National Semiconductor Application Note 2022 Ricardo Capetillo August 12, 2010 Introduction Evaluation Board Design Concept The LMZ1050x SIMPLE SWITCHER® power module is a complete, easy-to-use DC-DC solution capable of driving up to 3A, 4A, or 5A load with exceptional power conversion efficiency, output voltage accuracy, line and load regulation. The LMZ1050x is available in an innovative package that enhances thermal performance and allows for hand or machine soldering. The LMZ1050x can accept an input voltage rail between 2.95V and 5.5V and deliver an adjustable and highly accurate output voltage as low as 0.8V. One megahertz fixed frequency PWM switching provides a predictable EMI characteristic. Two external compensation components can be adjusted to set the fastest response time, while allowing the option to use ceramic and/or electrolytic output capacitors. Externally programmable soft-start capacitor facilitates controlled startup. The LMZ1050x is a reliable and robust solution with the following features: lossless cycle-by-cycle peak current limit to protect for over current or short-circuit fault, thermal shutdown, input under-voltage lock-out, and pre-biased startup. The evaluation board is designed to demonstrate low conducted noise on the input and output lines, as seen in Figure 11 and Figure 14. Four input capacitors (Cin1 - C in4) and three output capacitors (Co1 - Co3) are populated for this purpose. All the input and output filter capacitors are not necessary to comply with radiation standards. For a circuit example that passes radiated emissions standards (EN55022, class B) please refer to Figure 19. Additionally, Cin5 is present to reduce the resonance of the input line produced by the inductance and resistance in the cables connecting the bench power supply to the evaluation board and the input capacitors. Board Specifications • • • • • • • • VIN = 2.95V to 5.5V VOUT = 2.5V (default output voltage setting, refer to Table 2 for other output settings) ±2.5% feedback voltage accuracy at 2.5V output (Including line and load regulation from TJ = -40°C to 125° C) ±1.63% feedback voltage accuracy over temperature IOUT = 0A to 3A, 4A, and 5A θJA = 20°C / W, θJC = 1.9°C / W Designed on four layers, the top and bottom layers are 1oz. copper and the two inner layers are 1/2 oz. copper weight Measures 2.25 in. x 2.25 in. (5.8 cm x 5.8 cm) and is 62mil (.062”) thick on a FR4 laminate LMZ1050x Evaluation Board LMZ1050x Evaluation Board Additional Component Footprints When the tracking feature of the LMZ1050x is used, remove the soft-start capacitor CSS and use a resistor divider on designators Rtrkb and Rtrkt. The ground and Vtrk post have been provided for easy connection. The LMZ1050x eval board incorporates a precision enable circuit which is pulled high by a 100 kΩ pull up resistor to VIN. This allows the user to pull low on the enable pin to ground. The top enable resistor is Rent and the bottom enable resistor is Renb. Refer to the Design Guideline and Operating Description section of the LMZ1050x data sheet for detailed design implementation. Select FPGAs specify input inrush currents for particular power-up sequences and others require sequencing rails to avoid start-up or latch-up problems. To prevent early turn-on of the LMZ1050x in systems with multiple power rails, precision enable and tracking are useful as the main input voltage rail rises at power-up. AN-2022 © 2010 National Semiconductor Corporation 301113 www.national.com AN-2022 Component Circuit Schematic 30111317 FIGURE 1. Component Schematic for Evaluation Board TABLE 1. Bill of Materials for Evaluation Board, VIN = 3.3V to 5V, VOUT = 2.5V Designator Description Case Size Manufacturer Manufacturer P/N Quantity U1 SIMPLE SWITCHER® TO-PMOD-7 National Semiconductor LMZ1050xTZ-ADJ 1 Cin1 1 µF, X7R, 16V 0805 TDK C2012X7R1C105K 1 Cin2, CO1 4.7 µF, X5R, 6.3V 0805 TDK C2012X5R0J475K 2 Cin3, CO2 22 µF, X5R, 16V 1210 TDK C3225X5R1C226M 2 Cin4 47 µF, X5R, 6.3V 1210 TDK C3225X5R0J476M 1 Cin5 220 µF, 10V, AL-Elec E Panasonic EEE1AA221AP 1 CO3 100 µF, X5R, 6.3V 1812 TDK C4532X5R0J107M 1 Rfbt 75 kΩ 0805 Vishay Dale CRCW080575K0FKEA 1 Rfbb 34.8 kΩ 0805 Vishay Dale CRCW080534K8FKEA 1 Rcomp 1.1 kΩ 0805 Vishay Dale CRCW08051K10FKEA 1 Ccomp 180 pF, ±5%, C0G, 50V 0603 TDK C1608C0G1H181J 1 Ren1 100 kΩ 0805 Vishay Dale CRCW0805100KFKEA 1 CSS 10 nF, ±5%, C0G, 50V 0805 TDK C2012C0G1H103J 1 TABLE 2. Output Voltage Setting (Rfbt = 75 kΩ) www.national.com VOUT Rfbb 3.3 V 23.7 kΩ 2.5 V 34.8 kΩ 1.8 V 59 kΩ 1.5 V 84.5 kΩ 1.2 V 150 kΩ 0.9 V 590 kΩ 2 AN-2022 Complete Circuit Schematic 30111324 FIGURE 2. Complete Evaluation Board Schematic 3 www.national.com AN-2022 Connection Diagram 30111315 FIGURE 3. Efficiency Measurement Setup 30111316 FIGURE 4. Output Voltage Ripple Measurement Setup Efficiency vs. Load Current LMZ10504 & LMZ10505, VOUT = 2.5V, TAMB = 25°C Efficiency vs. Load Current LMZ10503, VOUT = 2.5V, TAMB = 25°C 30111328 www.national.com 30111331 4 AN-2022 Performance Characteristics 30111329 30111330 FIGURE 5. Current Derating vs. Ambient Temperature LMZ10503, VIN = 5.0V, θJA = 20°C/W FIGURE 8. Current Derating vs. Ambient Temperature LMZ10503, VIN = 3.3V, θJA = 20°C/W 30111322 30111323 FIGURE 6. Current Derating vs. Ambient Temperature LMZ10504, VIN = 5.0V, θJA = 20°C/W FIGURE 9. Current Derating vs. Ambient Temperature LMZ10504, VIN = 3.3V, θJA = 20°C/W 30111332 30111333 FIGURE 7. Current Derating vs. Ambient Temperature LMZ10505, VIN = 5.0V, θJA = 20°C/W FIGURE 10. Current Derating vs. Ambient Temperature LMZ10505, VIN = 3.3V, θJA = 20°C/W 5 www.national.com AN-2022 30111318 30111320 FIGURE 11. Output Voltage Ripple VIN = 5V, VOUT = 2.5V, IOUT = 3A, 4A, & 5A LMZ10503 / LMZ10504 / LMZ10505 FIGURE 14. Output Voltage Ripple VIN = 3.3V, VOUT = 2.5V, IOUT = 3A, 4A, & 5A LMZ10503 / LMZ10504 / LMZ10505 30111337 30111336 FIGURE 12. Load Transient Response VIN = 5.0V, VOUT = 2.5V LMZ10503, IOUT = 400 mA to 2.7A, 20 MHz Bandwidth Limit FIGURE 15. Load Transient Response VIN = 3.3V, VOUT = 2.5V LMZ10503, IOUT = 300 mA to 2.7A, 20 MHz Bandwidth Limit 30111319 30111321 FIGURE 13. Load Transient Response VIN = 5V, VOUT = 2.5V LMZ10504, IOUT = 400 mA to 3.6A, 20 MHz Bandwidth Limit www.national.com FIGURE 16. Load Transient Response VIN = 3.3V, VOUT = 2.5V LMZ10504, IOUT = 400 mA to 3.6A, 20 MHz Bandwidth Limit 6 AN-2022 30111334 30111335 FIGURE 18. Load Transient Response VIN = 3.3V, VOUT = 2.5V LMZ10505, IOUT = 500 mA to 4.5A, 20 MHz Bandwidth Limit FIGURE 17. Load Transient Response VIN = 5.0V, VOUT = 2.5V LMZ10505, IOUT = 500 mA to 4.5A, 20 MHz Bandwidth Limit 7 www.national.com AN-2022 Circuit Example: Complies with EN55022 Class B Radiated Emissions 30111325 FIGURE 19. Component Schematic, VIN = 5V, VOUT = 2.5V, Complies with EN55022 Class B Radiated Emissions TABLE 3. Bill of Materials Designator Description Case Size Manufacturer Manufacturer P/N Quantity U1 SIMPLE SWITCHER® TO-PMOD-7 National Semiconductor LMZ10503/4/05TZ-ADJ 1 Cin1 1 µF, X7R, 16V 0805 TDK C2012X7R1C105K 1 Cin2 4.7 µF, X5R, 6.3V 0805 TDK C2012X5R0J475K 1 Cin3 47 µF, X5R, 6.3V 1210 TDK C3225X5R0J476M 1 CO1 100 µF, X5R, 6.3V 1812 TDK C4532X5R0J107M 1 Rfbt 75 kΩ 0805 Vishay Dale CRCW080575K0FKEA 1 Rfbb 34.8 kΩ 0805 Vishay Dale CRCW080534K8FKEA 1 Rcomp 1.1 kΩ 0805 Vishay Dale CRCW08051K10FKEA 1 Ccomp 180 pF, ±5%, C0G, 50V 0603 TDK C1608C0G1H181J 1 CSS 10 nF, ±5%, C0G, 50V 0805 TDK C2012C0G1H103J 1 30111338 30111326 FIGURE 20. Radiated Emissions (EN55022, Class B) VIN = 5V, VOUT = 2.5V, IOUT = 3A Tested on LMZ10503 Evaluation Board www.national.com FIGURE 21. Radiated Emissions (EN55022, Class B) VIN = 5V, VOUT = 2.5V, IOUT = 4A Tested on LMZ10504 Evaluation Board 8 AN-2022 30111327 FIGURE 22. Radiated Emissions (EN55022, Class B) VIN = 5V, VOUT = 2.5V, IOUT = 5A Tested on LMZ10505 Evaluation Board 9 www.national.com AN-2022 PCB Layout Diagram 30111307 FIGURE 23. Top Layer 30111308 FIGURE 24. Internal Layer I (Ground) www.national.com 10 AN-2022 30111311 FIGURE 25. Internal Layer II (Ground) 30111313 FIGURE 26. Bottom Layer 11 www.national.com LMZ1050x Evaluation Board For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com Products Design Support Amplifiers www.national.com/amplifiers WEBENCH® Tools www.national.com/webench Audio www.national.com/audio App Notes www.national.com/appnotes Clock and Timing www.national.com/timing Reference Designs www.national.com/refdesigns Data Converters www.national.com/adc Samples www.national.com/samples Interface www.national.com/interface Eval Boards www.national.com/evalboards LVDS www.national.com/lvds Packaging www.national.com/packaging Power Management www.national.com/power Green Compliance www.national.com/quality/green Switching Regulators www.national.com/switchers Distributors www.national.com/contacts LDOs www.national.com/ldo Quality and Reliability www.national.com/quality LED Lighting www.national.com/led Feedback/Support www.national.com/feedback Voltage References www.national.com/vref Design Made Easy www.national.com/easy www.national.com/powerwise Applications & Markets www.national.com/solutions Mil/Aero www.national.com/milaero PowerWise® Solutions Serial Digital Interface (SDI) www.national.com/sdi Temperature Sensors www.national.com/tempsensors SolarMagic™ www.national.com/solarmagic PLL/VCO www.national.com/wireless www.national.com/training PowerWise® Design University THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. NATIONAL MAKES NO REPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY OR COMPLETENESS OF THE CONTENTS OF THIS PUBLICATION AND RESERVES THE RIGHT TO MAKE CHANGES TO SPECIFICATIONS AND PRODUCT DESCRIPTIONS AT ANY TIME WITHOUT NOTICE. NO LICENSE, WHETHER EXPRESS, IMPLIED, ARISING BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS DOCUMENT. TESTING AND OTHER QUALITY CONTROLS ARE USED TO THE EXTENT NATIONAL DEEMS NECESSARY TO SUPPORT NATIONAL’S PRODUCT WARRANTY. EXCEPT WHERE MANDATED BY GOVERNMENT REQUIREMENTS, TESTING OF ALL PARAMETERS OF EACH PRODUCT IS NOT NECESSARILY PERFORMED. NATIONAL ASSUMES NO LIABILITY FOR APPLICATIONS ASSISTANCE OR BUYER PRODUCT DESIGN. BUYERS ARE RESPONSIBLE FOR THEIR PRODUCTS AND APPLICATIONS USING NATIONAL COMPONENTS. PRIOR TO USING OR DISTRIBUTING ANY PRODUCTS THAT INCLUDE NATIONAL COMPONENTS, BUYERS SHOULD PROVIDE ADEQUATE DESIGN, TESTING AND OPERATING SAFEGUARDS. EXCEPT AS PROVIDED IN NATIONAL’S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, NATIONAL ASSUMES NO LIABILITY WHATSOEVER, AND NATIONAL DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY RELATING TO THE SALE AND/OR USE OF NATIONAL PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS PRIOR WRITTEN APPROVAL OF THE CHIEF EXECUTIVE OFFICER AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: Life support devices or systems are devices which (a) are intended for surgical implant into the body, or (b) support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in a significant injury to the user. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system or to affect its safety or effectiveness. National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other brand or product names may be trademarks or registered trademarks of their respective holders. AN-2022 Copyright© 2010 National Semiconductor Corporation For the most current product information visit us at www.national.com National Semiconductor Americas Technical Support Center Email: [email protected] Tel: 1-800-272-9959 www.national.com National Semiconductor Europe Technical Support Center Email: [email protected] National Semiconductor Asia Pacific Technical Support Center Email: [email protected] National Semiconductor Japan Technical Support Center Email: [email protected]