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| rev. page date 1 of 14 08/2007 PART NUMBER: VPOL20A-12W-SIP DESCRIPTION: point of load converter features * industry standard pin out * high efficiency to 94% * 300 KHz switching frequency * 6.0-14 VDC wide input range * 0.75-5.0 VDC wide output range * over temperature protection * continuous short circuit protection * remote on/off * cost-efficient open frame design * UL/C-UL60950 certified * output voltage sequencing (tracking) * power good signal 1. INTRODUCTION 2. VPOL20A-12W-SIP CONVERTER FEATURES 3. GENERAL DESCRIPTION 3.1 Electrical Description 3.2 Thermal Packaging and Physical Design. 4. TECHNICAL SPECIFICATIONS 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) 5.8 Output Voltage Sequencing (Tracking) 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 Remote Sense Compensation 7.9 VPOL20A-12W-SIP Series Output Voltage Adustment. 7.10 Output Ripple and Noise Measurement 7.11 Output Capacitance 8. MECHANICAL OUTLINE DIAGRAMS 8.1 VPOL20A-12W-SIP Mechanical Outline Diagrams 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 rev. page date 2 of 14 08/2007 PART NUMBER: VPOL20A-12W-SIP DESCRIPTION: point of load converter converter is also protected against over-temperature conditions. If the 1. Introduction This application note describes the features and functions of V-Infinity's VPOL20A-12W-SIP series of Non Isolated DC-DC Converters. These are highly efficient, reliable and compact, high power density, single output DC/DC converters. These "Point of Load" modules serve the needs specifically of the fixed and mobile telecommunications and computing market, employing economical distributed Power Architectures. The VPOL20A-12W-SIP series provide precisely regulated output voltage range from 0.7525V to 5.0Vdc over a wide range of input voltage (Vi=6.0 - 14Vdc) and can operate over an ambient temperature range of -40 to +85. Ultradrive control techniques. The modules are fully protected against short circuit and overtemperature conditions. V-Infinity's world class automated manufacturing methods, together with an extensive testing and qualification program, ensure that all VPOL20A-12W-SIP series converters are extremely reliable. high efficiency converter is overloaded or the ambient temperature gets too high, the converter will shut down to protect the unit. Q1 +VIN L1 +VO C1 Q2 D1 R sense C2 +SENSE COM COM R1 PGood ON/OFF SEQ PWM IC ERR AMP R trim R2 operation is achieved through the use of synchronous rectification and TRIM Figure 1. Electrical Block Diagram 3.2 Thermal Packaging and Physical Design. The VPOL20A-12W-SIP series uses a multi-layer FR4 PCB construction. All surface mount power components are placed on one side of the PCB, and all low-power control components are placed on the other side. Thus, the Heat dissipation of the power components is optimized, ensuring that control components are not thermally stressed. The converter is an open-frame product and has no case or case pin. The open-frame design has several advantages over encapsulated closed devices. Among these advantages are: Efficient Thermal Management: the heat is removed from the heat generating components without heating more sensitive, small signal control components. Environmental: Lead free open-frame converters are more easily re-cycled. Cost Efficient: No encapsulation. Cost efficient open-frame construction. Reliable: Efficient cooling provided by open frame construction offers high reliability and easy diagnostics. 2. VPOL20A-12W-SIP Converter Features High efficiency topology, typically 94% at 5.0Vdc Industry standard footprint Wide ambient temperature range, -40C to +85C Cost efficient open frame design Programmable output voltage via external resistor from 0.7525 to 5.0Vdc No minimum load requirement (Stable at all loads) Remote ON/OFF Remote sense compensation Fixed switching frequency Continuous short-circuit protection and over current protection Over-temperature protection (OTP) Monotonic Startup with pre-bias at the output. UL/IEC/EN60950 Certified. Output Voltage Sequencing( Tracking ) Power Good Signal (Option) 3. General Description 3.1 Electrical Description A block diagram of the VPOL20A-12W-SIP Series 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 VPOL20A-12W-SIP series 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 VPOL20A-12W-SIP series converters do not draw any reverse current at start-up. The output voltage can be adjusted from 0.7525 to 5.0vdc, using the TRIM pin with a external resistor. The converter can be shut down via a remote 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 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 rev. page date 3 of 14 08/2007 PART NUMBER: VPOL20A-12W-SIP DESCRIPTION: point of load converter 4. Technical Specifications (All specifications are typical at nominal input, full load at 25C unless otherwise noted.) PARAMETER ABSOLUTE MAXIMUM RATINGS Input Voltage Continuous Operating Temp erature See Thermal Considerations Section Storage Temperature NOTES and CONDITIONS ALL ALL Device Min. Typical Max. Units 0 -40 ALL -55 16 +85 +125 Vdc C C INPUT CHARACTERISTICS Operating Input Voltage Input Under-Voltage Lockout Turn-On Voltage Threshold Turn-Off Voltage Threshold Lockout Hysteresis Voltage Maximum Input Current Vin=0 to 14Vdc , Io=Io,max. Vo=0.7525V Vo=1.2V Vo=1.5V Vo=1.8V Vo=2.0V Vo=2.5V Vo=3.3V Vo=5.0V Shutdown input idle current Vo=4.5V Vo=5.0V ALL ALL ALL ALL ALL 6.0 6.5 5.0 4.0 1.0 19 40 50 50 50 60 65 75 95 10 0.4 220 12 12 14 14 Vdc Vdc Vdc Vdc A No-Load Input Current ALL mA Off Converter Input Current Inrush Current (I t) Input Reflected-Ripple Current 2 ALL ALL mA As mA 2 P-P thru 1uH inductor, 5Hz to 20MHz ALL OUTPUT CHARACTERISTIC Output Voltage Set Point Output Voltage Trim Adjustment Range Output Voltage Regulation Load Regulation Line Regulation Tempera ture Coefficient Output Voltage Ripple and Noise Peak-to-Peak RMS External Capacitive Load Operating Output Current Range Output DC Current-Limit Inception Shout Circuit Protection Sequency Slew Rate Capability Sequencing Delay Time Tracking Accuracy Power Good Signal Power up Power down Asserted Logic High Vo ALL Suffix "P" 90 Output Voltage =90% Nominal Output Voltage Continuous with Hiccup Mode dVSEQ/dt 10 200 400 110 0.1 1.0 V/ms ms mV % Io=Io.min to Io.max Vin=low line to high line Ta=-40 C to 85C 5Hz to 20MHz bandwidth Full Load, 1uF ceramic and 10uF tantalum Full Load, 1uF ceramic and 10uF tantalum Low ESR ALL ALL ALL ALL ALL 0 24 30 75 30 8000 20 36 mV mV uF A A ALL ALL ALL -0.5 -0.2 -0.03 +0.5 +0.2 +0.03 % % %/C Vin=Nominal Vin , Io=Io.max, Tc=25 Selected by an external resistor ALL ALL -1.5% Vo,set +1.5% 0.7525 5.0 Vdc Vdc 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 rev. page date 4 of 14 08/2007 PART NUMBER: VPOL20A-12W-SIP DESCRIPTION: point of load converter Error Brand Setting Time (within 1% Vout nominal) 50% Step Load Change, di/dt=2.5A/us 50% Step Load Change, di/dt=2.5A/us ALL ALL 200 200 mV us EFFICIENCY Vo=0.7525V Vo=1.2V Vo=1.5V Vo=1.8V Vo=2.0V Vo=2.5V Vo=3.3V Vo=5.0V Non-isolation 78 84 87 88 89 90 92 94 0 100% Load ALL % ISOLATION CHARACTERISTICS Input to Output ALL Vdc FEATURE CHARACTERISTICS Switching Frequency ON/OFF Control, Positive Logic Remote On/Off Logic Low (Module Off) Logic High (Module On) ALL VPOL20A-12W-SIP or Open Circuit VPOL20A-12W-SIP ALL ALL ALL ALL ALL ALL per MIL-HDBKALL ALL 2.4x0.51 x0.327 inches (61x12.95x8.3 mm) 3 3 4 130 0.9 11 0 2.8 0 300 0.4 Vin 0.4 Vin 1 1 KHz Vdc Vdc Vdc Vdc mA mA ms ms ms ON/OFF Control, Negative Logic Remote On/Off Logic Low (Module On) or Open Circuit Logic High (Module Off) ON/OFF Current (for both remote on/off logic) Leakage Current (for both remote on/off logic) Turn-On Delay and Rise Time Turn-On Delay Time, From On/Off Control Turn-On Delay Time, From Input Output Voltage Rise Time Over Temperature Protection Ion/off at Von/off =0.0V Logic High, Von/off=14V Von/off to 10%Vo,set Vin,min. to 10%Vo,set 10%Vo,set to 90%Vo,set C M hours grams GENERAL SPECIFICATIONS MTBF Weight Dimensions Io=100%of Io.max;Ta=25 217F 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 rev. page date 5 of 14 08/2007 PART NUMBER: VPOL20A-12W-SIP DESCRIPTION: point of load converter 5. Main Features and Functions 5.1 Operating Temperature Range V-Infinity's VPOL20A-12W-SIP series converters highly efficient converter design has resulted in its ability to operate over a wide ambient temperature environment ( -40C to 85C). Due consideration must be given to the de-rating curves when ascertaining maximum power that can be drawn from the converter. The maximum power drawn is influenced by a number of factors, such as: Input voltage range. Output load current. Air velocity (forced or natural convection). Mounting orientation of converter PCB with respect to the Airflow. Motherboard PCB design, especially ground and power planes. These can be effective heat sinks for the converter. removed. The power module will supply up to 150% of rated current. In the event of an over current converter will go into a hiccup mode protection. 5.6 Remote ON/OFF 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 VPOL20A-12W-SIP is turned on if the remote ON/OFF pin is high(=Vin), or left open. Setting the pin low(<0.4Vdc) will turn the converter `Off'. The signal level of the 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 number suffix "N" is Negative remote ON/OFF version. The unit is guaranteed OFF over the full temperature range if this voltage level exceeds 2.8Vdc. The converters are turned on If the on/off pin input is low (<0.4Vdc) or left open. The recommended remote on/off drive circuit as shown as figure 3, 4. 5.2 Over-Temperature Protection (OTP) The VPOL20A-12W-SIP Series converters are equipped with nonlatching over-temperature protection. A temperature sensor monitors the temperature of the hot spot (typically, top switch). If the temperature exceeds a threshold of 130C (typical) the converter will shut down, disabling the output. When the temperature has decreased the converter will automatically restart. The over-temperature condition can be induced by a variety of reasons such as external overload condition or a system fan failure. +Vin Remote ON/OFF +Vo ON/OFF Control Q1 VPOL20A-12W-SIP Common Common 5.3 Output Voltage Adjustment 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 0.7525 - 5.0Vdc. Figure 3. Positive Remote ON/OFF Input Drive Circuit +Vin +Vo 5.4 Safe Operating Area (SOA) Figure 2 provides a graphical representation of the Safe Operating Area (SOA) of the converter. This representation assumes ambient operating conditions such as airflow are met as per thermal guidelines provided in Sections 7.2 and 7.3. Q1 VPOL20A-12W-SIP ON/OFF Control Remote ON/OFF Common Common Vo Figure 4. Negative Remote ON/OFF Input Drive Circuit Vo,nom VOLTAGE (V) Safe Operating Area Io,max Io,CL Io CURRENT (A) Figure 2. Maximum Output Current Safe Operating Area 5.5 Over Current Protection All different voltage models have a full continuous short-circuit protection. The unit will auto recover once the short circuit is removed. To provide protection in a fault condition, the unit is equipped with internal overcurrent protection. The unit operates normally once the fault condition is 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 rev. page date 6 of 14 08/2007 PART NUMBER: VPOL20A-12W-SIP DESCRIPTION: point of load converter 5.7 UVLO (Under-Voltage Lockout) The voltage on the Vcc pin determines the start of the operation of the Converter. When the input Vcc rises and exceeds about 5.0V the converter initiates a soft start. The UVLO function in the converter has a hysteresis (about 1V) built in to provide noise immunity at start-up. Power start up with SEQ signal Input Voltage=12Vdc Master DC/DC output voltage (CH1) = 5Vdc Salve DC/DC output voltage (CH2)=3.3Vdc Sequencing voltage= 0.67V/msec 5.8 Output Voltage Sequencing (Tracking) The VPOL20A-12W-SIP series including a sequencing feature. It is able implement various types of output voltage sequencing in customer applications, VPOL20A-12W-SIP series is accomplishable through an additional sequencing pin. When not using the sequencing feature, tie the SEQ pin to +Vin. When the signal voltage is applied to the SEQ pin, the output voltage tracks this voltage until the output reaches the set point voltage. The SEQ voltage needs to be set higher than the set point of the module. The output voltage will be follow by the voltage on the SEQ pin. On the multiple modules application, we can connect SEQ pin and input signal voltage together to apply on the SEQ pin. Customers can get multiple modules to track their output voltages to follow the voltage of the SEQ pin. To control this module for sequen cing, when the input voltage applied to the module. The on/off pin is left unconnected so that the module is ON by default. After applying input voltage to the module, a minimum of 10msec delay is required before applying voltage on the SEQ pin and slew rate of the voltage on the SEQ pin see technical specifications " dVSEQ/dt ". After 10msec delay, an Analog voltage is applied to the SEQ pin and the output voltage of the module will track this voltage until output voltage reaches the set point voltage. To initiate simultaneous shutdown of the modules, the SEQ pin voltage is lowered in a controlled manner. Output voltage of the modules track the voltages below their set-point voltage voltages. A valid input voltage must be maintained until the tracking and output voltages reach ground potential to ensure a controlled shutdown of the modules. A typical example testing circuit used master DC/DC converter and VPOL20A-12W-SIP Module as shown as below: +Vin Power Supply Common Common C1 CH1 Master DC/DC Converter R1 Load +Vo Figure 6. Example testing circuit of sequencing function Power turn off with SEQ signal voltage Input Voltage=12Vdc (CH1) Master DC/DC output voltage (CH2) = 5Vdc Salve DC/DC output voltage (CH3)=3.3Vdc + Figure 7. Example testing circuit of sequencing function +Vin +Vo SEQ CH2 VPOL20A-12W-SIP Common Common C2 R2 CH3 Load 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 testing laboratory to UL/CSA 60950 3 Edition (North America) and EN60950 (International) rd Figure 5. Example testing circuit of sequencing function 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 rev. page date 7 of 14 08/2007 PART NUMBER: VPOL20A-12W-SIP DESCRIPTION: point of load converter 2. CB Certificate from an internationally recognized test house in accordance with EN 60950. The VPOL20A-12W-SIP series 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 25A. 7.1 Layout Design Challenges. In optimizing thermal design the PCB is utilized as a heat sink. Also some heat is transferred from the VPOL20A-12W-SIP 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 VPOL20A-12W-SIP series 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 VPOL20A-12W-SIP footprint as shown as figure 8. LAYOUT PAT TERN TOP VIEW All Dimmension In Inches(mm) Tolerance : .XX= O 0.02 ( .X= O ) 0.5 .XXX= O 0.010 ( .XX= O 0.25 ) 0.33(8.4) 0.29(7.4) 1.1mm PLATED THROUGH HOLE 1.6mm PAD SIZE Figure 8. Recommended VPOL20A-12W-SIP Footprint 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 rev. page date 8 of 14 08/2007 PART NUMBER: VPOL20A-12W-SIP DESCRIPTION: point of load converter 7. Applications 7.2 Convection Requirements for Cooling To predict the ap proximate cooling needed for the module, refer to the Power De-rating curves in Figure 11. 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 9 to ensure it does not exceed 120C. Proper cooling can be verified by measuring the power module's temperature at " Tref " as shown in Figure 10. Wind Tunnel PWBs Figure 10. Temperature Measurement Location for VPOL20A-12W-SIP 7.3 Thermal Considerations 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 based on measurements taken in a set-up as shown in Figure 9. Figure 11 represents the test data. Note that the airflow is parallel to the long axis of the module as shown in Figure7 for the VPOL20A-12W-SIP. The temperature at " Tref " location should not exceed 120 C. The output power of the module should not exceed the rated power for the module (VO, set x IO, max). The thermal data presented is based on measurements taken in a wind tunnel. The test setup shown in Figure 7 25.4(1.0) Power Module and EUT need to solder on 53.8mm x 43.2mm(2.12'' x 1.7'') test pcb. Note that airflow is parallel to the long axis of the module as shown in Fig10. 76.2(3.0) Thermocuple Location for measuring ambient temperature and airflow 12.7(0.5) Air flow Note : Dimensions are in millimeters and (inches) Figure 9. Thermal Test Setup 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 rev. page date 9 of 14 08/2007 PART NUMBER: VPOL20A-12W-SIP DESCRIPTION: point of load converter TYPICAL POWER DERATING FOR 5 Vin 3.3 Vout 25.0 20.0 Output Current(A) 15.0 10.0 5.0 0.0 0LFM 100LFM 200LFM 300LFM 400LFM 0 10 20 30 40 50 60 70 80 90 100 Ambient Temperature( oC) NOTE: 1. specific input & output derating curves available, please contact V-Infinity for detail 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 rev. page date 10 of 14 08/2007 PART NUMBER: VPOL20A-12W-SIP DESCRIPTION: point of load converter 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 rev. page date 11 of 14 08/2007 PART NUMBER: VPOL20A-12W-SIP DESCRIPTION: point of load converter VPOL20A-12W-SIP Vo=1.8V (Eff Vs Io) 100% 95% 100% 95% VPOL20A-12W-SIP Vo=1.5V (Eff Vs Io) Efficincy (%) Efficincy (%) 90% 85% 80% 75% 70% 0 2 4 6 8 10 12 14 16 18 20 90% 85% 80% 75% 70% 0 2 4 6 8 10 12 14 16 18 20 6.0V 12V 14V 6.0V 12V 14V Current Load (A) VPOL20A-12W-SIP Vo=1.2V (Eff Vs Io) 100% 95% Current Load (A) VPOL20A-12W-SIP Vo=0.75V (Eff Vs Io) 100% 95% Efficincy (%) Efficincy (%) 90% 85% 80% 75% 70% 65% 60% 0 2 4 6 8 10 12 14 16 18 20 90% 85% 80% 75% 70% 65% 60% 0 2 4 6 8 10 12 14 16 18 20 6.0V 12V 14V 6.0V 12V 14V Current Load (A) Current Load (A) 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 rev. page date 12 of 14 08/2007 PART NUMBER: VPOL20A-12W-SIP DESCRIPTION: point of load converter 7.6 Input Capacitance at the Power Module The VPOL20A-12W-SIP converters must be connected to a low AC source impedance. To avoid probl ems 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). Electrolytic capacitors should be avoided. Circuit as shown in Figure 12 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. To Oscilloscope L1 1uH Power Supply + 2*100uF Tantalum 1000uF Electronlyic ESR<0.1ohm Com Com +Vin +Vo Power Supply + Line.reg = VHL _ VLL x100 % 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 +Vin +Vo +Sense A V 100uF Voltage Meter VPOL20A-12W-SIP Common Common V Load Figure 13. VPOL20A-12W-SIP Series Test Setup 7.8 Remote Sense Compensation Remote Sense regulates the output voltage at the point of load. It minimizes the effects of distribution losses such as drops across the connecting pin and PCB tracks (see Figure 14). Please note however, VPOL20A-12W-SIP R1 C2 Load the maximum drop from the output pin to the point of load should not exceed 500mV for remote compensation to work. The amount of power delivered by the module is defined as the output voltage multiplied by the output current (VO x IO). When using TRIM UP, the output voltage of the module will increase which, if the same output current is maintained, increases the power output by the module. Make sure that the maximum output power of the module remains at or below the maximum rated power. When the Remote Sense feature is not being used, leave sense pin disconnected. Figure 12. 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 13. 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 V-Infinity's VPOL20A-12W-SIP series 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: Figure 14. Circuit Configuration for Remote Sense Operation Distribution Losses +Vin +Vo +Sense VPOL20A-12W-SIP R-Load Vo x Io x100% c= Vin x Iin Common Where: Vo is output voltage, Io is output current, Vin is input voltage, Iin is input current. The value of load regulation is defined as: Common Distribution Losses Load .reg = Where: VFL _ VNL x100% VNL VFL is the output voltage at full load VNL is the output voltage at no load The value of line regulation is defined as: 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 rev. page date 13 of 14 08/2007 PART NUMBER: VPOL20A-12W-SIP DESCRIPTION: point of load converter 7.9 VPOL20A-12W-SIP Series Output Voltage Adustment. The output Voltage of the VPOL20A-12W-SIP can be adjusted in the range 0.7525V to 5.0V by connecting a single resistor on the motherboard (shown as Rtrim) in Figure 15. When Trim resistor is not connected the output voltage defaults to 0.7525V Power COPPER STRIPS VO SCOPE 1uF LOAD 10uF C1 Supply + COM VIN VPOL20A-12W-SIP +Vin +Vo Trim Figure 16. Output Voltage Ripple and Noise Measurement Set-Up 7.11 Output Capacitance R-Load R trim-up V-Infinity's VPOL20A-12W-SIP series converters provide unconditional stability 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. V-Infinity's converters are designed to work with load capacitance up-to 8,000uF. It is reco mmended that any additional capacitance, typically 1,000uF and low ESR (<20mohm), be connected close to the point of load and outside the remote compensation point. VPOL20A-12W-SIP Common Common Figure 15. Trim-up Voltage Setup The value of Rtrim-up defined as: Rtrim = ( Where: Rtrim-up 10500 _ 1000 ) Vo _ 0.7525 is the external resistor in ohm, Vo is the desired output voltage To give an exa mple of the above calculation, to set a voltage of 3.3Vdc, Rtrim is given by: Rtrim = ( Rtrim = 3.122K ohm 10500 _ 1000 ) _ 3.3 0.7525 For various output values various resistors are calculated and provided in Table 3 for co nvenience. Vo,set (V) 0.7525 1.2 1.5 1.8 2.0 2.5 3.3 5.0 Rtrim (Kohm) Open 22.46 13.05 9.024 7.417 5.009 3.122 1.472 Table 3 - Trim Resistor Values 7.10 Output Ripple and Noise Measurement The test set-up for noise and ripple measurements is shown in Figure 16. a coaxial cable with a 50ohm termination was used to prevent impedance mismatch reflections disturbing the noise readings at higher frequencies. The Output Ripple & Noise is measured with 1uf ceramic and 10uf tantalum. The measured position are 50mm to 75mm(2" to 3") from the module. The "C1" is 200uF Tant alum capacitor ESR< 25m 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 rev. page date 14 of 14 08/2007 PART NUMBER: VPOL20A-12W-SIP DESCRIPTION: point of load converter 8. Mechanical Outline Diagrams 8.1 VPOL20A-12W-SIP Mechanical Outline Diagrams 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 SIZE SIP 2.40(61.0) 0.327(8.30)max. 0.23(5.8) 12345 0.14(3.6) 0.100(2.54) 0.400(10.20) 0.025(0.64) 6 7 8 9 10 11 12 0.510(12.95) 0.010(0.25) min. 0.250(6.35) 0.28(7.1) 0.025(0.64) 0.900(22.90) 0.29(7.4) LAYOUT PAT TERN TOP VIEW All Dimmension In Inches(mm) Tolerance : .XX= O 0.02 ( .X= O ) 0.5 .XXX= O 0.010 ( .XX= O 0.25 ) 0.33(8.4) 1.1mm PLATED THROUGH HOLE 1.6mm PAD SIZE PIN CONNECTION Pin FUNCTION +Output 1 +Output 2 3 +Sense +Output 4 5 Common No Pin / PGood 6 Common 7 +V Input 8 +V Input 9 10 Sequency 11 Trim 12 On/Off Control Figure 17 VPOL20A-12W-SIP Mechanical Outline Diagram 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 |
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