Switching Power Supply Technical Manual Chapter 1 Introduction To Power Supply 1.1 Introduction To Linear Power Supply ----------------------------------------- 1-1 1.2 Introduction To Switching Power Supply ----------------------------------- 1-2 1.3 Comparison Between Switching Power Supply And Linear Power Supply --------------------------------------------------------------------------------- 1-4 1.4 Application Of Switching Power Supply ------------------------------------- 1-5 1.
Switching Power Supply Technical Manual 2.20 Hi-Pot Test --------------------------------------------------------------------------- 2-11 2.21 Isolation Resistance -------------------------------------------------------------- 2-12 2.22 Power Good (P.G.)/(Pok) And Power Fail (P.F.) Signal------------------ 2-12 2.23 Alarm ---------------------------------------------------------------------------------- 2-12 2.
Switching Power Supply Technical Manual Chapter 7 Notes On Operation 7.1 Input Fuse ----------------------------------------------------------------------------- 7-1 7.2 Safety ----------------------------------------------------------------------------------- 7-1 7.3 Grounding ----------------------------------------------------------------------------- 7-1 7.4 Input And Output Wiring ---------------------------------------------------------- 7-2 7.
Preface To let our new employees and distribution partners have basic understanding about switching power supply, Mean Well published this “Switching Power Supply Technical Manual” based on our 22-year experiences in designing, manufacturing, and selling switching power supplies as well as the latest safety regulations and textbooks.
Chapter 1 Introduction To Power Supply Chapter 1 Introduction To Power Supply 1.1 Introduction To Linear Power Supply The topology of a conventional linear power supply, as shown figure 1.1, uses a low -frequency transformer comprising a core made of silicon steel sheet to convert AC mains to a desired voltage, and rectifies and filters the voltage to a DC level. Since general equipments require stable DC voltage, the rectified and filtered DC level should be regulated through a power regulator.
Switching Power Supply Technical Manual Figure 1.2 shows a typical linear power supply with the main features indicated: (A) transformer comprising a core made of silicon steel sheet, (B) the big input capacitor, and (C) the big transistor with its heat sink. Figure 1.2: Picture of a linear (serial) power supply 1.2 Introduction to Switching Power Supply (S.P.S.
Chapter 1 Introduction To Power Supply Small volume Light weight Generate noise Use for high frequency situation, small volume DC Output AC Input Tr Still has good efficiency at high voltage and low capacitance Transistors operate in switching-mode The efficiency is high,but will induce high A frequency noise PC + PWM Control Circuit Figure 1.
Switching Power Supply Technical Manual (g) Feedback Control: It regulates the output voltage to a steady level to respond to variation of loads and AC input voltage. (h) Protection Circuit: When in abnormal situations, the S.P.S. will shut down or go into other protection modes by activating protection circuits. The protection circuits consist of over voltage, over temperature and over current (overload) protections, and etc. For further explanation, refer to section 1.5 1.
Chapter 1 Introduction To Power Supply 1.4 Applications Of Switching Power Supply Switching power supplies have gradually taken the place of linear power supplies and been widely used in every kind of electronic equipments such as the source for module application, driving circuit, uninterruptible power supply (UPS), and battery charger, etc..
Switching Power Supply Technical Manual If the input side needs to be isolated from the output side, the above 3 basic converters would be inappropriate. Instead, the converter topologies, which are Forward, Flyback, Half-bridge, Push-pull, or Full-bridge, derived from the 3 basic ones would be the right ones to use.
Chapter 1 Introduction To Power Supply (c) Buck-Boost Regulator When the switch (MOSFET) is ON, the energy is stored in L1. When the switch is OFF, the energy stored in L1 is transferred to the load (RL) through L1 and D1. D1 ON MOSFET C1 L1 Vcc ton T Vo ton 1 T V c c OFF RL + D>0.5 D<0.5 Vo Vcc V o V c c Figure 1.
Switching Power Supply Technical Manual (b) Forward Converter When the switch (MOSFET) is ON, the energy is transferred to the load (RL) and stored in L1 through D1 and transformer. When the switch is OFF, the energy stored in L1 is transferred to the load through D2. The topology of using two MOSFETs (Double-end) can reduce the voltage stress on the switches. D OFF C1 ON S D2 G L1 D1 T1 P1 RL S1 Vcc G D ON POWER SWITCH S MOSFET Figure 1.
Chapter 1 Introduction To Power Supply (d) Half-Bridge Converter When switch 1 (MOSFET 1) is ON and switch 2 is OFF, the energy is transferred to the load (RL) through transformer, C2, and D1; when switch 2 is ON and switch 1 is OFF, the energy is transferred to the load through transformer, C1, and D2. The Asymmetric Half-Bridge Converter (commonly used in S.P.S. with PFC) derived from it can achieve higher efficiency.
Switching Power Supply Technical Manual 1.6 The Characteristics and Applications of Hard Switching Converters in S.P.S. Existing varieties of topology in S.P.S. can be used to meet all types of demand. In theory, S.P.S. only has conduction loss and is without switching loss since it operates only at the ON/OFF period of the switch (MOSFET).
Chapter 1 Introduction To Power Supply 1. Simple driving circuit 2. Complicated topology compared to flyback Forward 3. Voltage rating of switch must be 1.5~2 times higher than max input voltage 4. Application of higher power rating 1. Simpler driving circuit due to common negative ends of two switches Push-Pul 2. Voltage rating of switch must be 1.5~2 times higher than max input l voltage 3. Similar topology to double-end Forward converter HalfBridge FullBridge 1. Complicated driving circuit 2.
Switching Power Supply Technical Manual 1. More components 1. Design of high efficiency and 2. Complicated driving circuit free-air convection 3. Requiring collocation with 2. Suitable for application of middle or complicated circuit for auxiliary high power rating ZVS/ZCS switch 3. Complicated control circuit; low 4. High efficiency; low switching loss reliability 4. Strict limitation on selections of active components 1.8 The Characteristics and Applications of High-Efficiency Secondary Topologies in S.
Chapter 1 Introduction To Power Supply 1.
Switching Power Supply Technical Manual 1.10 Example of a Typical Switching Power Supply Figure 1.13 shows a typical Forward circuit with PFC and PWM.
Chapter 1 Introduction To Power Supply (3) EMI filter – As show in block (A) of figure 1.13 (excluding ZNR1, the surge absorber), this module of EMI filter is commonly used at the input side of our products to filter out noises interference. Basically, it consists of three types of components, which are X capacitor, Y capacitor, and common-mode choke. The functionality of each component in block (A) is as follows: C1 and C2 (X capacitor) suppress differential-mode noise.
Switching Power Supply Technical Manual (11) Snubber Circuit: RA and CA, located in primary side of T1 and secondary rectifiers (D10), are mainly to reduce the high-frequency spikes and oscillation coming from switching transitions of switches or rectifiers, such as Q2 and D10. EMI performance and decreases withstand voltage on components.
Chapter 2 Explanation of Switching Power Supply Specification Chapter 2 Explanation of Switching Power Supply Specification 2.1 Input Voltage / Frequency S.P.S. has been used in various field applications all over the world. Depending on type of product, input source of either alternating current (AC) or direct current (DC) is acceptable.
Switching Power Supply Technical Manual (1) If input voltage is of DC or square wave, its maximum value should be equal to 1.4 (√2) times of the peak value of sine wave. For example, input voltage of 85~264VAC can be replaced with DC voltage of 120~370V. (2) Input source of DC or square wave is not acceptable for S.P.S. with function of input voltage auto-selection. (3) Input Frequency: The frequency of AC mains for S.P.S. is generally 50Hz or 60Hz.
C h a p t eE r x2p l a n a t i o n o f S w i t c h i n g P o w e r S u p p l y S p Compared to the input current in steady state, the inrush current could be several to tens of times higher. Be aware that application with multiple S.P.S. leads to accumulate inrush current. In this case, the ability of input wiring, external fuses, and switches to withstand transient current should be taken into consideration. Inrush Current Limiting Circuit C1 C2 FUSE C3 Bulk Capacitor Figure 2.
Switching Power Supply Technical Manual 2.5 Leakage Current Leakage current is the current flowing from the protective earth (PE) conductor, such as metal enclosure, of equipments to frame ground (FG). Due to EMI requirements in S.P.S., there are Y capacitors (C2 and C3 in Figure 2.2) connected in between AC L/N and PE conductor. A low current will flow through the Y-caps to FG. In reality, leakage current should be regulated to comply with safety standards.
Chapter 2 Explanation of Switching Power Supply Specification Some channels of multi-output models would be allowed to deliver at the maximum value of output current range, but the total output power should not exceed rated value. For example, take D-60A with outputs of 5V@6A & 12V@4A, and maximum output power of 58W. If we use 5V output at 6A, and 12V output at 4A, the total output power would be 78W which exceeds the maximum value.
Switching Power Supply Technical Manual o Pr be t is ip l th s es an 10 mm Probe ground + Terminal 0.1uF Testing terminal Figure 2.5: Configurations of R&N measurement 2.9 Load Regulation The variation in output voltage, corresponding to change in output load between minimum value and full value, is called load regulation. In general, high output current would lead to slight voltage drop at the output terminal.
Chapter 2 Explanation of Switching Power Supply Specification 2.12 Set Up, Rise, Hold Up Time Set up time (ton): The time from power on to 90% of rated output voltage, or from AC powered on to operation of S.P.S. Rise time (tr): The time it takes for output voltage to rise from 10% to 90% of rated value. It is usually within 50ms. Longer period than that might lead to malfunction of system. Hold up time (th): The time from power off to 90% of rated output voltage.
Switching Power Supply Technical Manual 2.14 Transient Recovery Time The time required for output voltage to settle within specified tolerance value while output load is in drastic change. The general requirement is 500us at most. di/dt Load Current Output Voltage Tr Tr Output Voltage Tolerance Tr:Transient Recovery Time Figure 2.8: transient recovery time 2.15 Temperature Coefficient It stands for the variation in output voltage due to change in ambient temperature. The unit is in terms of %/℃.
Chapter 2 Explanation of Switching Power Supply Specification (3) Over Power Limiting Output power remains constant. As output load increases, output voltage decreases in proportion (curve (c) in figure 2.9). (4) Hiccup Current Limiting Output voltage and current keep pulsing ON and OFF repeatedly when protection is activated. The unit automatically recovers when fault condition is cleared. (5) Shut Off Output voltage and current are cut off when output load reaches protection range.
Switching Power Supply Technical Manual Protection Types: (1) Shut Off S.P.S. restarts by manual AC re-power on of after fault condition is removed or over. (2) Hiccup Voltage Limiting Output voltage keeps pulsing ON and OFF repeatedly when protection is activated. The unit automatically recovers when fault condition is cleared Basically, there are two kinds of O.V.P. detection: (1) Secondary detection circuit feeds back signal to disable PWM IC from operation.
Chapter 2 Explanation of Switching Power Supply Specification Figure 2.10: Instruments for vibration test 2.20 Hi-Pot Test (1) Hi-pot testing is made on behalf of safety regulation, and is one way to verify the effectiveness of primary-to-secondary isolation of S.P.S., so as to confirm that the SPS can withstand high voltage without breakdown. The test voltage should be gradually increased from 0V to preset level and remains at preset level for 60 seconds.
Switching Power Supply Technical Manual 2.21 Isolation Resistance It is to determine the dielectric strength of insulation materials by applying DC voltage. The unit is expressed in MΩ (mega-ohms). The tests are to verify the isolation resistance of transformers, PCB, and etc. The criteria of isolation resistance are not defined in IEC60950-1. 2.22 Power Good (P.G.)/ (Pok) and Power Fail (P.F.) Signal When S.P.S. is powered on or off., PG/Pok, or PF signals are sent out for status monitoring. P.G.
Chapter 2 Explanation of Switching Power Supply Specification (3) Alarm functions could malfunction when the total output load is below 10% of rated current in parallel application of S.P.S. 2.24 Auxiliary Power External power source may be required for S.P.S. with remote control or alarm function for status monitoring. For convenience of application, the power source is designed into the S.P.S.
Chapter 3 Introduction To Safety Chapter 3 Introduction To Safety 3.1 Introduction to Safety To insure the safety of life and property, safety inspection of products becomes increasingly more important. UL/CSA/TUV safety standards are used to verify that the products meet safety requirements. Soundness of design, component selection, and overall quality are also checked at the same time.
Switching Power Supply Technical Manual 3.3 Safety Marks found on MW products (1) (2) Considered as a component to be installed in a complete system. The NO. E127738 is equivalent to compliance of UL1012. File Considered as a component to be installed in a complete system. This mark represents universal certification. Both UL/CSA standards are met. (3) Categorized as final product. This mark represents universal certification. Both UL/CSA standards are met.
Chapter 3 Introduction To Safety (3) Safety-Extra-Low-Voltage (SELV) This regulation applies to the secondary circuitry. The circuit should be designed to guarantee that under normal operating conditions, the voltage between any two touchable points should be less than 42.4Vpeak or 60Vdc. For classⅠ equipment, it refers to “between any touchable point and the ground.
Switching Power Supply Technical Manual Clearance Distance Creepage Distance Figure 3.1: Clearance Distance and Creepage Distance 3.5 Category of Safety Tests (Refer to IEC-60950-1, including all S.P.S. related tests) (1) Input Test The steady state input current of the equipment shall not exceed the rated current by more than 10% under normal load. (2) Marking a. Rated voltage(s) or rated voltage range(s), in volts. (Should add on the ” ” symbol for DC input). b.
Chapter 3 Introduction To Safety (4) Humidity Test For insulating materials that their insulating characteristics may vary under different humidity, the humidity test should be made. Humidity test is carried out for 48 hours in a cabinet or room containing air with a relative humidity of 91%~95%. The temperature of the air, at all places where samples can be located, is maintained within 1℃ between 20℃ and 30℃ such that condensation does not occur.
Switching Power Supply Technical Manual Table 3.
Chapter 3 Introduction To Safety (9) Creepage Distance Measurement Working voltage measurement in conjunction with insulation level can be used to find out what is the minimum creepage distance based on Table 3.3.
Switching Power Supply Technical Manual Example: If the input voltage is 240VAC and the voltage between the primary circuit and secondary circuit is 275Vrms, 600Vpeak, what are the minimum creepage and clearance distances under the situation of Pollution Degree 2 and Insulation Material Group III by using Linear Interpolation Method? (Please refer to Tables 3.1, 3.2, & 3.3). Ans: Creepage：2.5 + (275 - 250)/(300 - 250) * 0.7 =2.5 + 0.35 = 2.85 So, it is 2.9 mm for Basic Insulation and 2.9 mm * 2 = 5.
Chapter 3 Introduction To Safety (11) Stability Test The test unit shall remain balanced when tilted to an angle of 10° from its upright position. This is to make sure that this condition will pose no danger to the user or repair personnel. (12) Impact Test A product consisting of complete enclosure should pass the impact test. A solid smooth steel ball, approximately 50mm in diameter and with a mass of 500g±25g, is permitted to fall freely from rest through a vertical distance of 1.3 meter.
Switching Power Supply Technical Manual (13) Drop Test For hand-held and direct plug-in equipments, a sample of the complete equipment is subjected to three impacts resulting from being dropped onto a horizontal hardwood surface. The drop height should be 1 meter and the sample can’t induce any danger or show insufficient insulation after testing. However, it is not required that the sample can still function properly.
Chapter 3 Introduction To Safety Table 3.5 - Maximum current Type of Equipment Maximum Touch Current ClassⅠ Hand-held 0.75mA ClassⅠ Others 3.5mA ClassⅡ All 0.25mA (18) Electric Strength Test The purpose is to make sure that the insulation materials in the equipment have enough electric strength. Two portions of the sample will be tested: isolating transformer and switching power supply.
Switching Power Supply Technical Manual 3.6 Comparison between regulations Category Creepage/ clearance distances Working voltage: Max.250Vrms Electric strength test Isolation resistance IEC60950-1 IEC60601-1 IEC60065 EN60335-1 Basic insulation 2.5mm/2mm 4mm/2.5mm 2.5mm/2mm 2.
Chapter 3 Introduction To Safety 3.7 Reference data (1) EU website：Search for CE directives. http://europa.eu.int/comm/enterprise/newapproach/standardization/harmstds/reflist.html (2) UL website：Search for UL certificate and Introduction to regulations. http://www.ul.com/ (3) TUV website：Search for TUV certificate and newsletter. http://www.twn.tuv.com/ (4) CSA website：Search for CSA certificate and Introduction to regulations. http://directories.csa-international.
Chapter 4 Introduction To EMC Chapter 4 Introduction To EMC 4.1 Introduction of EMC EMC (Electromagnetic Compatibility) is divided into two sections, which are EMI (Electromagnetic Interference) and EMS (Electromagnetic Susceptibility). By definition, EMI refers to emissions of electromagnetic energy from a device or system that interferes with the normal operation of another device or system.
Switching Power Supply Technical Manual (2) The most popular EMI regulations are CISPR22/EN55022, and the limits are listed on the Table 4.1. Table 4.1: Limit for Conducted Emission of class B equipments Limit in dB (uV) Range of frequency MHz Q.P AVG 0.15-0.5 66-56 56-46 0.5-5 56 46 5-30 60 50 Note: The frequency band in between 0.15MHz and 0.5MHz, the limit decreases linearly with respect to the logarithm value (Figure 4.1). Figure 4.
Chapter 4 Introduction To EMC Figure 4.2： CISPR22 / EN55022 Class B (Radiation Limit) 4.3 Definition of Harmonic Current and Related Regulations (1) For a traditional AC/DC converter, there is a bridge rectifier and bulk capacitors which charges/discharges in a very short period of time. Hence, a high current pulse is introduced at AC input line and generates harmonic current noises through the power line.
Switching Power Supply Technical Manual Figure 4.5: Equipment set-up for harmonic testing (2) Since, harmonic current pollution on power distribution network is becoming more and more serious. CENELEC announced the latest standard EN61000-3-2:2000 to regulate harmonic current. All members of the European Union began to execute the regulation on July 1st, 2001, and official enforcement of this regulation commences after Jan 1st, 2004.
Chapter 4 Introduction To EMC (3) If MW power supply is not used in Class D equipments, than any products with input power <150W are able to meet Class A Limit (Table 4.3) without the PFC circuit. For input power >150W, power supply will need PFC circuit in order meet Class A and Class D limits. Table 4.3：Limits for Class A equipment Harmonic order n Maximum permissible harmonic current (A) Odd harmonics 3 5 7 9 11 13 15 ≦ n ≦39 2.30 1.14 0.77 0.40 0.33 0.21 0.15*15/n Even harmonics 2 4 6 8 ≦ n ≦40 1.
Switching Power Supply Technical Manual 4.4 Explanation of EMS EMS (Electro-Magnetic Susceptibility) refers to the correct operation of electrical equipments in the presence of electromagnetic disturbances. The most common electromagnetic interferences are listed on the following table.
Chapter 4 Introduction To EMC Product Category EMI Standard EMS Standard Industrial Scientific and Medical (ISM) equipment CISPR11 (EN55011) EN61000-6-2/EN60601-1-2 Information Technology equipment CISPR22 (EN55022) CISPR24 (EN55024) Household appliances, electric tools and similar apparatus CISPR14-1 (EN55014-1) CISPR14-2 (EN55014-2) Power supply DC output (stand alone) TV/Audio Broadcasting Receiver & its Auxiliary CISPR22 (EN55022) CISPR13 (EN55013) EN61204-3 CISPR20 (EN55020) 4.
Switching Power Supply Technical Manual (3) EMS Standard (EN61000-6-2)-Heavy industry A numbers of MW products are certified according to Heavy industry standard, due to operating environment and customer application requirement. The test procedures are the same as ITE (EN55024); however, the test levels are different (see below).
Chapter 4 Introduction To EMC 4.7 EMC Tests: Procedure And System Allocation Refer to CISPR22, IEC61000-4 regulation, and Meanwell EMC reports for detailed information. (1) Conduction Emission 1. If the power cord can not be shrunk to a suitable length, so that it is 40cm above the metal plane. The excess wires should be bundled to a length of 30~40cm. 2. Simulated resistive network should be attached to the ground plane before connection to the EUT. 3.
Switching Power Supply Technical Manual (2) Radiation Emission 1. If the power cord can not be shrunk to a suitable length, so that it is 40cm above the metal plane. The excess wires should be bundled to a length of 30~40cm. 2. The power box should be installed on a metal plane and parallel to ground. The simulated resistive network should be placed under the horizontal metal plane. 3. The power cord should be laid flatly on the ground before connecting to the power outlet.
Chapter 4 Introduction To EMC (3) Voltage Fluctuations and Flicker 1. Set the output of Power Analyzer to 230V/50Hz 2. Testing periods are 1) Short time Tp=10min and 2) Long time Tp=2hrs 3. Power Analyzer will collect all the measured data and reports the result.
Switching Power Supply Technical Manual (4) ESD (Electrostatic Discharge) Test Procedure Apply ESD to EUT’s conduction and coupling surface. 1. The EUT shall to subject to 200 contact discharge. 100 times each for negative and positive discharge. 2. Pick four test points. 3. Center of EUT and side of HCP should be subjected to contact discharge of 50 times. 4. Other 3 points should be tested 50 times each. 5.
Chapter 4 Introduction To EMC (5) RS (Radiated Susceptibility) Setup 1. Test shall be conducted in a special chamber lined with radiation absorbing plates. 2. Antenna is set at 1m above ground. 3. Antenna is placed at 3m from EUT. 4. EUT placed at 80cm above ground on a non-conducting surface. Test procedure 1. A signal from the signal generator is sent through an amplifier to magnify it to the required level and then projected from the antenna. The EUT is subject to this radiated interference. 2.
Switching Power Supply Technical Manual (6) EFT (Electrical Fast Transient) Setup This test also needs to be executed on the reference ground plane and we only have to connect our sample to the equipment and select the test program. Test procedure The testing equipment will send out a 5 KHz continuous waveform for 15ms and we have to check whether it could cause a fault during power supply operation.
Chapter 4 Introduction To EMC (7) Surge Setup 1. This test should be executed on the reference ground plane. 2. EUT should be place 80cm above ground on a non-conducting table. Test procedure 1. The purpose of this test is to make sure that the power supply will not fail when a simulated surge is inserted through the AC source. 2. Connect AC source to the test sample and select the test program.
Switching Power Supply Technical Manual (8) CS (Conducted Susceptibility) Test signal send through AM modulator (1 kHz, 80%) Setup 1. This test also should be executed on the reference ground plane and the power supply will be put on a non-conductive object which is 10cm away from the ground. 2. The power cord should be made a short as possible.
Chapter 4 Introduction To EMC (9) MF（Power-Frequency Magnetic Field） Setup This test is executed on a reference ground plane and the power supply should be located 10cm above this plane. Test procedure 1. Test equipment will send out a certain current flowing through the antenna surrounding the power supply. We have to check whether a fault condition occurs to the power supply due to the magnetic field induced by the current. 2. Place sample within the antenna and proceed with the test. 3.
Switching Power Supply Technical Manual (10) DIP (Voltage Dip / Interruption) Setup This test should be executed on a reference ground plane. We only have to connect the power supply to the test system and the pre-set program will automatically execute the test. Test procedure The purpose of this test is to change the power quality supplied to the sample unit and check whether it would fail under this interference. 1. Check influence of voltage dip/interruption on test sample. 2. Dip > 95% → 0.
Chapter 5 Introduction To CE Chapter 5 Introduction To CE 5.1 Introduction to CE Marking The European Union introduced the “CE mark” in an effort bring awareness to the need for health, safety, and environmental protection. Through CE marking, consumers will know which products are designed with their best interest in mind. Generally speaking, all products with safety concerns must have the CE mark in order to be exported to countries in the EU.
5.3 CE Compliance The “CE Mark” is not issued by any particular regulatory agency. Manufacturers can declare conformity by fulfilling directives related to their field. For instance, the self declaration certificate of an electronics manufacturer will be composed of a list of directives that were satisfied. This is the only prerequisite for showing the CE mark.
Chapter 5 Introduction To CE EMC test method and setup: I/P S.P.S. Resistors Load 360mm steel 360mm t=1mm Metal plane Figure 5.1: Standard setup for EMC test The “CE marking” is a permit for products to enter the European market. Once our company signs the CE Declaration for a certain product, this means that the product meets the requirements of LVD and EMC directives.
Chapter 6 Reliability Chapter 6 Reliability 6.1 Curve of Lifetime and Failure Rate High reliability of switching power supply has been proved from its extensive use in household appliance and industrial equipment. The industrial sector holds SPS in high regards. Figure 6.1 is a typical curve of product lifetime and failure rate (Bath-Tub Curve). Fatigue Failure Period Initial Failure Period Random Failure Period High Failure Rate Low Operation Time Figure 6.
Switching Power Supply Technical Manual (2) Random Failure Period The stability of the S.P.S is related to its reliability (MTBF: Mean Time between Failure) and generally speaking, the failure rate is very low. But, the random failure rate has a lot to do with user’s installation and operating conditions (ambient temperature, derating, ventilation, and vibration). (3) Fatigue Failure Period After the “random failure period”, S.P.
Chapter 6 Reliability Khrs Lifetime Long Short 0 C Low Ambient Temperature High Figure 6.2: Lifetime of the power supply versus ambient temperature (3) Estimation of Electrolytic Capacitor’s Lifetime (Based on output capacitors). Ln: Lo*2(Tm-Tn)/10 *2 r[1-(InIm) 2 ] Ln: expected lifetime of the electrolytic capacitor. Lo: lifetime of the electrolytic capacitor working at maximum temperature and maximum ripple current. Tm: accepted maximum ambient temperature of the electrolytic capacitor.
Switching Power Supply Technical Manual Ambient Temperature Ambient Temperature Ambient Temperature 40℃～45℃ Once per three years 35℃～40℃ Once per four years 30℃～35℃ Once per five years The data above will vary depending on component grade used for the S.P.S. Please contact your local supplier for more information about the maintenance and repair services. 6.4 Load Capacity and Ambient Temperature Internal temperature of the S.P.S. will vary depending on output load condition and efficiency.
Chapter 6 Reliability Figure 6.4 Picture of ambient tester (chamber) (2) Free Air Convection Models (SP-100-24) TC TC 100 100 90 90 80 80 TCAP TCAP 70 TA1 70 TPC 60 TPC 60 TA1 50 50 40 40 30 TA 30 TA 20 20 40 60 Ta=25°C 80 100 20 LOAD(%) 20 40 60 80 100 LOAD(%) Ta=50° C Figure 6.
Switching Power Supply Technical Manual (3) Forced Airflow Models（SP-200-24） TC TC 100 100 90 90 80 80 70 70 60 60 TPC TCAP TA1 50 TPC TCAP 40 TA1 50 TA 40 30 30 TA 20 20 40 60 80 100 20 LOAD(%) Ta=25° 20 40 60 80 100 LOAD(%) Ta=50° Figure 6.6: Relationship between load and temperature for forced airflow models 6.5 Reliability and Operating Environment The operating environment of the S.P.S. will affect its reliability. (1) Vapor, Moisture If the S.P.S.
Chapter 6 Reliability 6.6 MTBF（Mean Time Between Failure） Mean Time between Failure is the expected value for reliability prediction. Estimating the reliability of the products under development or in mass production can help decide whether customers’ needs are satisfied. MTBF is the mean operating time until the reliability of the product goes down to 36.8%.
Switching Power Supply Technical Manual 6.7 Reliability test procedure for MW product Based on previous experiences, 70% of failures can be eliminated during the developing phase. Therefore, MW pays significant attention to any quality issues that may arise during development and production. (1) D.R. (Design Review): executed by RD management (a) Circuit/ architecture: reviewing the stability of the applied technology and circuits. Furthermore, compare with similar circuit from other MW products.
Chapter 6 Reliability (c) Package-delivering Simulation: review the mechanical structure and material of the products by shaking and dropping the power supply as an individual unit or a set (carton). Vibration testing conditions: (1)Waveform : Sine Wave (2)Frequency : 10 Hz ~ 500 Hz (3)Sweep Time : 10 min/sweep cycle (4)Acceleration : 2G ~ 5G (5)Orientation: X.Y.Z (6)Test Time: 1 hour in each axis (7)Sample Condition : Single unit /1 Carton (Packed) Drop Test: Package Weight Height 1-20.99 lbs( 0.45-9.
Chapter 7 Notes On Operation Chapter 7 Notes On Operation 7.1 Input Fuse Each S.P.S. has a built-in fuse for protection. Once the fuse is blown, it means that something is wrong inside the power supply. If the power supply can not operate properly after replacing with a fuse of the same type and rating, please send back to the supplier for repair. If you want to add an external fuse, be sure that the rating of this fuse should be less than or equal to the internal fuse. 7.2 Safety Inside the S.P.S.
Switching Power Supply Technical Manual MWP Equipment Case DC OUTPUT FG AC IN PUT Figure 7.1: Proper way of grounding 7.4 Input and Output Wiring (1) Input and output should be wired in opposite directions to prevent input surge and output ripple noise from interfering with each other. (2) Output wiring should be short, thick, and meet the output current rating. Also, adding a small capacitor at the load can effectively reduce the noise. (Please refer to section 2.
Chapter 7 Notes On Operation 7.5 Heat Dissipation (1) Each power supply should be installed in places with proper ventilation. (Example: installed in places with good ventilation, or inside enclosures with ventilation opening at the top) (2) Correct installation direction and location. (Example: ventilation holes face upward) (3) Each power supply should have proper heat sink. (Example: if the S.P.S.
Switching Power Supply Technical Manual 100 80 LOAD（%） 60 40 20 -10 -10 0 0 10 20 30 40 60 （VERTICAL） 55 （HORIZONTAL） 50 45 AMBIENT TEMP.（℃） Figure 7.4 Relationship between output power and temperature (derating curve) Example: If the S.P.S. is vertically installed, output power can be 100% between 0 ~ 50℃, and between 50 ~60℃ the output power should be derated. At 60℃ we need to reduce the output power to 60% of load. Above 60℃, we can not guarantee proper operation and lifetime of the unit.
Chapter 7 Notes On Operation 7.7 Remote ON/OFF Switch and Remote Sensing Wiring (1) Remote ON/OFF Switch: Using a TTL control signal connected to the +RC, -RC terminals of the S.P.S., we can control the output of the power supply. When +RC and -RC is short (0V), the S.P.S. will be ON; when it is open (the voltage between the two terminals > 4V), the S.P.S. is turned OFF. However, some models use different control logic.
Switching Power Supply Technical Manual + I/P EIN PS1 I/P P - I/P + R PS2 I/P P - Figure 7.7: Wiring of S.P.S. with built-in parallel function Notes on parallel operation: 1. Output voltage tolerance should be as small as possible (tolerance < 2%). 2. The power supplies should be paralleled using short and large diameter wiring and then connected to the load. 3. After paralleling, the available output power would be around 90% of the total power. 4.
Chapter 7 Notes On Operation + I/P EIN D1 PS1 I/P R + I/P D2 PS2 I/P - Figure 7.8: Paralleling by adding diodes in series connection 2. Add a small series resistor about 0.1Ω on the positive-output side of each power supply. This is only good for small-output-current models and also need to consider the power loss and heat problems of the resistor. Users have to check suitability of the circuit by themselves. This is generally suitable for models with small output current.
Switching Power Supply Technical Manual (1) Positive and negative terminals are connected as figure 7.10: + I/P EIN +V PS1 I/P R COM + I/P PS2 I/P R - -V Figure 7.10: Positive and negative terminals connect in series (2) Increase the output voltage (current does not change). If there is no reverse blocking diode in the power supply, we should add an external blocking diode to prevent the damage of power supply while starting up.
Chapter 7 Notes On Operation 7.11 Minimum Load Requirement To assure the regulation and stability of auxiliary outputs (CH2~CH4) on a multi-output S.P.S., we need to add a minimum load on the main channel (CH1). For example: Spec. of D-120 is 5V/6A, 24V/4A. When the output is 5V/0A, 24V/4A, the 24V output voltage will be lower than the spec.
Switching Power Supply Technical Manual 7.13 Working in High Temperature or In a Environment with Huge Temperature Difference There are high voltage and high impedance circuits in the S.P.S. So before turning on the power supply, be sure that there is no water condensation in the unit. If the S.P.S.
Chapter 7 Notes On Operation 7.16 Inrush Current Suppressing Circuit When using many S.P.S. at the same time, the huge inrush current may exceed the rating of external wiring. The following delay circuit can suppress the inrush current caused by multi-S.P.S. operation. x S I/P I/P X I/P Y PS1 - y Z I/P I/P + PS2 + - RL1 RL2 z I/P y,z Are Delay Relays I/P PSn + - RLn Figure 7.13: Delay circuit 7.
Switching Power Supply Technical Manual 7.18 Output Ripple Noise Suppression (1) Differential-Mode Noise Suppression As in figure 7.15, adding C1~C4 can reduce this form of noise. C1 and C3 are electrolytic capacitors (reference value: 47uF~100uF), while C2 and C4 are high frequency capacitors (reference value: 0.01uF~0.1uF). In general, adding C3 and C4 is good enough to reduce this noise. (2) Common-Mode Noise Suppression As in figure 7.15, adding L1, C5, and C6 can reduce the common mode noise.
Chapter 7 Notes On Operation (2). Trimming Output Voltage through External Voltage Vo + I/P EIN 100% R I/P 1~5VDC Vc - 25% 1V 5V Vc Figure 7.18: The diagram for using external voltage Figure 7.19: Dependence of output voltage on value of external voltage Notes: 1. The range of trimming voltage through external resistor or voltage control varies from model to model. Please refer to the specification before using it. 2.
Chapter 8 Technical Support Q&A Chapter 8 Technical Support Q & A This chapter consists of some of the most frequently asked questions. Due to limited number of pages available, further updates will only be done on the Mean Well website (www.meanwell.com). Please look to the FAQ section on the MW site for future updates. 8.1 Notes on choosing a switching power supply? Ans: (1) To increase the reliability of the S.P.S., we suggest users choose a unit that has a rating of 30% more power than actual need.
Switching Power Supply Technical Manual (4) Make sure that the model qualifies for the safety standards and EMC regulations you need. 8.2 How do we choose a power supply to charge a battery? Ans: MEAN WELL has ESC, SC, PA, PB series for battery charger purpose (120~360W). If these series does not meet customers’ demands and they like to choose a power supply as a charger, we advice to pick up one which over load protection (OLP) mode is constant current limiting.
Chapter 8 Technical Support Q&A 8.5 If we need a 600W output, can we use two units of S-320 connected in parallel? Ans: No, you can not do this connection because S-320 is not equipped with the parallel function. When two power supplies are connected in parallel, the one with higher output voltage will share more loading and deliver more (even “all”) power to the load and cause these two power supplies to be unbalanced.
Switching Power Supply Technical Manual 8.9 The output ground (GND) and frame ground (FG) is the same point in my system, can MEAN WELL’s power supplies be used in such system? Ans: Yes. Since our products are designed based on isolation concept, it will be no problem that the output ground (GND) and frame ground (FG) is the same point in your system. But, EMI may be affect by this connection. 8.10 During the operation of MEAN WELL power supply, there is some leakage current on the case.
Chapter 8 Technical Support Q&A Ex. In SP-150 derating curve, the ambient temperature difference in application is 5 Celsius from vertical to horizontal. The output wattage in forced cooling can be 20% higher than air cooling convection. 8.13 Why the fan is not running after turning on certain models? Ans: Some models control the fan based on internal temperature to extend its life time. For example, the Fan ON temperature for the S-240 series is ≧ 40C (RT1).
Switching Power Supply Technical Manual 8.15 What is PFC? Ans: PFC stands for Power Factor Correction. The purpose of PFC is to improve the ratio of apparent power and real power. The power factor is only 0.4~0.6 in non-PFC models. In PFC models, the power factor can reach above 0.95.
Chapter 8 Technical Support Q&A 8.18 Why the input voltage marked on the spec. sheet is 88~264 VAC while the label on the power supply says that it is 100~240VAC? Ans: During safety verification process, the agency will use a stricter standard -- ±10% (IEC60950 uses +6%, -10%) of the input voltage range labeled on the power supply to conduct the test. So, operating at the wider input voltage range as specified on the spec. sheet should be fine.
Switching Power Supply Technical Manual Handheld:0.75mA CLASSⅠ Others:3.5mA Leakage current CLASSⅡ 0.25mA --Leakage current of grounding Leakage current of case Leakage current of case Numbers of fuse 1 2 The lowest ambient temperature Refer to the definition of Manufacturer 40℃ 0.3mA 0.1mA 0.1mA 8.21 What is MTBF? Is it distinct from Life Cycle? Ans: MTBF and Life Cycle are both indicators of reliability. MEAN WELL uses MIL-HDBK-217F as the core of MTBF.
Chapter 9 Failure Correction Notes Chapter 9 Failure Correction Notes When the S.P.S. cannot function properly, please refer to the following checklist and failure correction notes in table 9.1 and 9.2. If it still cannot be fixed after each item had been checked, some internal components might be broken. Please contact the supplier for repair service. Table 9.
Switching Power Supply Technical Manual Cause Check Points Check whether the 5. Over current load has peak protection is current activated requirement? Is the right type of 6. Triggering signal used? O/P Side Remote control Can this unit be 7.
Chapter 9 Failure Correction Notes Cause Output voltage is too low Check Points Failure Correction Is the output voltage Turn clockwise to set too low through adjust the voltage VR adjustment? higher Notes 3.
Switching Power Supply Technical Manual Is the over current protection or over voltage protection 8. Protection activated? circuit is activated Confirm that the output is not being overloaded or the load is not capable of causing over- voltage No high frequency 9.
Chapter 9 Failure Correction Notes (a) The first part of number denotes C. Product Number (Made in Taiwan) D. Product Number (Made in China) R. Product which complies with RoHS (Made in Taiwan) (b) The second part of number denotes the year of manufacturing Example: 99 means 1999; A6 means 2006 (c) The third part of number denotes the month of manufacturing. A means November; B means December. (d) The fourth part of number denotes the exact order number when this model is being made.
Appendix A. Explanation Of Electrical Glossaries Abnormal Failure: An artificially induced failure of a component, usually as a result of "abnormal" testing for regulatory agency safety compliance. AC (Alternating Current): A periodic current the average value of which over a period is zero. Unless distinctly specified otherwise, the term refers to a current which reverses at regularly recurring intervals of time and which has alternately positive and negative values.
Switching Power Supply Technical Manual Auxiliary Power: A power source supplying power other than load power as required for proper functioning of a device. Bandwidth: A range of frequencies over which a certain phenomenon is to be considered. Bead: A small ferrite normally used as a high frequency inductor core. Bifilar Winding: Two conductors wound in parallel.
Appendix A. Explanation Of Electrical Glossaries Burn-In: Operating a newly manufactured power supply, usually at rated load, for a period of time in order to force component infant mortality failures or other latent defects before the unit is delivered to a customer. Capacitance: Inherent property of an electric circuit or device that opposes change in voltage. Property of circuit whereby energy may be stored in an electrostatic field.
Switching Power Supply Technical Manual Control Circuit: A circuit in a closed-loop system, typically containing an error amplifier, which controls the operation of the system to achieve regulation. Convection: The transfer of thermal energy in a gas or liquid by currents resulting from unequal temperatures.
Appendix A. Explanation Of Electrical Glossaries Differential Mode Noise : Noise that is measured between two lines with respect to a common reference point excluding common-mode noise. The resultant measurement is the difference of the noise components of the two lines. The noise between the DC output and DC return is usually measured in power supplies. Direct Current (DC): Current that the polarity doesn’t change with respect to time.
Switching Power Supply Technical Manual FET: Field Effect Transistor, a majority carrier voltage controlled transistor. Filter : A frequency-sensitive network that attenuates unwanted noise and ripple components of a rectified output. Floating Output : An output of a power supply that is not connected or referenced to any other output, usually denotes full galvanic isolation. They generally can be used as either positive or negative outputs.
Appendix A. Explanation Of Electrical Glossaries Ground Loop : An unintentionally induced feedback loop caused by two or more circuits sharing a common electrical ground. Half-Bridge Converter : A switching power supply design in which two power switching devices are used to drive the transformer’s primary side. Heat Sink: Device used to conduct away and disperse the heat generated by electronic components. High Line: Highest specified input operating voltage.
Switching Power Supply Technical Manual Isolation : Two circuits that are completely electrically separated with respect to DC potentials, and almost always also AC potentials. In power supplies, it is defined as the electrical separation of the input and output via the transformer. Isolation Transformer : A component that isolates the primary and secondary side in the switching power supply.
Appendix A. Explanation Of Electrical Glossaries Magnetic Amplifier : Sometimes abbreviated "Mag Amp," a saturating inductor that is placed in series with a power supply output for regulation purposes. Mains : The utility AC power distribution wires. Margining: Adjusting a power supply output voltage up or down from its minimal setting in order to verify system performance margin with respect to supply voltage. This is usually done electrically by a system-generated control signal.
Switching Power Supply Technical Manual Output Good : A power supply status signal which indicates that the output voltage is within a certain tolerance. An output which is either too high or too low will deactivate the Output Good signal. Output Impedance : The ratio of change in output voltage to change in load current. Output Noise : The AC component that may be present on the DC output of a power supply.
Appendix A. Explanation Of Electrical Glossaries Power Factor : The ratio of true power to apparent power in an AC circuit. In power conversion technology, power factor is used in conjunction with describing the AC input current to the power supply. Power Fail : A power supply interface signal which gives a warning that the input voltage will no longer sustain full power regulated output. Preload : A small amount of current drawn from a power supply to stabilize its operation.
Switching Power Supply Technical Manual Remote Inhibit : A power supply interface signal, usually TTL compatible, which commands the power supply to shut down one or all outputs. Remote Sense : Wires connected in parallel with power supply output cables such that the power supply can sense the actual voltage at the load to compensate for voltage drops in the output cables and/or isolation devices. Return : The designation of the common terminal for the power supply outputs.
Appendix A. Explanation Of Electrical Glossaries Split Bobbin Winding : A transformer winding technique where the primary and secondary are wound side-by-side on a bobbin with an insulation barrier between them. Standby Current : The input current drawn by a power supply when shut down by a control input (remote inhibit) or under no load. Switching Frequency : The rate at which the DC voltage is switched on and off during the pulse width modulation process in a switching power supply.
Switching Power Supply Technical Manual UPS (Uninterruptible Power Supply): A power supply which continues to supply power during a loss of input power. Two types are the stand-alone UPS, which is located external to the equipment being powered, and the battery back-up power supply, which is embedded in the equipment being powered. Voltage Balance : The difference in magnitudes, in percent, of two output voltages that have equal nominal voltage magnitudes but opposite polarities.
Appendix B. Voltage Drop Table For All Kinds Of Wiring AWG No. Composed 1A Voltage Of Drop (mV/m) (Strip/mm) Suggested Maximum CrossCross-secti section Current(A) on Area After UL 1007 UL 1015 Area(mm2) twisting(Φ) (300V 80℃) (600V 105℃) 30 358 7/0.102 0.12 ----0.051 28 222 7/0.127 0.15 0.2 0.081 26 140 7/0.16 0.35 0.5 0.129 24 88.9 11/0.16 0.7 1.0 0.205 22 57.5 17/0.16 1.4 2.0 0.326 0.8 20 37.6 26/0.16 2.8 4.0 0.517 1.0 18 22.8 43/0.16 4.2 6.0 0.823 1.3 16 14.9 54/0.18 5.6 8.0 1.309 1.6 14 9.5 41/0.
Appendix C.
Global Voltage And Plug Comparison Country Hz Voltage(V) Plug Style ASIA Taiwan Hong Kong China Macau Korea Japan Philippines Vietnam Singapore Indonesia Malaysia Brunei Jordan Iran Iraq Turkey Kuwait Saudi Arabia United Arab Emirates 50 Australia New Zealand 50 50 220/230/240 OCEANIA 240/250 230 AE B ABCD B ABC AE ABCE AB D B D BD ABDE B BE B B BD BD BD B BD ABD BD C C Hz Voltage(V) Plug Style 50 50 240 127 C AE Netherlands Belgium Luxembourg Poland Russia Romania Bulgaria Yugoslavia Gree
Appendix E. O.D.M. Form O.D.M. Guidance Form 1.0 GENERAL INFORMATION Customer Name : Contact Person : Project Engineer: Project Name : Application : Potential Q’ty : Shipping Lot: Target Price : Schedule/Prototype : Require Date: /Pilot Run : Date: /Production : Date: Other information : Purchasing: Annual Demand: Require Q’ty: Q’ty: Q’ty: 2.0 OUTPUT SPECIFICATIONS 2.1 Load Condition Output(V) Rated(A) Min.
Switching Power Supply Technical Manual Note: 1: Line Regulation: The maximum fluctuation of output voltage for input voltage range changed from low line to high line. 2: Load Regulation: The maximum fluctuation of output voltage for loading current changed from minimum load to rated load. and keep other load at 60% of rated load. 3: Accuracy Range: The output voltage is refer to tolerance that including initial set up tolerance, line regulation and load regulation.
Appendix E. O.D.M. Form 4.0 GENERAL FEATURES 4.1 Efficiency: %. This is the ratio of output power to input dissipation power. When tested at nominal input and rated load, at 25 degree C ambient. 4.2 Hold up time: The output will remain within regulation limit for ms, after loss of AC power when operating at Vac input and rated load. 4.3 Protection 4.3.1 Over voltage protection To prevent output voltage exceeding a fixed value and damaged to external load.
Switching Power Supply Technical Manual 5.0 ENVIRONMENT SPECIFICATIONS 5.1 Operating temperature range Degree C to Degree C 5.2 Storage temperature range Degree C to Degree C 5.3 Humidity % to % non condensing. 6.0 INTERNATIONAL STANDARDS 6.
Appendix E. O.D.M. Form 7.0 MECHANICAL SPECIFICATIONS 7.1 Type: P.C.B Board Enclosed case U-Bracket L-Bracket 7.2 Dimensions shown in mm by L*W*H (Fix hole of diameter and Mechanical drawing attached is required). 7.3 Connector Type Input : Type: Output : Type: 7.4 Cooling Cooling Fan is mounted on system case, Pitch: Pitch: CFM. Cooling Fan is required on Power Supply. Natural Convection. Note: Cooling fan is installed in enclosure of power supply and mechanical drawing attached is required. . 7.
