For more information, please visit the product page. rev. PART NUMBER: VPOL5A-12-SIP page 1 of 12 date 08/2007 DESCRIPTION: point of load converter features * industry standard pin out * high efficiency to 92% * 300 KHz switching frequency * 8.3-14 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-UL60950-1 (E222736) certified 1. INTRODUCTION 2. VPOL5A-12-SIP CONVERTER FEATURES 7. APPLICATIONS 7.1 Layout Design Challenges. 7.2 Convection Requirements for Cooling 3. GENERAL DESCRIPTION 3.1 Electrical Description 7.3 Thermal Considerations 3.2 Thermal Packaging and Physical Design. 7.4 Power De-Rating Curves 4. TECHNICAL SPECIFICATIONS 7.5 Efficiency vs Load Curves 5. MAIN FEATURES AND FUNCTIONS 5.1 Operating Temperature Range 7.6 Input Capacitance at the Power Module 5.2 Over-Temperature Protection (OTP) 7.8 VPOL5A-12-SIP Output Voltage Adustment. 5.3 Output Voltage Adjustment 7.9 Output Ripple and Noise Measurement 5.4 Safe Operating Area (SOA) 7.10 Output Capacitance 5.5 Over Current Protection 5.6 Remote ON/OFF 7.7 Test Set-Up 8. MECHANICAL OUTLINE DIAGRAMS 8.1 VPOL5A-12-SIP Mechanical Outline Diagrams 5.7 UVLO (Under-Voltage Lockout) 6. SAFETY 6.1 Input Fusing and Safety Considerations. 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 For more information, please visit the product page. rev. PART NUMBER: VPOL5A-12-SIP page 2 of 12 date 08/2007 DESCRIPTION: point of load converter If the converter is overloaded or the ambient temperature gets too 1. Introduction high, the converter will shut down to protect the unit. L1 Q1 This application note describes the features and functions of CUI INC's +VIN +VO VPOL5A-12-SIP series of non-isolated dc-dc converters. These are highly efficient, reliable and compact, high power density, single output C1 Q2 D1 C2 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 VPOL5A-12-SIP series provide precisely regulated output voltage range COM COM R1 from 0.75V to 5.0Vdc over a wide range of input voltage (Vi=8.3 – 14Vdc) and can operate over an ambient temperature range of –40°C to +85°C. Ultra-h igh efficiency operation is achieved through the use of PWM IC ON/OFF R trim ERR AMP TRIM R2 synchronous rectification and drive control techniques. The modules are fully protected against short circuit and overtemperature conditions. CUI INC's world class automated Figure 1. Electrical Block Diagram manufacturing methods, together with an extensive testing and qualification program, ensure that all VPOL5A-12-SIP series converters 3.2 Thermal Packaging and Physical Design. are extremely reliable. The VPOL5A-12-SIP series uses a multi-layer FR4 PCB construction. All surface mount power components are placed on one side of the 2. VPOL5A-12-SIP Converter Features PCB, and all low-power control components are placed on the other side. Thus, the Heat dissipation of the power components is optimized, High efficiency topology, typically 89% at 3.3Vdc ensuring that control components are not thermally stressed. The Industry standard footprint converter is an open-frame product and has no case or case pin. The Wide ambient temperature range, -40°C to +85°C open-frame design has several advantages over encapsulated closed Cost efficient open frame design devices. Among these advantages are: Programmable output voltage via external resistor from 0.75 to 5.0Vdc No minimum load requirement (Stable at all loads) Remote ON/OFF 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. 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. 3. General Description 3.1 Electrical Description A block diagram of the VPOL5A-12-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 VPOL5A-12-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 VPOL5A-12SIP series 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 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 converter is also protected against over-temperature conditions. 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 For more information, please visit the product page. For more information, please visit the product page. rev. 4 of 12 date 08/2007 DESCRIPTION: point of load converter PART NUMBER: VPOL5A-12-SIP P A R A ME T E R DYNAMIC CHARACTERISTICS page N O T E S a n d C O N D IT IO N S Device Er ror Brand 5 0 % Ste p L oa d Cha nge , di/dt=0 . 1 A /us Setting Time (within 1% Vout nominal) 50% Step Load Change, di/dt=0.1A/us Min. Typical Max. Units AL L 200 mV AL L 200 us Output Voltage Transient Response EFFICIENCY 100% Load Vo=0.75V Vo=1.2V Vo=1.5V Vo=1.8V Vo=2.0V Vo=2.5V Vo=3.3V Vo=5.0V ALL N on-isolation AL L 73 80 82 84 85 87 89 92 % ISOLATION CHARACTERISTICS I nput to O utput 0 Vdc FEATURE CHARACTERISTICS Switching Fre uency ALL 300 ON/OFF Control, Positive Logic Remote On/O Logic Low (Module O ) L ogic H igh ( Module O n) or O pe n C irc uit Standard Model 0 ON/OFF Control, Negative Logic Remote On/O Logic Low (Module On) Logic High (Module O ) or Open Circuit Su x “N” Model 0 2.8 O N /O F F C urre nt ( for both re mote on/off logic ) L e a k a ge C urre nt ( for both re mote on/off logic ) Turn-On Delay and Rise Time T urn -O n D e la y T ime , F rom O n/O ff C ontrol T urn -O n D e la y T ime , F rom I nput O utput V olta ge R is e T ime Over Temperature Protection Vin KHz 0.4 Vdc Vdc 0.4 Vin Vdc Vdc 1 1 mA mA I on/off a t V on/off =0 . 0 V L ogic H igh, V on/off=1 4 V AL L AL L V on/off to 1 0 % V o, s e t V in, min. to 1 0 % V o, s e t 1 0 % V o, s e t to 9 0 % V o, s e t AL L AL L AL L ALL 3. 5 3. 5 3. 5 120 ms ms ms °C ALL 1.5 M hours ALL 2.3 grams GENERAL SPECIFICATIONS MTBF Weight Dimensions V P O L 5 A -1 2 -S I P pa c k a ge s Io=100% of Io.max Ta=2 5°C per MIL- HDBK - 217F 0 . 9 x 0 . 4 x 0 . 2 2 inc he s ( 2 2 . 9 x 1 0 . 1 6 x 5 . 6 mm) 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 For more information, please visit the product page. rev. PART NUMBER: VPOL5A-12-SIP page 5 of 12 date 08/2007 DESCRIPTION: point of load converter 5. Main Features and Functions 5.4 Safe Operating Area (SOA) 5.1 Operating Temperature Range (SOA) of the converter. This representation assumes ambient Figure 2 provides a graphical representation of the Safe Operating Area CUI INC’s VPOL5A-12-SIP series converters highly efficient converter operating conditions such as airflow are met as per thermal guidelines design has resulted in its ability to operate over a wide ambient provided in Sections 7.2 and 7.3. temperature environment ( -40°C to 85°C). Due consideration must be given to the de-rating curves when ascertaining maximum power that Vo can be drawn from the converter. The maximum power drawn is influenced by a number of factors, such as: Input voltage range. 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. Vo,nom VOLTAGE (V) Output load current. Safe Operating Area 5.2 Over-Temperature Protection (OTP) Io,max Io,CL Io The VPOL5A-12-SIP Series converters are equipped with non-latching CURRENT (A) over-temperature protection. A te mperature sensor monitors the temperature of the hot spot (typically, top switch). If the temperature exceeds a threshold of 120°C (t ypical) the converter will shut down, disabling the output. When the temperature has decreased the Figure 2. Maximum Output Current Safe Operating Area converter will automatically restart. 5.5 Over Current Protection The over-temperature condition can be induced by a variety of reasons All different voltage models have a full continuous short-circuit such as external overload condition or a system fan failure. protection. The unit will auto recover once the short circuit is removed. To provide pr otection in a fault condition, the unit is equipped with 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 0.75 – 5.0Vdc. internal over-current protection. The unit operates normally once the 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 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 VPOL5A-12-SIP series converters are 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 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 or left open. The recommended VPOL5A-12-SIP remote on/off drive circuit as shown as figure 3, 4. 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 For more information, please visit the product page. rev. 6 of 12 date 08/2007 DESCRIPTION: point of load converter PART NUMBER: VPOL5A-12-SIP +Vin ON/OFF Control page +Vo 7. Applications 7.1 Layout Design Challenges. Remote ON/OFF Q1 In optimizing thermal design the PCB is utilized as a heat sink. Also VPOL5A-12-SIP some heat is transferred from the VPOL5A-12-SIP module to the main board through connecting pins. The system designer or the end user Common Common must ensure that other components and metal in the vicinity of the VPOL5A-12-SIP series meet the spacing requirements to which the Figure 3. Positive Remote ON/OFF Input Drive Circuit +Vin Q1 ON/OFF Control +Vo VPOL5A-12-SIP 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-SIP footprint as shown as figure 5. Remote ON/OFF Common Common Figure 4. Negative Remote ON/OFF Input Drive Circuit 5.7 UVLO (Under-Voltage Lockout) 1.1mm PLATED THR OUGH HOLE 1.6mm PAD SIZE 0.20(5.1) LAYOUT PA TTERN TOP VIEW 0.24(6.1) All Dimmension In Inches(mm) Tol erance : .XX= ±0.02 ( ±0.5 ) .XXX= ±0.010 ( ±0.25 ) Figure 5. Recommended VPOL5A-12-SIP Footprint The voltage on the Vcc pin determines the start of the operation of the 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 hysteresis (about 100mV) built in to provide noise immunity at start-up. 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) 2. CB Certificate from an internationally recognized test house in accordance with EN 60950. The VPOL5A-12-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 7A. 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 For more information, please visit the product page. rev. page 7 of 12 date 08/2007 DESCRIPTION: point of load converter PART NUMBER: VPOL5A-12-SIP 7.2 Convection Requirements for Cooling To predict the ap proximate cooling needed for the module, refer to the Power De-rating curves in Figures 8 & 9 . 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 6 to ensure it does not exceed 110°C. Proper cooling can be verified by measuring the power module’s temperature at Q1-pin 6 as shown in Figure 7. W ind Tunnel 25.4(1.0) Bakelite Figure 7. Temperature Measurement Location for VPOL5A-12-SIP Power Module 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 76.2(3.0) based on measurements taken in a set-up as shown in Figure 6. Figures 8 & 9 represent the test data. Note that the airflow is parallel to the long axis of the module as shown in Figure 6 for the VPOL5A-12- Thermocuple Location for measuring ambient temperature and airflow 12.7(0.5) SIP. 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 SMT05 thermal data presented is based on measurements taken in a wind tunnel. The test setup shown Air flow 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 Fig 6. Note : Dimensions are in millimeters and (inches) Figure 6. Thermal Test Setup 20050 SW 112th Ave A . Tualatin, Oregon 97062 phone 503.612.2300 fa x 503.612.2382 For more information, please visit the product page. rev. DESCRIPTION: point of load converter PART NUMBER: VPOL5A-12-SIP 6.0 Output Current(A) 5.0 4.0 0LFM 3.0 100LFM 2.0 200LFM 1.0 0.0 0 10 20 30 40 50 60 70 80 90 100 Ambient Temperature( C)o Figure 2. Typical Power De-rating for 12V IN 3.3Vout NOTE 1. specific input & output derating curves available, please contact CUI INC for detail 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 page 8 of 12 date 08/2007 For more information, please visit the product page. rev. VPOL5A-12-SIP Vo=1.8V (Eff Vs Io) date 08/2007 VPOL5A-12-SIP Vo=1.5V (Eff Vs Io) 100% 95% 95% 90% 90% Efficincy (%) 100% Efficincy (%) 9 of 12 DESCRIPTION: point of load converter PART NUMBER: VPOL5A-12-SIP 85% 80% 75% 8.3V 12V 14V 70% 65% 85% 80% 75% 8.3V 12V 14V 70% 65% 60% 60% 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0 0.5 1 Current Load (A) 1.5 2 2.5 3 3.5 4 4.5 5 Current Load (A) VPOL5A-12-SIP Vo=1.2V (Eff Vs Io) VPOL5A-12-SIP Vo=0.75V (Eff Vs Io) 90% 95% 85% 90% 80% Efficincy (%) 100% Efficincy (%) page 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 Current Load (A) 3.5 4 4.5 5 0 0.5 1 1.5 2 2.5 3 Current Load (A) 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 3.5 4 4.5 5 For more information, please visit the product page. rev. The VPOL5A-12-SIP converters must be connected to a low AC source impedance. To avoid probl ems with loop stability source Line.reg = 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 VLL is the output voltage of minimum input voltage at full load. Current Meter Electrolytic capacitors should be avoided. Circuit as shown in Figure 10 A 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. VHL _ VLL x 100% VLL Where: VHL is the output voltage of maximum input voltage at full load. high capacitance, high ripple rating and low ESR (typical <100mohm). Power Supply +Vin + 47uF 10UF V VPOL5A-12-SIP CERAMIC +Vin 1uH 2*100uF Tantalum Figure 11. VPOL5A-12-SIP Test Setup VPOL5A-12-SIP 220uF ESR<0.1ohm Common Figure 10. 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 11. 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 CUI INC’s VPOL5A-12-SIP 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 x Io x 100% Vin x Iin 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: Load .reg = Common Voltage Meter L1 A +Vo +Sense Common To Oscilloscope ç= 08/2007 The value of line regulation is defined as: inductance should be low. Also, the input capacitors should be placed Supply date VFL is the output voltage at full load VNL is the output voltage at no load Where: 7.6 Input Capacitance at the Power Module + 10 of 12 DESCRIPTION: point of load converter PART NUMBER: VPOL5A-12-SIP Power page VFL _ VNL x 100% VNL 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 V Load For more information, please visit the product page. rev. page 11 of 12 date 08/2007 DESCRIPTION: point of load converter PART NUMBER: VPOL5A-12-SIP 7.8 VPOL5A-12-SIP Output Voltage Adustment. 7.9 Output Ripple and Noise Measurement The output Voltage of the VPOL5A-12-SIP can be adjusted in the range The test set-up for noise and ripple measurements is shown in Figure 0.75V to 5.0V by connecting a single resistor on the motherboard 13. a coaxial cable with a 50ohm termination was used to prevent (shown as R trim) in Figure 12. When Trim resistor is not connected the impedance mismatch reflections disturbing the noise readings at higher output voltage defaults to 0.75V frequencies. +Vin +Vin +Vo VPOL5A-12-SIP Trim R trim-up Common 1uF Ceramic R-Load Test Jack Common Common Figure 13. Output Voltage Ripple and Noise Measurement Set-Up Figure 12. Trim-up Voltage Setup The value of Rtrim-up defined as: 7.10 Output Capacitance CUI INC’s VPOL5A-12-SIP converters provide unconditional stability 10500 _ Rtrim = ( _ 1000 ) Vo 0.75 Where: 10uF Tant. R-Load VPOL5A-12-SIP Common +Vo Rtrim-up 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: 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. CUI INC’s converters are designed to work with load capacitance up-to 3,000uF. It is reco mmended that any additional capacitance, Maximum 3,000uF and low ESR, be connected Rtrim = ( 10500 _ 1000 ) _ 3 0.75 close to the point of load and outside the remote compensation point. Rtrim = 3118 ohm For various output values various resistors are calculated and provided in Table 3 for co nvenience. Vo,set (V) 0.75 1.2 1.5 1.8 2.0 2.5 3.3 5.0 Rtrim (Kohm) Open 22.33 13.00 9.00 7.40 5.00 3.12 1.47 Table 3 – Trim Resistor Values 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 For more information, please visit the product page. rev. DESCRIPTION: point of load converter PART NUMBER: VPOL5A-12-SIP 8. Mechanical Outline Diagrams 8.1 VPOL5A-12-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 VPOL5A-12-SIP 0.90(22.9) PIN CONNECTION 0.22(5.6)Max. Pin 1 2 3 4 5 0.400(10.16) 0.14(3.6) 0.100(2.54) 0.200(5.08) 0.700(17.78) 0.025(0.64) 0.025(0.64) FUNCTION 1 +Output 2 Trim 3 Common 4 +V Input 5 On/Off 0.19(4.7) 0.800(20.32) Figure 14 VPOL5A-12-SIP Mechanical Outline Diagram 20050 SW 112th Ave. Tualatin, Oregon 97062 phone 503.612.2300 fax 503.612.2382 page 12 of 12 date 08/2007