0.49 0.30 Output Capacitor RMS

Ripple Current Transformer Construction

Parameters

Core/Bobbin E30/15/7 Margin Core and Bobbin Type Core Manuf. Generic Core Manufacturing Bobbin Manuf Generic Bobbin Manufacturing LP uHenries

1181 Primary Inductance

NP 71 Primary Winding

Number of Turns

NB 8.26 Bias Winding Number

of Turns

OD Actual mm 0.25 Primary Actual Wire

Diameter

Primary Current Density A/mm^2 6 Primary Winding

Current Density

VOR Volts 135.00 Reflected Output

Voltage

BW mm 17.30 Bobbin Physical

Winding Width

M mm 3.0 Safety Margin Width L 2.0 Number of Primary

Layers

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AE cm^2 0.60 Core Effective Cross Section Area

ALG nH/T^2 234 Gapped Core Effective Inductance

BM mTesla 207 Maximum Operating Flux Density

BP mTesla 267

Peak Flux Density BAC mTesla 73 AC Flux Density for Core Curves LG mm 0.28 Gap Length

LL uHenries 17.7

Estimated Transformer Primary Leakage Inductance

LSEC nHenries 20

Estimated Secondary Trace Inductance

Secondary Parameters

NSx

2.00

2.89 6.68 10.89 Secondary Number of

Turns

Rounded Down NSx

6 10 Rounded to Integer

Secondary Number of Turns

Rounded

Down Vox

Volts 3.27

10.62 18.17 Auxiliary Output Voltage

for Rounded to Integer NSx

Rounded Up NSx 3

7 11 Rounded to Next

Integer Secondary Number of Turns

Rounded Up Vox Volts 5.16

12.51 20.05 Auxiliary Output Voltage

for Rounded to Next Integer NSx

ODS Actual Range

0.64 - 1.03 0.51 - 0.81

0.25 - 0.40 0.20 - 0.32 Secondary Actual Wire Diameter Range

Comment: Wire

diameter is greater than recommended

maximum (0.40 mm) and may overheat.

Tip: Consider a parallel winding technique

(bifilar, trifilar), increase size of transformer (larger BW), reduce margin (M).

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9 Performance Data

All measurements performed at room temperature, 50 Hz input frequency.

9.1 Efficiency

Full power efficiency was measured as a function of line voltage and Figure 6 gives the resulting profile.

Efficiency as a function of output power was measured at 230V input, each rail load increased from zero to 100% load simultaneously in 10% load steps. Figure 7 shows the resulting efficiency profile.

Figure 7 - Efficiency Variation with Load

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9.2 No-load Input Power

Under zero output load conditions, the input power was measured at 400mW at 265V AC input.

9.3 Peak Power

The prototype was loaded to the specified peak power levels in Table 1 and the temperature of the TOP245P monitored. The 46W peak power level can easily be supplied in 25°C ambient conditions. Under peak power levels, the TOP245P temperature was measured at 86°C. Thus, a peak power of 46W in 50°C ambient is achievable and only thermal shutdown will limit the time the peak power can be delivered for. With the high operating efficiency of this design, peak power levels of above 50W can be achieved for a few seconds. 9.4 Regulation 9.4.1 Load

Figure 8 – Load Regulation, Room Temperature, 230V AC Input

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9.4.2 Line

Line regulation was measured at full continuous output power. The regulation, expressed as a percentage on nominal rail voltage, and as a function of line voltage is shown in

Figure 9 – Line Regulation, Room Temperature, Full Load.

9.5 Cross Regulation

Figure 10 gives the cross regulation results at 230V input.

Figure 10 - Cross Regulation

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10 Thermal Performance

At full continuous output power, the temperature of key components was monitored using

Figure 11 - Key Component Temperature Rise variation with Line Voltage

All key components are operating well within specified temperature ranges and this design would support operation in ambient levels up to 50°C.

11 Waveforms

11.1 Drain Voltage and Current, Normal Operation

Figure 12 - 195 V AC , Full Continuous Load Lower: I DRAIN , 0.5 A / div Upper: V DRAIN , 200 V, 2 μs /

div

Figure 13 - 265 VAC, Full Continuous Load Lower: I DRAIN , 0.5 A / div Upper: V DRAIN , 200 V / div

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11.2 Output Voltage Start-up Profile (Full Power)

Figure 14 -Start-up Profile, 230V AC Lower: 3V3, 1 V / div Upper: 5V, 2 V / div

Figure 15 - Start-up Profile, 230V AC

Lower: 3V3, 1 V / div Upper: 12V, 5 V / div

Figure 16 - Start-up Profile, 230V AC Lower: 3V3, 1 V / div Upper: 20V, 10 V / div

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11.3 Drain Voltage and Current Start-up Profile

Figure 17 - 195 V AC Input and Maximum Load. Lower: I DRAIN , 0.5 A / div.

Upper: V DRAIN , 200 V & 1 ms / div.

Figure 18 - 265 VAC Input and Maximum Load. Lower: I DRAIN

, 0.5 A / div.

Upper: V DRAIN , 200 V & 1 ms / div.

11.4 Load Transient Response

Figure 19 shows the load transient response of the 3V3 rail when subjected to a load change for 3A to 4A.

Figure 19 – Transient Response, 230 V AC , 3A to 4A Step load change on 3V3. Full Load. Lower – Current at 2A / div, Upper – AC coupled 3V3 voltage at 50mV / div