AN2000 Application note

Transcription

1 Application note VIPower: VIPer53A dual output reference board 90 to 264 VAC input, 24W output Introduction This is an off-line wide range VIPer53 dual output reference board that is set up for secondary regulation through an optocoupler. This design is geared towards any general purpose off-line switch mode power supply needs. The total output power is 24W and is delivered through two output, +5V and +12V. The VIPer53 combines in the same package an enhanced current mode PWM controller with a high voltage MDMesh Power Mosfet. It is available in two packages: DIP-8 and PowerSO-10. Complete switch mode general purpose power supply Single-sided board Over 74% efficiency Output short circuit protection Thermal shutdown protection Meets EN55022 class B EMI specification Meets Blue Angel Operating conditions Parameter Input voltage range Input frequency range Limits 90 to 264Vac 47 to 63kHz Temperature range 0 to 80 C Output voltages V 1 = 5V; V 2 =12V Output power (peak) 24W Line regulation +/- 0% Load regulation Efficiency Output ripple voltage Safety EMI +/- 0.4% for 5V output 78% typical 1% ripple; less than 10mV if π filter is used at output Short circuit protection EN55022 class B August 2006 Rev 2 1/23

2 Contents Contents 1 General circuit description Transformer specification Line frequency ripple Efficiency Transient response Line regulation Load regulation Switching frequency ripple Components list Waveforms Blue Angel Output voltage and current capability T ovl function EMI PCB layout Revision history /23

3 List of figures List of figures Figure 1. Transformer specification Figure 2. Line frequency ripple (5V) Figure 3. Line frequency ripple (12V) Figure 4. Efficiency vs. V in Figure 5. Efficiency vs. P out Figure 6. Transient response Figure 7. Line regulation Figure 8. Schematic diagram Figure 9. Load regulation for 5V output Figure 10. Load regulation for 12V output Figure 11. Switching ripple for 5V output Figure 12. Switching ripple for 12V output Figure 13. Vds and drain current Figure 14. Short condition at 90Vac Figure 15. Short condition at 264Vac Figure 16. EMI result Figure 17. Board top legend (not in scale) Figure 18. Board bottom foil (not in scale) Figure 19. Board prototype (not in scale) /23

4 List of tables List of tables Table 1. Bill of material Table 2. Stand-by input power Table 3. Secondary side value components to obtain different output voltage Table 4. Revision history /23

5 General circuit description 1 General circuit description The reference design operates from 90 to 264Vac input with an output power peak of 24W through two output voltages of +5V and +12V. The AC input is rectified and filtered by the bridge BR1 and the bulk capacitor C2 to generate the high voltage DC bus applied to the primary winding of the transformer, T1. The switching frequency can be set to any value through the choice of R3 and C5 and here, it is set at 100kHz. Secondary regulation is provided by an optocoupler and TL431, U2 and U3 respectively. The optocoupler is connected in parallel with the compensation network on the COMP pin. Vdd voltage should be kept lower than the internal 15V reference and the auxiliary winding of the transformers have been designed to ensure that. The compensation resistor, R5, sets the dynamic behavior of the converter. It can be adjusted to provide the best compromise between stability and recovering time with fast load changes. It is possible to modify the output voltages by changing the transformer turns ratio and modifying the resistance values of R6 and R9 in the feedback loop. For output filtering, the components used are C8, C15, C16, and C19. An additional LC (PI) filter is added to the 5Vdc output, L2-C9 configuration, for further effective ripple and noise rejection. 5/23

6 Transformer specification 2 Transformer specification Figure 1. Transformer specification Primary Inductance 1.10mH ± 10% Primary Leakage Inductance 6.96µH typical When the VIPer53 (U4) is on, energy is stored in the primary winding of transformer (3-5), T1. This energy is transferred to the auxiliary winding (1-2), and to the +5V output (6,7-8,9), and the +12V output (10-11) when the VIPer53 is off. The auxiliary winding provides the bias voltage for the VIPer53 at pin 7 (V dd ). The transformer is designed and manufactured by Cramer Coil and Transformer Company, Inc. 6/23

7 Line frequency ripple 3 Line frequency ripple Figure 2. Line frequency ripple (5V) Figure 3. Line frequency ripple (12V) The line frequency ripple measurements are made at the input voltage of 120Vac. Here, the measured ripple is 10mVpp for +5V while it is 20mVpp for the +12V. 7/23

8 Efficiency 4 Efficiency Figure 4. Efficiency vs. V in Figure 5. Efficiency vs. P out Efficiency (%) 79.00% 78.50% 78.00% 77.50% 77.00% 76.50% 76.00% Efficiency Vin (Vac) Efficiency (%) 90.00% 80.00% 70.00% 60.00% 50.00% 40.00% 30.00% 20.00% Efficiency Pout (W) Efficiency is the ratio of the output power to the input power. Figure 4. shows the efficiency measurement vs. varying input voltage at maximum output power while Figure 5. shows efficiency vs. output power measurements, taken at the nominal line input of 120V AC. This reference board has an efficiency of 78% at 115V AC at full load for both outputs. 8/23

9 Transient response 5 Transient response Figure 6. Transient response The 5Vdc output current is stepped from 50% (1.2A) to 100% (2.4A) load, at a line input of 120Vac while the 12Vdc output is kept at the nominal value of 0.5A. The settling time is 400 µs. There is a 1.5% dynamic regulation or 75µV. This is shown in Figure 6. 9/23

10 Line regulation 6 Line regulation The change in the DC output voltage for a given change in the AC input voltage is referred to as line regulation. Both the 5V and the 12V outputs show a line regulation of 0% and 0.75% respectively. Figure 7. Line regulation Vout (V) V 12V Vin (Vac) 10/23

11 4.... Line regulation Figure 8. Schematic diagram All resistors are 1/4 W 5% unless specified. All capacitors are in uf and 50 V unless specified. C5 4.7nF C4 100uF 25V AC in L1 2 X 35mH C2 68uF R3 400V 3k CON2 85 to 264Vac C uF C uF 250V C uF 250V J V, 2A BRIDGE 3W Line FUSE 2A 5X20mm 250V R1 5ohms F2 4 3 BR1 2 1 C3 D5 4700pF 1.5KE220A 1kV D3 STTH1R06 STTA106 R2 22k 2W R12 1k 2W C14 100pF 1kV D2 STTH1R06 STTA106 R4 15 D1 1N4148 U4 1 Comp 2 Osc TOVL Vdd Source nc Source Drain VIPer53DIP R5 3.3k C7 470nF C uF 50V 0 0 Cramer Coil TR1 W1 0 C6 470nF R6 2.49k 1% 2 1 U3 TL431 ST 3 C uF 3 2 U2 LTV R9 2.49k 1% R7 1k R nF Y1 cap C10 12V rtn BYW C uF 25V C uF 25V 1A D4 C8 2700uF 16V C uF 16V C9 330uF 25V gnd 10uH L2 2.4A D6 STPS5L40 R10 22 C13 470pF J2 CON4 11/23

12 Load regulation 7 Load regulation The change in the DC output voltage for a given change in the output load is referred to as load regulation. The 5Vdc output stays within ± 0.4% while the 12Vdc output shows a ± 1% load regulation. Figure 9. Load regulation for 5V output Figure 10. Load regulation for 12V output Vout (V) Iout(5V) Iout (A) Vout (V) Iout (A) Iout (12V) 12/23

13 Switching frequency ripple 8 Switching frequency ripple Figure 11. Switching ripple for 5V output Figure 12. Switching ripple for 12V output The switching ripple for the +5V output measured is 10mVpp. The low ripple for the +5V output is obtained using the low pass LC (PI) filter configuration of L2 and C10. The waveform is taken at the input voltage of 120Vac. The switching ripple measured for the +12V output, meanwhile, is 100mVpp. 13/23

14 Components list 9 Components list Table 1. Bill of material Quantity Reference Description 1 BR1 600V, 1A bridge 1 C µF/250V boxcap 1 C2 68µF/400V electrolytic 1 C3 4.7nF 1kVceramic 1 C4 100µF/25V electrolytic 1 C5 4.7nF 50V ceramic 2 C6, C7 470nF 50V ceramic 1 C8, C µF/16V electrolytic 1 C9 330µF/25V electrolytic 1 C10 4.7nF/250V Y cap 2 C11, C µF 50V ceramic 1 C13 470pF 1kV ceramic 1 C14 100pF 1kV ceramic 2 C15, C µF/35V electrolytic 2 C17, C µF 275V boxcap 1 D1 1N D2, D3 STMicroelectronics STTH1R06 1 D4 STMicroelectronics BYW D5 STMicroelectronics 1.5KE220A 1 D6 STMicroelectronics STPS5L40 1 F1 2A Fuse 2 J1, J2 Connectors 1 L1 Panasonic 2x35mH common-mode line choke 1 L2 Coilcraft 2.2µH inductor 1 R1 4Ω 5% 3W Wire wound 1 R2 22kΩ 5% 2W 1 R3 3kΩ 5% 0.5W 1 R4 15Ω 5% 0.25W 1 R5 3.3kΩ 5% 0.25W 2 R6, R9 2.49kΩ 1% 0.25W 1 R7 1kΩ 5% 0.25W 1 R8 68Ω 5% 0.25W 14/23

15 Components list Table 1. Bill of material 1 R10 22Ω 5% 0.5W 1 R12 1kΩ 5% 2W 1 T1 Cramer Coil CVP U2 H11A817A or LTV817A optocoupler 1 U3 STMicroelectronics TL431 1 U4 STMicroelectronics VIPer53 2 W1, W2 Jumper wire 15/23

16 Waveforms 10 Waveforms Figure 13. shows the drain current and Vds at 230Vac full load. The converter is working in discontinuous mode as can be seen from the waveforms. Figure 13. Vds and drain current 16/23

17 Blue Angel 11 Blue Angel The reference board consumes less than 1W total power consumption when working in the burst mode during standby operation and therefore, meets Blue Angel. Table 2. below outlines the total power consumption measured on the reference board at different line voltages with zero loads at both the outputs. The output voltages remain regulated when operating in the burst mode condition. Table 2. Stand-by input power Input Voltage (Vac) Input Wattage at No Load (mw) /23

18 Output voltage and current capability 12 Output voltage and current capability Different output voltages and currents can be obtained by making the following changes: Table 3. Secondary side value components to obtain different output voltage Output Voltages T1 C15 and C16 D4 5V and 12V CVP µF/35V BYW V and 15V CVP µF/35V BYW V and 24V CVP µF/50V BYW /23

19 Tovl function 13 T ovl function Figure 14. Short condition at 90Vac Figure 15. Short condition at 264Vac There is a threshold of 4.35V set on the COMP pin of VIPer53. When V comp goes above this level, the capacitor connected to the T ovl pin will begin to charge. The internal MOSFET driver will be disabled and the device will stop switching when V tovl reaches 4V as shown in both figures 14 and 15. At this point, Vdd stops receiving any energy from the auxiliary winding, and therefore its voltage will drop until it reaches V ddoff and the device is reset. The Vdd capacitor will then be recharged for a new restart cycle. There will be an endless restart sequence if the overload or short circuit condition is maintained. 19/23

20 EMI 14 EMI The unit passes EN55022 Class B EMI as shown in Figure 16. Figure 16. EMI result 20/23

21 PCB layout 15 PCB layout Figure 17. Board top legend (not in scale) Figure 18. Board bottom foil (not in scale) Figure 19. Board prototype (not in scale) 21/23

22 Revision history 16 Revision history Table 4. Revision history Date Revision Changes Jul First issue 07-Aug New template - Component list value modified - Schematic diagram modified 22/23

23 Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries ( ST ) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST s terms and conditions of sale. Purchasers are solely responsible for the choice, selection and use of the ST products and services described herein, and ST assumes no liability whatsoever relating to the choice, selection or use of the ST products and services described herein. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. If any part of this document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such third party products or services or any intellectual property contained therein. UNLESS OTHERWISE SET FORTH IN ST S TERMS AND CONDITIONS OF SALE ST DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY WITH RESPECT TO THE USE AND/OR SALE OF ST PRODUCTS INCLUDING WITHOUT LIMITATION IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION), OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. UNLESS EXPRESSLY APPROVED IN WRITING BY AN AUTHORIZED ST REPRESENTATIVE, ST PRODUCTS ARE NOT RECOMMENDED, AUTHORIZED OR WARRANTED FOR USE IN MILITARY, AIR CRAFT, SPACE, LIFE SAVING, OR LIFE SUSTAINING APPLICATIONS, NOR IN PRODUCTS OR SYSTEMS WHERE FAILURE OR MALFUNCTION MAY RESULT IN PERSONAL INJURY, DEATH, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE. ST PRODUCTS WHICH ARE NOT SPECIFIED AS "AUTOMOTIVE GRADE" MAY ONLY BE USED IN AUTOMOTIVE APPLICATIONS AT USER S OWN RISK. Resale of ST products with provisions different from the statements and/or technical features set forth in this document shall immediately void any warranty granted by ST for the ST product or service described herein and shall not create or extend in any manner whatsoever, any liability of ST. ST and the ST logo are trademarks or registered trademarks of ST in various countries. Information in this document supersedes and replaces all information previously supplied. The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners STMicroelectronics - All rights reserved STMicroelectronics group of companies Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan - Malaysia - Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America 23/23