design reference of 3w ac-dc power supply 12v output

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2019.05.08-A/1 of 11 MORNSUN Guangzhou Science & Technology Co., Ltd. reserves the copyright and right of final interpretation

Design reference of 3W AC-DC power supply

12V output, input 85-305Vac,

SCM1702ASA & TTLS03-15B12T

Modification Date Version No. Reasons for Revision Model Application Field

2019.04.22 A0 First version SCM1702ASA Industrial control, Smart home ,Instruments

and apparatus

2019.05.08 A/1 Format and content optimization SCM1702ASA Industrial control, Smart home ,Instruments

and apparatus

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Contents

1. Overview ........................................................................................................................................................................................................... 3

2. Input & Output Specifications .................................................................................................................................................................. 3

3. Schematic Circuit Diagram .......................................................................................................................................................................... 4

4. Bill of material ............................................................................................................................................................................................ 5

5. Test Data.......................................................................................................................................................................................................... 6

5.1. Input Specifications ........................................................................................................................................................................ 6

5.1.1. No Load Power Consumption .................................................................................................................................................. 6

5.1.2. No Load Power Consumption .................................................................................................................................................. 6

5.2. Output Specifications ...................................................................................................................................................................... 6

5.2.1. Output Voltage&Output Current .......................................................................................................................................... 6

5.2.2. Linear Regulation&Load Regulation .................................................................................................................................. 7

5.2.3. Ripple & Noise ........................................................................................................................................................................ 7

5.2.4. Efficiency ................................................................................................................................................................................ 8

5.2.5. Capacitive Load ...................................................................................................................................................................... 9

5.3. Time series Test ................................................................................................................................................................................ 9

5.3.1. Start-up Time&Hold-up Time ................................................................................................................................................ 9

5.4. Protection specification .............................................................................................................................................................. 11

5.4.1. Over-current Protection(OCP) .......................................................................................................................................... 11

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1. Overview

This application is a reference design for an isolated AC-DC power supply based on 85-305VAC input and 12V/3W output. It is widely used

in Industrial control, power instrument and meters, smart home and other occasions that have strict requirements on volume, need to meet UL/CE

certification and low requirements on EMC. The circuit scheme adopts flyback circuit to attack, and the control core adopts SCM1702ASA chip

independently developed by our company. Its peripheral circuit is simple and has certain advantages in cost. In terms of performance, the chip has a

built-in 700V high-voltage start circuit that can start the controller in a wide input voltage range .After starting, the start circuit is closed to reduce the

loss of controller. At the same time, the output over-voltage protection circuit, FB pin fault protection, CS pin fault protection and over-temperature

protection are also integrated to meet the safety requirements.

2. Input & Output Specifications

Input Specifications

Item Operating Conditions Min Typ Max Unit

Voltage AC Input 85 -- 305 VAC

DC Input 70 -- 430 VDC

Input Current Vin=115VAC -- -- 0.12

A Vin=277VAC -- -- 0.06

No Load Power Consumption Vin=230V -- -- 0.25 W

Output Specifications


Output Voltage Input voltage range 11.40 12.00 12.60 V

Output Current Input voltage range -- -- 0.25 A

Output Power Input voltage range -- -- 3 W

Ripple & Noise 20MHz bandwidth -- 80 150 mVp-p

Linear Regulation Input voltage variation from low to high at full load -- ±1.5 -- %

Load Regulation 10%-100% load -- ±3.0 -- %

Efficiency nominal input voltage , full load -- 74 -- %

Short-circuit Protection Input voltage range Continuous, self-recovery

Short-circuit Protection 110%-500%Io, self-recovery

Hold-up Time Vin=115VAC -- 10 --

ms Vin=230VAC -- 40 --

Note: * Ripple and noise are measured by “parallel cable” method, please see AC-DC Converter Application Notes for specific operation.

Other Specifications


Operating Temperature -40 -- +85 ℃

Isolation Input --Output The test time is 1minute 3000 -- -- VDC

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3. Schematic Circuit Diagram

Figure 1. Schematic Circuit Diagram

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4. Bill of material

Device description Specification Quantity Position No.

Capacitor 106K/25V/1206/X7R 1.0 C6

Capacitor 271J/250V/0805/NP0 1.0 C1

Resistor 240KΩ 1/4W ±1% 1206 1.0 R2

Resistor 51Ω 1/4W ±1% 1206 1.0 R1

Capacitor 102K/2000V/1206/X7R 1.0 C2

Resistor 4.7KΩ 1/4W ±1% 1206 1.0 R4

Diode 1000V/1A eSGA 1.0 D2

Diode 200V/1.5A/SMA 1.0 D1

IC SCM1702ASA（MOTNSUN） 1.0 U1

Resistor 1KΩ 1/10W ±1% 0603 1.0 R5

Resistor 120Ω 1/8W ±1% 0805 1.0 R3

Resistor 8.2Ω 1/4W ±1% 1206 2.0 R10,R11

Resistor 4.7Ω 1/4W ±1% 1206 1.0 R12

Resistor 680KΩ 1/10W ±1% 0603 1.0 R8

Resistor 17.4KΩ 1/10W ±1% 0603 1.0 R7

Capacitor 104K/50V/0603/X7R 2.0 C3,C5

Resistor 68KΩ 1/10W ±1% 0603 1.0 R6

Resistor 100Ω 1/10W ±1% 0603 1.0 R13

Diode 600V/1A/35ns/1206 1.0 D3

Rectifier bridge 1000V/1.0A/ABS 1.0 D7

Transformer TTLS03-15B12T(MORNSUN) 1.0 T1

Electrical inductance 4.7uH/60mΩ/2.2A 1.0 L2

Safety capacitor Y1/102M/400VAC 1.0 CY1

Fuse wire 2A/300V 1.0 F1

Aluminum electrolytic capacitor 22uF/450V/Φ12.5*20 1.0 C7

Piezoresistor 561K/3500A/10D 1.0 MOV1

NTC Thermistor 10Ω/1A/5D 1.0 NTC1

Inductance 4.7mH/15Ω/0.1A 1.0 L1

Aluminum electrolytic capacitor 100uF/35V/Φ6.3*11 1.0 C9

Solid Capacitor 270uF/16V/Φ8*8 1.0 C8

Terminal 2*Φ1.0/Φ2.0-0.5/9.1 4.0 1,2,3,4

Note: Operating temperature and pressure value depend on the type of the device, and have a lot of to do with PCB layout. MORNSUN IC,

transformer TTLS03-15B12T working temperature; it is recommended to use surface -40-+85℃,TTLS03-15B12T isolation-pressure:3000VAC, the

leakage current is less than 5mA.

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5. Test Data

Test Item Test Result

1. Input Specifications

Input Current(230VAC/full load) 42.71mA

No Load Power Consumption(230VAC/no load) 0.14W

2. Output Specifications

Output Voltage 12VDC

Output Current 0.25A

Load Regulation 1.00%

Linear Regulation 0.67%

Ripple & Noise ＜70mV

Efficiency(230VAC/full load) 76.81%

Capacitive Load >2000uF

3. Time series

Start-up Time（230VAC） 204mS

Hold-up Time (230VAC) 142mS

4. Protection specification

Over-current Protection OK

Short-circuit Protection OK

5.1. Input Specifications

5.1.1. No Load Power Consumption

Operating Conditions: Input voltage variation from low to high at full load, measure input current.

Test Standard:115VAC＜0.12A。

Table 1. Input Current（full load）

Input Voltage 85VAC 230VAC 300VAC

Input Current(mA) 80.35 42.71 35.33

5.1.2. No Load Power Consumption

Operating Conditions: Input voltage variation from low to high at no load, measure input power.

Test Standard: <0.25W.

Table 2. No Load Power Consumption


Input Power(W) 0.08 0.14 0.14

5.2. Output Specifications

5.2.1. Output Voltage & Output Current

Test Item 85VAC 230VAC 300VAC

0% Io

Iin(mA) 3.27 1.64 1.39

Vin(V) 85.09 229.98 299.91

Vo1(V) 12.04 12.06 11.93

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Test Item 85VAC 230VAC 300VAC

□5% Io

■10% Io

Iin(mA) 12.67 6.77 5.56

Vin(V) 85.03 229.88 299.91

Io1(mA) 25 25 25

Vo1(V) 11.90 11.99 11.94

50% Io

Iin(mA) 44.07 22.14 18.98

Vin(V) 85.03 229.88 299.90

Io1(mA) 125 125 125

Vo1(V) 11.81 11.87 11.84

100% Io

Iin(mA) 76.54 39.34 32.03

Vin(V) 85.01 229.87 299.89

Io1(mA) 250 250 250

Vo1(V) 11.77 11.82 11.80

5.2.2. Linear Regulation & Load Regulation

Operating Conditions: Input voltage variation from low to high, Output load is 10%-100% load range.

Test Standard: Linear Regulation<±1.5%，Load Regulation<±3%。

Table 3. Linear Regulation & Load Regulation

Input Voltage Output Voltage(V)

Load Regulation (%) 10% Load Half Load Full load

85VAC 11.96 11.89 11.89 0.58

230VAC 12.04 11.92 11.92 1.00

300VAC 12.02 11.92 11.91 0.83

Linear Regulation (%) 0.67 0.34 0.25

5.2.3. Ripple & Noise

Operating Conditions: At room temperature, Input voltage variation from low to high, Output load is 10%-100% load range.

Test Standard: Ripple & Noise<150mV。

Table 4. Ripple & Noise Test Data

Input Voltage Ripple & Noise

Wave Table 10% Load Full load

85VAC 17.0mV 65.6mV Figure 2/Figure 3



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Figure 2. Ripple & Noise Wave Table(85VAC 10% Load) Figure 3. Ripple & Noise Wave Table(85VAC Full load)



5.2.4. Efficiency

Operating Conditions: At room temperature, Input voltage variation from low to high , Output load is within the entire load range.

Test Standard:230Vac>74%。

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Table 5. Efficiency

Input Voltage 10%Io Max 25%Io Max 50%Io Max 75%Io Max 100%Io Max Average Efficiency

85VAC 69.77% 77.73% 78.39% 78.47% 77.28% 76.32%

230VAC 59.21% 72.00% 73.94% 75.81% 76.81% 71.55%

300VAC 57.88% 66.26% 72.52% 74.40% 75.40% 69.29%

5.2.5. Capacitive Load

Operating Conditions: At room temperature, Input voltage variation from low to high, Output load is within the entire load range.

Test Standard: Capacitive Load>470uF.

Table 6. Capacitive Load Test Data

Capacitive Load

Input Voltage No Load Wave Table Full load Wave Table

85VAC ＞2000uF Figure 8 ＞2000uF Figure 9

230VAC ＞2000uF -- ＞2000uF --

300VAC ＞2000uF -- ＞2000uF --

Figure 8. No load with 2000uF Capacitive Load (85VAC)

Blue: VIN, Green: Vo

Figure 9. Full load with 2000uF Capacitive Load(85VAC)

Blue: VIN, Green: Vo

5.3. Time series Test

5.3.1. Start-up Time & Hold-up Time

Operating Conditions: Full load

Test Standard: Start-up Time＜2S， Hold-up Time＞10ms。

Table 7. Start-up Time/Hold-up Time Test Data

Test Item Input Voltage Data Wave Table

Start-up Time

85VAC 206ms Figure 10



Hold-up Time

85VAC 19.2ms Figure 13



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Figure 10. Power on waveform Blue: VIN ,Green: Vo(85VAC) Figure 13. Power off waveform Blue: VIN, Green: Vo(85VAC)

Figure 11. Power on waveform Blue: VIN, Green: Vo(230VAC) Figure 14. Power off waveform Blue: VIN, Green: Vo(230VAC)

Figure 12. Power on waveform Blue: VIN, Green: Vo(300VAC) Figure 15. Power off waveform Blue: VIN, Green: Vo(300VAC)

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5.4. Protection specification

5.4.1. Over-current Protection (OCP)

Operating Conditions: At the lowest, rated, and highest input voltage, the load is gradually increased until the output is turned off.

Test Standard: 110%-500%,self-recovery

Table 8. OCP Test Data


OCP output current(A) 0.410A 0.410A 0.395A

Recovery current(A) 0.370A 0.376A 0.356A

Figure 16. Protection specification Figure 17. self-recovery

If you have any suggestions or questions about this article, or consult other applications, please contact us [email protected] , we will give

you a detailed answer!

MORNSUN Guangzhou Science & Technology Co., Ltd.

Address: No. 5, Kehui St. 1, Kehui Development Center, Science Ave., Guangzhou Science City, Luogang District, Guangzhou, P. R. China

Tel: 86-20-38601850-8801 Fax: 86-20-38601272 E-mail: [email protected]

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design reference of 3w ac-dc power supply 12v output

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