* VPOL5A-12-SMT Content 1. INTRODUCTION 2. MODELS 3. VPOL5A-12-SMT CONVERTER FEATURES 4. GENERAL DESCRIPTION 4.1 Electrical Description 4.2 Thermal Packaging and Physical Design. 5. MAIN FEATURES AND FUNCTIONS 5.1 Operating Temperature Range 5.2 Over-Temperature Protection (OTP) 5.3 Output Voltage Adjustment 5.4 Safe Operating Area (SOA) 5.5 Over Current Protection 5.6 Remote ON/OFF 5.7 UVLO (Under-Voltage Lockout) 6. SAFETY 6.1 Input Fusing and Safety Considerations. 7. APPLICATIONS 7.1 Layout Design Challenges. 7.2 Convection Requirements for Cooling 7.3 Thermal Considerations 7.4 Power De-Rating Curves 7.5 Efficiency vs Load Curves 7.6 Input Capacitance at the Power Module 7.7 Test Set-Up 7.8 VPOL5A-12-SMT Output Voltage Adustment. 7.9 Output Ripple and Noise Measurement 7.10 Output Capacitance 7.11 VPOL5-12-SMT Reflow Profile 8. MECHANICAL OUTLINE DIAGRAMS 8.1 VPOL5A-12-SMT Mechanical Outline Diagrams 8.2 VPOL5A-12-SMT Tape and Reel Dimensions V-Infinity, LLC, 9615 SW Allen Blvd Suite 103, Beaverton, OR 97005 www.v-infinity.com 1-866-372-1258 * VPOL5A-12-SMT 3. VPOL5A-12-SMT Converter Features 1. Introduction This application note describes the features and functions of VPOL5A-12-SMTof Non Isolated DC-DC Converters. These are High efficiency topology, typically 89% at 3.3Vdc Industry standard footprint highly efficient, reliable and compact, high power density, single output DC/DC converters. These "Point of Load" modules serve the needs Wide ambient temperature range, -40C to +85C Cost efficient open frame design specifically of the fixed and mobile telecommunications and computing market, employing economical distributed Power Architectures. The Programmable output voltage via external resistor from 0.75 to 5.0Vdc VPOL5A-12-SMT provide precisely regulated output voltage range from 0.75V to 5.0Vdc over a wide range of input voltage (Vi=8.3 - No minimum load requirement (Stable at all loads) Remote ON/OFF 14Vdc) and can operate over an ambient temperature range of -40 to +85. Ultra-high efficiency operation is achieved through the use of Fixed switching frequency Continuous short-circuit protection and over current protection synchronous rectification and drive control techniques. Over-temperature protection (OTP) The modules are fully protected against short circuit and over- Monotonic Startup with pre-bias at the output. temperature conditions. The world class automated manufacturing methods, together with an extensive testing and qualification program, UL/IEC/EN60950 Certified. ensure that all VPOL5A-12-SMT converter s are extremely reliable. 4. General Description 4.1 Electrical Description 2. Models The adjustable VPOL5A-12-SMT series models are shown in table1. Model Input Voltage Output Voltage Output Current VPOL5A-12-SMT 8.3 - 14VDC 0.75 - 5.0VDC 5A A block diagram of the VPOL5A-12-SMT converter is shown in Figure 1. Extremely high efficiency power conversion is achieved through the use of synchronous rectification and drive techniques. Essentially, the powerful VPOL5A-12-SMT topology is based on a non-isolated synchronous buck converter. The control loop is optimized for unconditional stability, fast transient response and a very tight line and load regulation. In a typical pre-bias application the VPOL5-12- SMT converters do not draw any reverse current at start-up. The output voltage can be adjusted from 0.75 to 5.0vdc, using the TRIM pin Table 1 VPOL5A-12-SMT Models with a external resistor. The converter can be shut down via a remote The VPOL5A-12-SMT efficiency and input current at 12Vin are shown in table2. Output Voltage Output Current 0.75V 1.2V 1.5V 1.8V 2.0V 2.5V 3.3V 5.0V 5A Input Current (mA) No Load Full Load 428mA 20 Efficiency typ. 73% 25 625mA 80% 5A 25 762mA 82% 5A 30 893mA 84% 5A 30 980mA 85% 5A 35 1197mA 87% 5A 45 1545mA 89% 5A 50 2264mA 92% 5A ON/OFF input that is referenced to ground. This input is compatible with popular logic devices; a 'positive' logic input is supplied as standard. Positive logic implies that the converter is enabled if the remote ON/OFF input is high (or floating), and disabled if it is low. The converter is also protected against over-temperature conditions. If the converter is overloaded or the ambient temperature gets too high, the converter will shut down to protect the unit. L1 Q1 +VIN +VO C1 Q2 D1 C2 COM COM Table 2 - VPOL5A-12-SMT Efficiency and Input Current R1 PWM IC ON/OFF R trim ERR AMP R2 Figure 1. Electrical Block Diagram V-Infinity, LLC, 9615 SW Allen Blvd Suite 103, Beaverton, OR 97005 www.v-infinity.com 1-866-372-1258 TRIM * VPOL5A-12-SMT 4.2 Thermal Packaging and Physical Design. The VPOL5A-12-SMT uses a multi-layer FR4 PCB construction. All 5.4 Safe Operating Area (SOA) surface mount power components are placed on one side of the PCB, and all low-power control components are placed on the other side. Figure 2 provides a graphical representation of the Safe Operating Area (SOA) of the converter. This representation assumes ambient Thus, the Heat dissipation of the power components is optimized, ensuring that control components are not thermally stressed. The operating conditions such as airflow are met as per thermal guidelines provided in Sections 7.2 and 7.3. converter is an open-frame product and has no case or case pin. The open-frame design has several advantages over encapsulated closed Vo devices. Among these advantages are: Efficient Thermal Management: the heat is removed from the Environmental: Lead free open-frame converters are more easily re-cycled. Cost Efficient: No encapsulation. Cost efficient open-frame construction. Vo,nom VOLTAGE (V) heat generating components without heating more sensitive, small signal control components. Safe Operating Area Reliable: Efficient cooling provided by open frame construction offers high reliability and easy diagnostics. Io,max Io,CL Io 5. Main Features and Functions CURRENT (A) 5.1 Operating Temperature Range VPOL5A-12-SMT converters highly efficient converter Figure 2. Maximum Output Current Safe Operating Area design has resulted in its ability to operate over a wide ambient temperature environment ( -40 to 85). Due consideration must be 5.5 Over Current Protection given to the de-rating curves when ascertaining maximum power that can be drawn from the converter. The maximum power drawn is All different voltage models have a full continuous short-circuit protection. The unit will auto recover once the short circuit is removed. influenced by a number of factors, such as: To provide protection in a fault condition, the unit is equipped with internal over-current protection. The unit operates normally once the Input voltage range. Output load current. fault condition is removed. The power module will supply up to 150% of rated current. In the event of an over current converter will go into a Air velocity (forced or natural convection). Mounting orientation of converter PCB with respect to the Airflow. hiccup mode protection. Motherboard PCB design, especially ground and power planes. These can be effective heat sinks for the converter. 5.6 Remote ON/OFF 5.2 Over-Temperature Protection (OTP) The VPOL5A-12-SMT converters are equipped with non-latching The remote ON/OFF input feature of the converter allows external circuitry to turn the converter ON or OFF. Active-high remote ON/OFF is available as standard. The VPOL5A-12-SMT converters are over-temperature protection. A temperature sensor monitors the turned on if the remote ON/OFF pin is high, or left open or floating. Setting the pin low will turn the converter `Off'. The signal level of the temperature of the hot spot (typically, top switch). If the temperature exceeds a threshold of 120C (typical) the converter will shut down, remote on/off input is defined with respect to ground. If not using the remote on/off pin, leave the pin open (module will be on). The part disabling the output. When the temperature has decreased the converter will automatically restart. number suffix "N" is Negative remote ON/OFF version. The unit is guaranteed OFF over the full temperature range if this voltage level The over-temperature condition can be induced by a variety of reasons such as external overload condition or a system fan failure. exceeds 2.8Vdc. The converters are turned on If the on/off pin input is low or left open. The recommended VPOL5A-12-SMT remote on/off drive 5.3 Output Voltage Adjustment curcuitas shown as figure 3, 4. Section 7.8 describes in detail as to how to trim the output voltage with respect to its set point. The output voltage on all models is trimmable in the range 0.75 - 5.0Vdc. V-Infinity, LLC, 9615 SW Allen Blvd Suite 103, Beaverton, OR 97005 www.v-infinity.com 1-866-372-1258 * VPOL5A-12-SMT +Vin +Vo 7.1 Layout Design Challenges. Remote ON/OFF ON/OFF Control In optimizing thermal design the PCB is utilized as a heat sink. Also Q1 VPOL5A-12-SMT Common Common Figure 3. Positive Remote ON/OFF Input Drive Circuit +Vo +Vin Q1 VPOL5A-12-SMT ON/OFF Control 7. Applications some heat is transferred from the VPOL5A-12-SMT module to the main board through connecting pins. The system designer or the end user must ensure that other components and metal in the vicinity of the VPOL5A-12-SMT meet the spacing requirements to which the system is approved. Low resistance and low inductance PCB layout traces are the norm and should be used where possible. Due consideration must also be given to proper low impedance tracks between power module, input and output grounds. The recommended VPOL5A-12-SMT foot print as shown as figure 6. Remote ON/OFF Common Common Figure 4. Negative Remote ON/OFF Input Drive Circuit 5.7 UVLO (Under-Voltage Lockout) The voltage on the Vcc pin determines the start of the operation of the Recommended Pad Layout Converter. When the input Vcc rises and exceeds about 8.0V the converter initiates a soft start. The UVLO function in the converter has a Dimensions are in Inches ( millimetes ) hysteresis (about 100mV) built in to provide noise immunity at start-up. 0.180 (4.57) 6. Safety 6.1 Input Fusing and Safety Considerations. Agency Approvals: The power Supply shall be submitted to and receive formal approval from the following test agencies. 1.The power supply shall be approved by a nationally recognized rd testing laboratory to UL/CSA 60950 3 Edition (North America) and EN60950 (International) 0.160 (4.06) VOUT 0.160 (4.06) TRIM 0.190 (4.83) GND 0.340 (8.64) 0.350 (8.89) ON/OFF 0.06 (1.5) 2. CB Certificate from an internationally recognized test house in accordance with EN 60950. 0.05 (1.3) 0.010 (0.25) VIN 0.690 (17.53) PAD SIZE MIN : 0.120" x 0.095 " MAX : 0.135" x 0.110 " Figure 6. Recommended VPOL5A-12-SMT Footprint (Top View) The VPOL5A-12-SMT converters do not have an internal fuse. However, to achieve maximum safety and system protection, always use an input line fuse. The safety agencies require a time-delay fuse with a maximum rating of 7A. V-Infinity, LLC, 9615 SW Allen Blvd Suite 103, Beaverton, OR 97005 www.v-infinity.com 1-866-372-1258 * VPOL5A-12-SMT 7.2 Convection Requirements for Cooling To predict the approximate cooling needed for the module, refer to the Power De-rating curves in Figures 10 to 13 . These de-rating curves are approximations of the ambient temperatures and airflows required to keep the power module temperature below its maximum rating. Once the module is assembled in the actual system, the module's temperature should be checked as shown in Figure 7 to ensure it does not exceed 110C. Proper cooling can be verified by measuring the power module's temperature at Q1-pin 6 as shown in Figure 8,9. W ind Tunnel Figure 9. Temperature Measurement Location for VPOL5A-12-SMT 25.4(1.0) 7.3 Thermal Considerations Bakelite The power module operates in a variety of thermal environments; however, sufficient cooling should be provided to help ensure reliable operation of the unit. Heat is removed by conduction, convection, and radiation to the surrounding environment. The thermal data presented is Power Module based on measurements taken in a set-up as shown in Figure7. Figures 10 to 13 represent the test data. Note that the airflow is parallel to the long axis of the module as shown in Figure7 for the VPOL5A-12-SMT. . The temperature at either location should not exceed 110 C. The output power of the module should not exceed the rated power for the module (VO, set x IO, max). The VPOL5A-12-SMT thermal data presented i 76.2(3.0) Thermocuple Location for measuring ambient temperature and airflow based on measurements taken in a wind tunnel. The test setup shown in Figure 7 and EUT need to solder on 33mm x 40.38mm(1.300'' x 1.59'') test pcb. Note that airflow is parallel to the long axis of the module as shown in Fig7. 12.7(0.5) Air flow Note : Dimensions are in millimeters and (inches) Figure 7. Thermal Test Setup V-Infinity, LLC, 9615 SW Allen Blvd Suite 103, Beaverton, OR 97005 www.v-infinity.com 1-866-372-1258 * VPOL5A-12-SMT VPOL5A-12-SMT (Vo=3.3V) Derating Curve 6.00 5.00 5.00 Output Current(A) Output Current(A) VPOL5A-12-SMT (Vo=5.0V) Derating Curve 6.00 4.00 3.00 0LFM 100LFM 200LFM 2.00 1.00 4.00 3.00 100LFM 1.00 200LFM 0.00 0.00 20 30 40 50 60 70 80 o Ambient Temperature( C) 90 20 100 Figure12a.Typical Power De-rating for 12V IN 5.0Vout 5.00 5.00 Output Current(A) Output Current(A) 6.00 3.00 0LFM 100LFM 200LFM 2.00 1.00 40 50 60 70 80 o Ambient Temperature( C) 90 100 VPOL5A-12-SMT (Vo=2.0V) Derating Curve 6.00 4.00 30 Figure12b.Typical Power De-rating for 12V IN 3.3Vout VPOL5A-12-SMT (Vo=2.5V) Derating Curve 0.00 4.00 3.00 0LFM 100LFM 200LFM 2.00 1.00 0.00 20 30 40 50 60 70 80 o Ambient Temperature( C) 90 100 Figure12c.Typical Power De-rating for 12V IN 2.5Vout 20 5.00 5.00 Output Current(A) 6.00 3.00 0LFM 100LFM 200LFM 2.00 1.00 0.00 40 50 60 70 80 o Ambient Temperature( C) 90 100 VPOL5A-12-SMT (Vo=1.5V) Derating Curve 6.00 4.00 30 Figure 12d.Typical Power De-rating for 12V IN 2.0Vout VPOL5A-12-SMT (Vo=1.8V) Derating Curve Output Current(A) 0LFM 2.00 4.00 3.00 0LFM 100LFM 200LFM 2.00 1.00 0.00 20 30 40 50 60 70 80 o Ambient Temperature( C) 90 100 Figure12e.Typical Power De-rating for 12V IN 1.8Vout 20 30 40 50 60 70 o 80 Ambient Temperature( C) 90 100 Figure 12f.Typical Power De-rating for 12V IN 1.5Vout V-Infinity, LLC, 9615 SW Allen Blvd Suite 103, Beaverton, OR 97005 www.v-infinity.com 1-866-372-1258 * VPOL5A-12-SMT 6.00 VPOL5A-12-SMT ( Vo=0.75 ) V Derating Curve 6.00 5.00 5.00 Output Current(A) Output Current(A) VPOL5A-12-SMT ( Vo=1.2V) Derating Curve 4.00 4.00 3.00 3.00 0LFM 100LFM 200LFM 2.00 1.00 0LFM 100LFM 200LFM 2.00 1.00 0.00 0.00 20 30 40 50 60 70 80 o Ambient Temperature( C) 90 100 Figure13a.Typical Power De-rating for 12V IN 1.2Vout 20 30 40 50 60 70 o 80 Ambient Temperature( C) 90 100 Figure 13b.Typical Power De-rating for 12V IN 0.75Vout V-Infinity, LLC, 9615 SW Allen Blvd Suite 103, Beaverton, OR 97005 www.v-infinity.com 1-866-372-1258 * VPOL5A-12-SMT VPOL5A-12-SMTVo=1.8V (Eff Vs Io) VPOL5A-12-SMTVo=1.5V (Eff Vs Io) 100% 100% 95% 95% Efficincy (%) Efficincy (%) 90% 90% 85% 8.3V 12V 14V 80% 75% 85% 80% 75% 8.3V 12V 14V 70% 65% 70% 60% 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0 5 0.5 1 Current Load (A) 2 2.5 3 3.5 4 4.5 5 Current Load (A) VPOL5A-12-SMTVo=1.2V (Eff Vs Io) VPOL5A-12-SMTVo=0.75V (Eff Vs Io) 90% 95% 85% 90% 80% Efficincy (%) 100% Efficincy (%) 1.5 85% 80% 75% 8.3V 12V 14V 70% 65% 75% 70% 65% 8.3V 12V 14V 60% 55% 60% 50% 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0 Current Load (A) V-Infinity, LLC, 9615 SW Allen Blvd Suite 103, Beaverton, OR 97005 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Current Load (A) www.v-infinity.com 1-866-372-1258 5 * VPOL5A-12-SMT The value of load regulation is defined as: 7.6 Input Capacitance at the Power Module The VPOL5A-12-SMTconverters must be connected to a low AC source Load .reg impedance. To avoid problems with loop stability source inductance should be low. Also, the input capacitors should be placed close to the converter input pins to de-couple distribution inductance. However, the external input capacitors are chosen for suitable ripple handling capability. Low ESR polymers are a good choice. They have high capacitance, high ripple rating and low ESR (typical <100mohm). VFL is the output voltage at full load VNL is the output voltage at no load Where: The value of line regulation is defined as: Electrolytic capacitors should be avoided. Circuit as shown in Figure 14 represents typical measurement methods for ripple current. Input reflected-ripple current is measured with a simulated source Inductance of 1uH. Current is measured at the input of the module. VFL VNL 100% VNL Line.reg VHL VLL 100% VLL Where: VHL is the output voltage of maximum input voltage at full load. VLL is the output voltage of minimum input voltage at full load. Current Meter A To Oscilloscope Power L1 +Vin 1uH Power + +Sense + Supply A +Vo 47uF 10UF V VPOL5A-12-SMT V CERAMIC 2*100uF Tantalum Supply +Vin Common VPOL5A-12-SMT 220uF ESR<0.1ohm Common Voltage Meter Figure 15. VPOL5A-12-SMT Test Setup Common Figure 14. Input Reflected-Ripple Test Setup 7.7 Test Set-Up The basic test set-up to measure parameters such as efficiency and load regulation is shown in Figure 15. Things to note are that this converter is non-isolated, as such the input and output share a common ground. These grounds should be connected together via low impedance ground plane in the application circuit. When testing a converter on a bench set-up, ensure that -Vin and -Vo are connected together via a low impedance short to ensure proper efficiency and load regulation measurements are being made. When testing the VPOL5A-12-SMT under any transient conditions please ensure that the transient response of the source is sufficient to power the equipment under test. We can calculate the Efficiency Load regulation and line regulation. The value of efficiency is defined as: Vo Io 100% Vin Iin Where: Vo is output voltage, Io is output current, Vin is input voltage, Iin is input current. V-Infinity, LLC, 9615 SW Allen Blvd Suite 103, Beaverton, OR 97005 www.v-infinity.com 1-866-372-1258 Load * VPOL5A-12-SMT 7.8 VPOL5A-12-SMT Output Voltage Adustment. 7.9 Output Ripple and Noise Measurement The output Voltage of the VPOL5A-12-SMT can be adjusted in the range 0.75V to 5.0V by connecting a single resistor on the motherboard The test set-up for noise and ripple measurements is shown in Figure 18. a coaxial cable with a 50ohm termination was used to prevent (shown as R trim) in Figure 17. When Trim resistor is not connected the output voltage defaults to 0.75V impedance mismatch reflections disturbing the noise readings at higher frequencies. +Vin +Vin Common Common Common Figure 18. Output Voltage Ripple and Noise Measurement Set-Up Figure 17. Trim-up Voltage Setup 7.10 Output Capacitance VPOL5A-12-SMTconverters provide unconditional stability The value of Rtrim-up defined as: ( R-Load Test Jack R trim-up Rtrim 1uF Ceramic R-Load VPOL5-12-SMT Common 10uF Tant. VPOL5A-12-SMT Trim Where: +Vo +Vo 10500 1000 ) Vo 0.75 Rtrim-up is the external resistor in ohm, Vo is the desired output voltage To give an example of the above calculation, to set a voltage of 3.3Vdc, Rtrim is given by: with or without external capacitors. For good transient response low ESR output capacitors should be located close to the point of load. For high current applications point has already been made in layout considerations for low resistance and low inductance tracks. Output capacitors with its associated ESR values have an impact on loop stability and bandwidth. The converters are designed to work with load capacitance up-to 3,000uF. It is recommended that any additional capacitance, Maximum 3,000uF and low ESR, be connected close to the point of load and outside the remote compensation point. Rtrim 10500 ( 1000 ) 3.3 0.75 7.11 VPOL5A-12-SMT Reflow Profile An example of the VPOL5A-12-SMT reflow profile is given in Figure 19. Equipment used: SMD HOT AIR REFLOW HD-350SAR Alloy: AMQ-M293TA or NC-SMQ92 IND-82088 SN63 Rtrim = 3118 ohm For various output values various resistors are calculated and provided in Table 3 for convenience. Rtrim (Kohm) Open 22 .33 13 .00 9.00 7.40 5.00 3.12 1.47 200 TEMPERATURE (C) Vo,set (V) 0.75 1.2 1.5 1.8 2.0 2.5 3.3 5.0 REFLOW PROFILE 240 160 120 80 40 Table 3 - Trim Resistor Values 0 0 30 60 90 120 150 180 210 240 TIME (SECONDS) Figure 19 VPOL5A-12-SMT Reflow Profile V-Infinity, LLC, 9615 SW Allen Blvd Suite 103, Beaverton, OR 97005 www.v-infinity.com 1-866-372-1258 * VPOL5A-12-SMT 8. Mechanical Outline Diagrams 8.2 VPOL5A-12-SMT Tape and Reel Dimensions 8.1 VPOL5A-12-SMT Mechanical Outline Diagrams The Tape Reel dimensions for the VPOL5A-12-SMT module is shown in Figure 22. Dimensions are in millimeters and inches Tolerance: x.xx 0.02 in. (0.5mm) , x.xxx 0.010 in. (0.25 mm) unless otherwise noted t BOTTOM VIEW OF BOARD 0.80 (20.3) 0.190 (4.83) 0.160 (4.06) GND 0.35 (8.9) 0.160 (4.06) TRIM 0.24 (6.09) max. 0.180 (4.06) VOUT 0.065 (1.65) 0.340 (8.64) 0.450 (11.43) VIN 0.062 (1.57) ON/OFF 0.06 (1.5) Surface Mount Contact 5 Places 0.090 0.05 (1.3) (2.29) Dimensions are in Inches (millimeters) W Ao Tolerances :x.xx 0.02in.( x.x 0.5mm) , unless otherwise noted x.xxx 0.010in. ( x.xx 0.25mm) Bo Ko P Figure 21 VPOL5A-12-SMT Mechanical Outline Diagram F E D D1 Po P2 t Figure 22 - VPOL5A-12-SMT Tape and Reel Dimensions V-Infinity, LLC, 9615 SW Allen Blvd Suite 103, Beaverton, OR 97005 www.v-infinity.com 1-866-372-1258