V I S H AY I N T E R T E C H N O L O G Y, I N C . RECTIFIERS TMBS ® Guide to Switchmode Power Supply Applications TABLE OF CONTENTS Introduction................................................................................................................................................. 2 Package Summary Details.......................................................................................................................... 2 Applications................................................................................................................................................. 2 Output Rectifiers in SMPS.......................................................................................................................... 3 Notebook Adaptors..................................................................................................................................... 3 Printer +32 V Adaptors................................................................................................................................ 3 Desktop SMPS............................................................................................................................................ 3 Telecom AC/DC Power Supplies................................................................................................................. 4 Telecom DC Systems Isolation.................................................................................................................... 4 Distributed Telecom Power Systems.......................................................................................................... 4 Notebook Polarity Protection...................................................................................................................... 5 OR-ing Diode Applications.......................................................................................................................... 5 Conclusion.................................................................................................................................................. 5 A WORLD OF SOLUTIONS Application Guide 1/5 THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000 VMN-PL0468-1507 www.vishay.com V I S H AY I N T E R T E C H N O L O G Y, I N C . RECTIFIERS TMBS ® Guide to Switchmode Power Supply Applications Introduction Vishay Semiconductors is the world´s leading supplier of TMBS® Trench MOS Barrier Schottky rectifiers, offering a number of low-VF, high-speed devices from 45 V to 200 V. These TMBS rectifiers are backed by a vertically integrated company with over 50 years of experience in rectifier die fabrication and packaging. This guide serves to provide product recommendations for device selection in key applications. Packaging Summary Table The majority of applications we will cover use the packages shown in the table below. As demonstrated, there are a wide variety of leaded and surface-mount devices available. Power Packages Surface Mount 45 V TO-220, ITO-220,TO-262 SMPC, SlimSMA, TO-263 60 V TO-220, ITO-220,TO-262 SMP, SMA, SMB, TO-263 80 V TO-220, ITO-220,TO-262 100 V TO-220, ITO-220, TO-262, TO-3PW SMPC,SMA, SMB, TO-263 120 V TO-220, ITO-220,TO-262 SMPC, TO-263 150 V TO-220, ITO-220,TO-262 TO-263 170 V TO-220, TO-3PW TO-263 200 V TO-220, ITO-220,TO-262, TO-3PW SMB, SMC, TO-263 Axial P600, DO-201AD DO-201AD, DO-15,DO-41 Applications There are literally thousands of applications that use rectifiers. This application note will cover eight key switchmode power supply (SMPS) applications for TMBS devices, including: • Output rectifiers in tablet PC chargers, notebook and printer adaptors, desktop power supplies, LCD TVs, and telecom DC/DC converters and AC/DC power supplies • Telecom DC input/output OR-ing diodes and blocking diodes Application Guide 2/5 THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000 VMN-PL0468-1507 www.vishay.com V I S H AY I N T E R T E C H N O L O G Y, I N C . RECTIFIERS TMBS ® Guide to Switchmode Power Supply Applications Output Rectifiers in SMPS Vishay Semiconductors is the leader in using Trench MOS technology to improve Schottky rectifier performance, thereby increasing SMPS efficiency to meet power saving requirements. The company’s TMBS rectifiers can shorten the design cycle, and improve reliability and lower costs over synchronous rectifiers by reducing the need for extra control circuitry. Optimizing SMPS designs, TMBS devices provide lower VF with a good reverse leakage current (IR) trade-off to meet the requirements of different application conditions. Notebook Adaptors Most notebook adaptors use fly-back topology, as shown in the circuit to the right. In the diagram, D2 is the output rectifier of the adaptor. An R-type 100 V or 120 V TMBS rectifier with excellent VF can provide a fly-back converter for higher performance. An M-type 120 V TMBS device can improve the VF of a conventional planar Schottky rectifier and maintain a low leakage current for the hightemperature requirements in notebook adaptors. The TO-220 and ITO-220 packages are most often utilized in notebook applications. A 120 V TMBS rectifier in an SMPC package is a good solution in applications requiring a slim adaptor, such as tablet and smart phone chargers, which also use fly-back topology. L- and R-type 45 V TMBS devices in SMPC packages can provide the low profile and high performance required in these applications. Printer +32 V Adaptors +32 V is the DC output voltage for multifunction inkjet printers. Since the output current is small, 200 V TO-220, ITO-220, or axial TMBS rectifiers provide simple, low-cost solutions for this application. Desktop SMPS Desktop SMPS often use 60 V to 100 V Schottky rectifiers as +12 V output rectifiers. 60 V to 100 V TMBS rectifiers can provide low VF to reduce power loss and increase efficiency. 45 V Schottky devices are ideal for +5 V and +3.3 V output rectifiers. With their low VF, R- and L-type 45 V TMBS provide good desktop SMPS solutions to meet the 80+ iron and bronze standards of installed cooling fans. To lower costs and shorten the design cycle, it is helpful for SMPS designers to use the most popular forward converter topologies. To the right is a basic two-switch forward converter topology circuit, where D1 to D6 are the output rectifiers. TMBS devices can be used to easily achieve the 80+ bronze standard. Application Guide 3/5 THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000 VMN-PL0468-1507 www.vishay.com V I S H AY I N T E R T E C H N O L O G Y, I N C . RECTIFIERS TMBS ® Guide to Switchmode Power Supply Applications Telecom AC/DC Power Supplies Since telecom AC/DC power supplies feature outputs from 24 VDC to 72 VDC, 150 V, 170 V, and 200 V TMBS rectifiers are suitable solutions for these high-power, high-reliability applications that often utilize full-bridge softswitching technology. In the diagram, D1 and D2 are the output rectifiers of a telecom AC/DC SMPS, for which TMBS rectifiers are ideal solutions for meeting high-performance and high-reliability requirements. Telecom DC Systems Isolation Blocking diodes are used in telecom systems to isolate DC power input by AC/DC power supplies or battery banks. With their low VF characteristic, 80 V to 200 V TMBS rectifiers provide good blocking for DC power input systems. Distributed Telecom Power System Isolation Distributed telecom power systems often use point-of-load (POL) converters to provide the specified DC power to the POL, as shown in the illustration. Due to system space limitations, converters with higher switching frequencies must be used to increase the power density and reduce the converter volume. For this application, TMBS rectifiers provide excellent switching performance and lower conduction losses than conventional Schottky or ultrafast rectifiers. A comparison of the VF and Trr of the three device types is shown below. As demonstrated, TMBS rectifiers are the best solution for this highperformance and high-reliability application. Switching of 200 V Schottky (IF = 6 A, di/dt = -200 A/µS, VR = 200 V, 10 %, TA = 100 °C Planar Schottky SBR Schottky 200 V TMBS JF (A/cm2) TMBS VF is the best VF (V) TMBS Application Guide Planar Schottky Ultrafast 1 TA = 125 °C Ultrafast 2 Ultrafast 3 4/5 THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000 VMN-PL0468-1507 www.vishay.com V I S H AY I N T E R T E C H N O L O G Y, I N C . RECTIFIERS TMBS ® Guide to Switchmode Power Supply Applications Notebook Polarity Protection Power adaptors for notebook computers use blocking diodes for DC input polarity protection. In the illustration, D1 is the polarity protection rectifier. A 45 V SMPC TMBS rectifier provides the low VF, low profile, and good heat dissipation required in notebook designs. OR-ing Diode Applications OR-ing diodes are simple solutions for multiinput or redundant power system in some high-end or high-reliability applications, as demonstrated in the illustration to the right. TMBS rectifiers can provide low-power-loss solutions for OR-ing diode applications. Conclusion TMBS rectifiers improve on the weak points in the designs of conventional planar devices to provide better voltage drop and switching performance. They also provide better VF than ultrafast rectifiers in 200 V applications. TMBS rectifiers are ideal solutions for meeting power saving requirements in a variety of applications across the world market. Application Guide 5/5 THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000 VMN-PL0468-1507 www.vishay.com