STEVAL-ISA081V1 - STMicroelectronics
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1. Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 4 25 Demonstration board STEVAL ISA081V1 o ooccocccccoo eee 1 Input output connection of SMPS 0 0 nn 6 STEVAL ISA081V1 circuit schematic 0 0 0 00 eee 8 Transformer construction 0 0 0 ete eee 11 PCB layout from top side TOP BOT SMD BOT copper 000 eae 12 Efficiency at 120 VAC and 230 VAC vs output current 0 0000 15 Efficiency at full load 1 A vs input voltage 2 ee 16 Standby power vs input voltage 2 0 rn 17 12 V output load regulation 2 tenes 18 3 3 V output load regulation 20 0 eee eee 19 Output voltage at no load vs the input voltage level llle 19 EMI measurement regarding EN55022 Class 2 left peak detector right AVG detector citaciones a dea e 20 Thermal map of the board at 305 V AC on the input left bottom side right top side 21 Thermal map of the board at 85 V AC on the input left bottom side right top side 21 Doc ID 17812 Rev 2 ky UMO984 Main characteristics Main characteristics The main characteristics of the SMPS are listed below e Input Vin 85 305 Vrms frequency 45 66 Hz e Output 12 VDC 10 1 A at 3 3 V not loaded 3 3VDC 4 100 mA Maximum total output current of 1 A e Standby 120 mW at 230 VAC Short circuit protected e PCBtype and size FR4 Single si2. LJ UMO984 y User manual STEVAL ISA081V1 demonstration board based ona 12V 14A isolated flyback Introduction The purpose of this document is to provide information on the STEVAL ISA081V1 switched mode power supply SMPS demonstration board The STEVAL ISA081V1 is an isolated SMPS capable of delivering a 12 W output over a wide input voltage range It is designed for a mains application focused on providing a cost effective and space saving solution The STEVAL ISA081V1 SMPS generates 12 V nominal output voltage using primary regulation This board is based on VIPer 26LD a monolithic converter integrating a high voltage MOSFET and PWM controller in one package This document contains a fundamental technical description of the demonstration board schematic diagram PCB details and bill of materials as well as basic measurements load regulation efficiency standby behavior EMI and thermal behavior data The last section of this document contains short recommendations on how to set different output voltages in the range of 10 to 18 V and how to improve efficiency up to 86 Figure 1 Demonstration board STEVAL ISA081V1 7 DEMO BOARD ONLY FOR EVALUATION PURPOSE gt y u Lad 1 E lt x gt tu me a June 2012 Doc ID 17812 Rev 2 1 25 www st com Contents UMO984 Contents 1 Main characteristics 0ooooooooommmonmomnmmmmmm m m 5 2 Board conneclloli 22u rr e a A o a E 6
3. 3 Board description 22200 7 3 1 NIE 7 3 2 Description of main components ocococoo ee eee eee 9 3 2 1 The input section contains llis 9 3 2 2 The flyback converter consists of ooooocccoooooo eee eee 9 3 3 Transtormer tara aso Sees lina Adios at nita ais 10 3 4 LAYOUT socio artes A a a ea ee ma erac og eee 11 3 5 BOM stas sd de ed aen Doe Ie ta PR abad gus 13 4 Measurements i 4 a ic Ra E ERER ES 15 4 1 san M T 15 4 2 cg A PPM 17 4 3 Load regulation eee eh 18 4 4 P 20 4 5 Temperature 2 0 ee 21 5 Application recommendations sssssssss s 22 5 1 Output voltage operating range ococooccocccr ee 22 5 2 Improved efficiency 22 2 4 rise dei Rei READ TAL a PES 23 6 REVISION history iude icc a cac Gc UR da ER RO ACA a RR D d 24 2 25 Doc ID 17812 Rev 2 ky Document alternate name List of tables List of tables Table 1 Table 2 Table 3 Table 4 Table 5 Transformer WINANS seess sateni karta thaal eee 10 Bill f materials ss 0005 is en ad eal A oe AA AR RA 13 Settings and performance of demonstration board for different output voltages 22 Efficiency using a 60 V Schottky diode 0 0 ccc ee 23 Document revision history Doc ID 17812 Rev 2 3 25 List of figures UMO984 List of figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7
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5. current and therefore a low ESR capacitor is used The snubber circuit optional of D3 consists of C11 and R9 Thanks to the primary regulation no additional components are required A simple linear regulator to generate 3 3 V on the output can also be implemented The regulator IC2 plays also the role of a bleeder partly loading the output and keeping the output voltage below limits at no load In case IC2 is not assembled some type of bleeder either a Zener diode or resistor has to be applied in order to limit the maximum output voltage at no load Components C13 DB1 and D3 appear with a suffix A on the PCB This signifies that there is an assembled alternative package on the board The functionality of such a component is the same as the basic component and therefore these components are not indicated in the schematic visible in Figure 3 Transformer The transformer construction is designed in order to get good coupling between the auxiliary and secondary to reach applicable load regulation even when the primary regulation is used The transformer was developed in cooperation with WURTH ELEKTRONIK company and is available under order number 760871131 The transformer specifications are as follows Core shape E20 10 6 e e Core Al 150 nH e Primary to secondary isolation 4 kV AC E20 10 6 60 kHz voltage range 85 305 VAC Table 1 Transformer windings Wire Start Stop Number Wire Wire Inductan
6. input voltage 0 14 0 12 lt 0 1 0 08 Pin W 0 06 0 04 Stanby input power 0 021 Stand by input power without L78L33 0 50 100 150 200 250 300 Vin VAC The standby behavior of the board is displayed in Figure 8 The blue line is the standby input power of the fully assembled board The red line is the standby input power of the board without linear regulator L78L33 and with a 15 V Zener diode applied as a bleeder The typical input current of L78L33 is 3 5 mA which is approximately 40 mW of load present on the secondary side The standby input power was directly measured by power analyzer NORMA 4000 The output connection was kept open during the measurement ky Doc ID 17812 Rev 2 17 25 Measurements UMO984 4 3 Load regulation Figure 9 12 V output load regulation 14 12 Voyr 120 V 10 Vout 230 V VOUT 12v 8 V 6 4 2 0 4 0 000 0 200 0 400 0 600 0 800 1 000 lour mA The load regulation of the 12 V output is displayed in Figure 9 The output voltage at no output load is determined by the consumption of L78L33 If L78L33 is not implemented and no other bleeder Zener diode or resistor is used the output voltage rises The load regulation of the 3 3 V output is visible in Figure 10 18 25 Doc ID 17812 Rev 2 ky UMO984 Measurements Figure 10 3 3 V
7. output load regulation 3 5 3 Vout 2 5 2 Vout V 3 3 V output 4 0 5 O 0 0 02 0 04 0 06 0 08 0 1 0 12 lour A 3 3 V output The output voltage of the 3 3 V and 12 V output at no load depending on the input voltage is visible in Figure 11 Figure 11 Output voltage at no load vs the input voltage level 14 12 10 Vout 3 3 V Vout 12 V 8 Vour V 6 50 100 150 200 250 300 Vin VAC ky Doc ID 17812 Rev 2 19 25 Measurements UMO984 4 4 EMI The conductive EMI test of the demonstration board is displayed in Figure 12 The AVG detector is indicated on the left the peak detector measurement is indicated on the right Figure 12 EMI measurement regarding EN55022 Class 2 left peak detector right AVG detector Atten 20 dB Atten 20 dB Meas Uncal Stop 30 MHz VBW 30 kHz Sweep 881 3 ms 1515 pts Stop 30 MHz VBW 30 kHz Sweep 4 ks 1515 pts 20 25 Doc ID 17812 Rev 2 UMO984 Measurements 4 5 Temperature The thermal map at full load measured at 305 VAC and at 85 VAC is displayed in Figure 13 and Figure 14 The ambient temperature was 25 C Figure 13 Thermal map of the board at 305 V AC on the input
8. reserved STMicroelectronics group of companies Australia Belgium Brazil Canada China Czech Republic Finland France Germany Hong Kong India Israel Italy Japan Malaysia Malta Morocco Philippines Singapore Spain Sweden Switzerland United Kingdom United States of America www st com ky Doc ID 17812 Rev 2 25 25
9. 6 3 1 R4 3 9 Q 5 0 1 W 0805 4 1 R5 150kQ 1 0 1 W 0805 5 1 R6 43 kQ 1 0 1 W 0805 6 0 R7 Not assembled 7 1 R8 10 kQ 5 0 1 W 0805 8 0 R9 Not assembled 9 1 C1 100 nF 305 VAC X2 18x5x11RM15 EPCOS 10 1 C2 10 uF 450 V D12 5 x 20 RM5 11 1 C3 470 pF 200 V 1206 12 1 C4 10 uF 35V 105 C D5x11RM2 13 1 C5 2 2 nF 50 V 0805 14 1 C6 1nF 50V 0805 15 2 C7 C10 100 nF 50 V 0805 16 1 C8 470 uF 35 V low ESR D10 x 20 RM 5 17 1 C9 330 nF 50 V 0805 18 0 C11 Not assembled 19 1 C12 1nF 250 VAC 4 kV Y1 RM 12 20 0 C13 Not assembled 21 1 C13A 22uF 450V D16 x 20 RM 5 22 1 L1 CMC 2 x 10 mH UU9 8 RM 8x7 EPCOS 23 1 T1 EF20 1 41 mH EF20 W RTH ELEKTRONIK 24 0 DB1 Not assembled 25 1 DB1A 1A 800 V bridge SO DIL 26 1 D1 STTH1RO6A SMA STMicroelectronics 27 1 D2 1N4148 MINIMELF SOD80 28 0 D3 Not assembled 29 1 D3A STPS2H100U SMB STMicroelectronics 30 1 IC1 VIPER26LN SO16N STMicroelectronics 31 1 IC2 L78L33AC SO8N STMicroelectronics amp Doc ID 17812 Rev 2 13 25 Board description UMO984 Table 2 Bill of materials continued Index Quantity Ref Value generic part number Package class Manufacturer 32 1 J1 Screw terminal 2 pos RM 5 mm 33 1 J2 Screw terminal 3 pos RM 5 mm 14 25 Doc ID 17812 Rev 2 ky UMO984 Measurements 4 Measurements 4 1 Efficiency Figure 6 Efficiency at 120 VAC and 230 VAC vs output current 90 00 80 00 F
10. VIPer26 has to be in the range of 11 5 to 23 5 V which consequently limits the output voltage range using the same transformer There are theoretically several possible limiting factors caused by the transformer due primarily to the turns ratio The consequence of using a transformer designed for 10 V output for an 18 V output voltage level is a higher voltage stress on the primary side switch Thanks to the VIPer26 which has implemented an 800 V MOSFET there is still enough margin even at 18 V on the output The maximum drain source voltage measured at 305 VAC with 18 V set on the output was 700 V Doc ID 17812 Rev 2 ky UMO984 Application recommendations 5 2 Improved efficiency The measured efficiency is about 84 at full output load and 230 VAC This value can be increased by simply changing the output Schottky diode Please note that the original board contains an STPS3H100 3A 100 V Schottky diode This diode is universal applicable also up to 18 V output voltage If only 12 V output is required a 60 V Schottky diode can be used An STPS5L60 5 A 60 V Schottky diode in the SMC package was tested The result measured on one sample at 230 VAC is displayed in Table 4 Table 4 Efficiency using a 60 V Schottky diode D3 Vout V fullload loyr A full load Eff VD3 V at 305 VAC STPS3H100 11 80 1 00 84 1 56 STPS5L60 12 15 1 00 86 1 56 Doc ID 17812 Rev 2 23 25 Revision h
11. auxiliary voltage corresponds well with the secondary voltage and can be used for feedback regulation Mandatory components for proper operation of the VIPer26 are Vpp capacitor C4 and compensation network R8 C6 and C7 Diode D2 provides auxiliary voltage to C4 and the feedback voltage divider The voltage divider collecting feedback information for the FB pin is connected to the Vpp pin The total resistance of this voltage divider has to be designed with respect to the minimum charging current during startup and additional possible leakage currents Vpp capacitor The minimum charging current is 600 yA the maximum leakage current through the Vpp capacitor can be theoretically in the range of several tens of yA The total current through the voltage divider is therefore set to 150 yA to guarantee enough margin for the startup circuit Doc ID 17812 Rev 2 9 25 Board description UMO984 Note 3 3 10 25 Peak clamp D1 R2 R3 C3 This circuit absorbs energy from the voltage spike present after MOSFET turn off This spike is generated by leakage inductance of the transformer Alternatively a Transil based peak clamp can be used for instance PKC 136 The application of this device allows reducing standby consumption and it can also save some space on the board Secondary side D3 C8 C11 R9 C9 IC2 C10 The main secondary part is a rectifier consisting of D3 and C8 The C8 capacitor is stressed by a high level peak
12. ce Layer a B diameter Position pin pin of turns number material HH mm 1 3 1 96 2 0 2 Cu2l 1394 Primary 7 8 9 11 12 2 10 13 14 10 4 0 3 TeX 15 12V 1A 3 6 5 12 1 0 2 Cu2l 22 14 5 V aux Doc ID 17812 Rev 2 UMO984 Board description 3 4 Figure 4 Transformer construction 118 158 3 00 4 00 TERM NO s FOR REF ONLY 020 SQ 8 50 LOT CODE amp DATE CODE PART MUST INSERT FULLY TO SURFACE A IN RECOMMENDED GRID ale eg VN 12V 500mA T O gt le OO A 15V 100mA 12V 500mA T 3 9 RECOMMENDED P C PATTERN COMPONENT SIDE Layout The layout of the PCB is based on a single sided FR4 with 35 um thickness The size of the PCB is 32 x 90 mm The distance between the primary and secondary side is higher than 8 mm respecting the safety requirements for all standard applications The layout of the PCB is provided in Figure 5 The layout was designed with respect to the following rules to achieve stable operation good efficiency and reduce EMI noise e The power HF tracks are wide and short Transformer to IC1 Transformer to C13 C1 to C13 Transformer to C8 C8to D3 Transformer to D3 Peak clamp loop e The power and signal GND of VIPER26LD are separated and connected only in one point close to the source pins e The EMI filter has been placed far from the transformer to avoid possible crossta
13. ded 35 um 32x90mm e Isolation isolated 4 kV 8 mm e EMI according to EN55022 Class B Doc ID 17812 Rev 2 5 25 Board connection UMO984 2 6 25 Board connection The STEVAL ISA081V1 demonstration board is shown in Figure 2 below with input and output locations Figure 2 Input output connection of SMPS Output DC voltage GND 12V 3 3V DEMO BOARD ONLY z 12 FOR EVALUATION Ne 2 PURPOSE Input AC voltage 85 VAC 305 VAC Doc ID 17812 Rev 2 UMO984 Board description 3 Board description 3 1 Schematic A schematic diagram of the isolated flyback converter board prototype based on the VIPER26LD is provided in Figure 3 on page 8 ky Doc ID 17812 Rev 2 7 25 UMO984 Board description STEVAL ISA081V1 circuit schematic Figure 3 LA8BEEZONY cf QN9 AcL A E N XX AUR pes SEL DAN foren 3ulzz o ON Vv ASE 9 QNO GND ON VN doi En ON gu 99 WI as 8d doo Ko MZ 01 S IH g VOOHLHLLS Y ez 2X Ju 001 wr a Adsr AOS noos OLS adzz anjo 300181 eas Eo feo Av9z ASB I 9 cH NYYY Ye pm HU OL Xz H1 Doc ID 17812 Rev 2 8 25 UMO984 Board description 3 2 3 2 1 3 2 2 Note Description of main components The complete converter application consists of an i
14. ff 120 V 70 00 ome Eff 230 V 60 00 50 00 Eff 40 00 30 00 20 00 10 00 0 00 0 000 0 200 0 400 0 600 0 800 1 000 lout A Doc ID 17812 Rev 2 15 25 Measurements UMO984 Figure 7 Efficiency at full load 1 A vs input voltage 90 00 80 00 70 00 60 00 Efficiency 50 00 Eff 40 00 30 00 20 00 10 00 0 00 50 100 150 200 250 300 Vin VAC The output voltage efficiency depending on the output current of the 12 V output is displayed in Figure 6 The 3 3 V output was not loaded for this measurement Figure 7 shows the efficiency of the SMPS at full load applied on the 12 V output 1 A 3 3 V output not loaded depending on the different input voltages A drop of efficiency at low input voltage is mainly caused by an increase of the losses of the input inrush resistor and CMC The efficiency was calculated as the ratio between the output power and input power The input power was directly measured by power analyzer NORMA 4000 The output power was calculated as the product of the output current and output voltage The output voltage was measured on the output connector by multimeter KEITHLEY 2000 and the current was measured by multimeter FLUKE 189 16 25 Doc ID 17812 Rev 2 ky UMO984 Measurements 4 2 Standby Figure 8 Standby power vs
15. istory UMO984 6 24 25 Revision history Table 5 Document revision history Date Revision Changes 25 Nov 2010 1 Initial release 08 Jun 2012 2 Updated Figure 3 minor text corrections throughout document Doc ID 17812 Rev 2 UMO984 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
16. left bottom side right top side ax ee ees oe aca ee E EE ky Doc ID 17812 Rev 2 21 25 Application recommendations UMO984 5 5 1 22 25 Application recommendations Output voltage operating range The demonstration board STEVAL ISA081V1 was originally designed for output specification 12 V 1 A supplied from wide input range 85 to 305 VAC With minimal changes of components it is possible to set a different output voltage in the nominal output voltage range of 10 to 18 V keeping the output power capability The only changes are in the values of voltage divider R5 R6 The other components including the transformer remain the same Table 3 shows applicable values of the voltage divider for different nominal output voltages There is also visible an indicative value of output voltage at full and no load standby consumption and efficiency at full load measured on one sample Table 3 Settings and performance of demonstration board for different output voltages nominal value FS 69 R KS Teed full load atoad Vaux V no oad Ef C0 10 150 56 10 90 9 70 1 20 12 2 100 83 0 12 150 43 13 10 11 80 1 00 15 0 112 84 1 15 150 33 15 90 14 75 0 80 18 6 170 83 9 18 91 16 18 90 17 80 0 67 21 8 270 83 7 The major limitation regarding the setting of the output voltages is the VIPer26 supply range Vaux column and transformer design The supply voltage of
17. lk of EMI noise Doc ID 17812 Rev 2 11 25 Board description UMO984 Figure 5 PCB layout from top side TOP BOT SMD BOT copper DEMO BOARD ONLY ciz Ene 3 3V A FOR EVALUATION e PURPOSE e eo A e gt i 5 lt T id c4 ES a e e e 1 3 p e e gt o o i J1 bad WARNING COMPLIANT BSVAC 305VAC WARNING HIGH VOLTAGE ON BOARD a 03 R2 e a R3 o e o e o D cia e n L I Sow gt zx om AN DBI a me 2 275 e WARNING H DBIA lt e u a mol R4 R7 o Dr HA e C amp RB c9 o DIAZ o NI D Dg o R e On e cs D3e m D2 p e e C11 DSA R amp quam e e e e R e ee pi E 3 N if PE S wu M e e IE Y AN ve cas le 223 A ii DBT lt e a YD amp ss Ra VET EX e Dru e de C RB DIAZ e RS co DDG n R E Em ee cs D3e m p2F LY E E e e 11 3A R amp 12 25 Doc ID 17812 Rev 2 4 UMO984 Board description 3 5 BOM Table 2 Bill of materials Index Quantity Ref Value generic part number Package class Manufacturer 1 1 R1 5 1 0 2W Wirewound or 4 7 Q 2W Wirewound 2 2 R2 R3 51kQ 5 0 25 W 120
18. nput section and the flyback converter itself The input section contains Bridge diode rectifier DB1 The bridge diode rectifier is used to reduce the size of the input bulk capacitor Inrush current limiter R1 This component reduces the inrush current caused by the connection of the SMPS to the mains charging current of bulk capacitors or by surge pulses It is recommended to use a wirewound resistor to get higher immunity against current spikes EMI filter L1 C1 C2 C13 This basic EMI pi filter uses an X2 foil capacitor C1 bulk capacitors C2 C13 and a CMC inductor L1 Input bulk capacitors C2 C13 These capacitors store energy when the input AC voltage is low Their value respects the minimum input voltage and output power The maximum voltage of these capacitors is 450 V for this design because the maximum input voltage is specified up to 305 VAC If the maximum input voltage of the application is lower more often the value is 265 VAC 400 V capacitors can be used The flyback converter consists of VIPER26LD IC1 This device integrates a controller and high voltage power MOSFET in one package The controller works in current mode with a fixed frequency and in discontinuous mode even at the lowest input voltage Thanks to the built in error amplifier the VIPER26LD can directly sense the auxiliary voltage via a voltage divider R5 R6 Thanks to good coupling of the auxiliary and secondary windings the
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