STEVAL-ISA021V1

AN1735 Application note VIPer22A Single Output Reference Board 90 to 264 VAC input, 10W output Introduction This Application Note deals with an off-line wide range single output power supply using a VIPer22A off-line SMPS primary switcher manufactured by STMicroelectronics. The VIPer22A combines a dedicated current mode PWM controller with a high voltage Power MOSFET on the same silicon chip and its switching frequency is internally fixed at 60 kHz. The feedback path of the power supply includes an optocoupler for secondary regulation and galvanic isolation between primary and secondary sides. The output voltage is regulated at 12V with a maximum output current of 0.84A, resulting in a maximum output power of 10W. Product highlights July 2006 – Switch mode General Purpose Power Supply – Single-sided Board – 75% Typical Efficiency – Output Short Circuit Protection – Thermal Shutdown Protection – Complies with EN55022 Class B EMI specifications – Complies with Blue Angel standards Rev 2 1/15 www.st.com Contents AN1735 Contents 1 Summary description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 2 Board layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Test results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.1 Frequency ripple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2 Efficiency results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3 Load response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.4 Line and load regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.5 EMI emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3 Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4 Output current and voltage capability . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 5 Thermal considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6 Blue angel standard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7 Transformer specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 8 Component list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2/15 AN1735 1 Summary description Summary description Table 1 lists the main parameters of the converter while a prototype of the board is shown in Figure 1. Table 1. Operating conditions Parameter Input voltage range Input frequency range Limits 90 to 264 VAC 50/60 Hz Output Voltage V=12V Output current I=0.84A Output power 10W Efficiency 75% typical Line regulation ± 0% Load regulation ± 0.2% Output voltage ripple EMI Figure 1. 20m VPP EN55022 class B Board prototype 3/15 Summary description 1.1 4/15 AN1735 Board layout Figure 2. Board top legend (not to scale) Figure 3. Board bottom foil (not to scale) AN1735 Test results 2 Test results 2.1 Frequency ripple Figure 4 presents the line frequency ripple taken with an input voltage of 90 VAC. A 10mVPP amplitude is measured at the output. Figure 5 shows the switching ripple on the output at the full load of 0.84A. Figure 4. Line frequency ripple Figure 5. Switching frequency ripple 5/15 Test results 2.2 AN1735 Efficiency results Figure 6. Efficiency vs. POUT The typical efficiency of the board is about 75%. The efficiency measurements are taken at a nominal input voltage of 120 VAC. Figure 6 shows the efficiency measurements that are taken when the output power is varied from 1W to 10W. Figure 7 meanwhile shows the efficiency measurement taken when the input voltage is varied from 90 to 264 VAC at the maximum output power rating of 10W. The average measured efficiency is 75%. Figure 7. 2.3 Efficiency vs. VIN Load response At an input voltage of 120 VAC, the output load is stepped from 50% to 100% load (0.42A to 0.84A). The settling time is found to be 400µs and the dynamic regulation is 120mV or 1%. The resulting waveforms are shown in Figure 8. 6/15 AN1735 Test results Figure 8. 2.4 Transient load response Line and load regulation The output voltages are measured over the entire input voltage range, that is between 90 and 264 VAC. This gives the line regulation as shown in Figure 9. As can be seen from the graph, the output voltage remained at a constant +12V output. The line regulation therefore is 0%. Figure 9. Line regulation 7/15 Test results AN1735 The output voltage has also been measured in a range of loads, as shown in Figure 10 at a nominal input voltage of 120 VAC. The load regulation is approximately 0.125% when tested from 10% to 100% of full load on the output. Figure 10. Load regulation 2.5 EMI emissions Figure 11. EMI conducted emissions The results shown in Figure 11 indicate that the unit passes EN55022 Class B EMI conducted emission tests. 8/15 AN1735 3 Waveforms Waveforms Figure 12 shows the drain current (IDRAIN)and drain voltage (VDS) during normal operation at full load. The converter works in the Discontinuous mode as illustrated by the waveforms. Figure 12. VDS and drain current 4 Output current and voltage capability The output voltage and current can be set to a different value by changing components as shown in Table 2. Table 2. Changes in output voltage and current Vout T1 R8 R5 C9 C10 5.0V 2.0A CVP32-006 2.49KΩ 1% 2.49KΩ 1% 2x1000µF/25V 100µF/25V 12V 0.84A CVP32-001 13.3KΩ 1% 3.48KΩ 1% 1000µF/25V 100µF/25V 15V 0.67A CVP32-005 14.7KΩ 1% 2.94KΩ 1% 680µF/35V 100µF/35V 24V 0.42A CVP32-007 13.0KΩ 1% 1.50KΩ 1% 220µF/50V 100µF/50V 9/15 Thermal considerations 5 AN1735 Thermal considerations The VIPer22A is a single-sided reference board that uses a wide two-ounce copper pad area to act as a heat sink for the VIPer22ADIP. All other traces use one-ounce copper. At 65° C, the measured case temperature is 90° C, therefore making the junction temperature 123.7° C. 6 Blue angel standard The Blue Angel standard is a German certification for products and services that have environmentally friendly aspects. It requires that the power supply consumes less than 1W of power when in Standby mode. The total power consumption of this reference board is less than 1W when working in Standby Burst mode. Table 3 lists the input power consumption (PIN) values at different input voltages when measured with zero loads at the output. Table 3. Input power consumption in No-Load conditions Input voltage Input Wattage at No Load 115 VAC 200 mW 230 VAC 366 mW In order to keep the total input power to be less than 1W total, a minimum load of 40 mA is needed when using a 120 VAC input supply. Therefore, the reference board complies with the Blue Angel standard. 10/15 AN1735 7 Transformer specifications Transformer specifications Figure 13. Mechanical drawings of the transformer The transformer is designed and manufactured by Cramer Coil and Transformer Co. Table 4 lists the electrical characteristics of the transformer. Table 4. Electrical characteristics of the transformer Parameter Primary inductance Values 2.25mH ± 10% Primary leakage inductance 19.9µH typical HIPOT (N1, N3, N4 to N2) 5500VAC, 1Sec DCR (N1/N4) 2.87Ω typical DCR (N2) 0.07Ω typical DCR (N3) 1.26Ω typical Turns ratio (N1/N4:N2) 1:0.127 Turns ratio (N1/N4:N3) 1:0.167 When the VIPer22A (U1) is on, energy is stored in the primary winding of transformer (1-2), TX1. This energy is transferred to the auxiliary winding (3-4), and to the output (5-6) when the VIPer22A is off. The auxiliary winding provides the bias voltage for the VIPer22A at pin 4 (VDD). 11/15 Component list 8 AN1735 Component list Table 5. Component list Quantity 12/15 Reference Description 1 BR1 KBP210GDI 1 C1 0.047µF/250V boxcap 1 C2 22µF/400V electrolytic 1 C3 100pF 1kV ceramic 1 C4 22µF/25V electrolytic 1 C6 0.01µF/50V ceramic 1 C8 4.7nF/250V Y cap 1 C9 1500µF/25V electrolytic 1 C10 100µF/25V electrolytic 1 C11 0.01µF/50V ceramic 1 C12 10µF/400V electrolytic 1 D1 1N4148 1 D2 STMicroelectronics BYW98-200 1 F1 0.5A Fuse 2 J1, J2 Connectors 1 L1 2x30mH common-mode line choke 1 L2 Coilcraft 10µH inductor 1 R1 50Ω 5% 1W wire wound 1 R2 2KΩ 5% 1/2W 1 R4 68Ω 5% 1/4W 1 R5 3.48KΩ 1% 1/4W 1 R6 470Ω 5% 1/4W 1 R7 9.1kΩ 5% 1/4W 1 R8 13.3KΩ 1% 1/4W 1 T1 Cramer coil transformer CVP32-001 1 U1 STMicroelectronics VIPer22A 1 U2 H11A817A or LTV817 optocoupler 1 U3 STMicroelectronics TL431 1 W1, W2 Jumper wire AN1735 Component list Figure 14. Schematic diagram 13/15 Revision history 9 AN1735 Revision history Table 6. 14/15 Revision history Date Revision Changes Jul-2003 1 Initial release. 17-Jul-2006 2 Converted to new corporate template. Minor editing changes. AN1735 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. 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