Product Overview SEMTECH POWER MANAGEMENT EcoSpeed® DC-DC Converters: Best-in-Class Performance for Dynamic Point-of-Load Applications Unique buck converter platform provides ultra-fast transient response and high efficiency across the entire load range. Description The EcoSpeed® converter platform incorporates Semtech’s patented(1) adaptive on-time (AOT) control architecture to deliver: • Very high efficiency across the entire load range • Ultra-fast transient response • Easy-to-use, small and highly integrated DC-DC converters This unique architecture offers the benefits of conventional converter topologies with optimal tradeoffs for best-in-class performance in next-generation dynamic point-of-load applications. These buck converters are inherently well suited to implement a reduced frequency power-save (PSAVE) mode for up to 95% peak efficiency in light load conditions, with the option of ultrasonic PSAVE mode for applications requiring no audible resonance during power save. Semtech’s EcoSpeed converters minimize output capacitance, eliminate the need for external compensation components and enable the use of ceramic input/output capacitors to provide a simple, space-saving and low-cost solution. Key Features • Patented adaptive on-time control architecture - Ultra-fast transient response - Pseudo-fixed switching frequency typically ±15% accuracy - Programmable switching frequency: 200kHz to 1MHz - Very high efficiency across the entire load range - No external compensation components required - Up to 95% peak standby efficiency • Power save (PSAVE) maximizes light load efficiency • Wide input voltage range: 3V to 28V • Output current range: 1A to 30A • SmartDrive™ technology reduces EMI • Low profile MLPQ and MLPD packages VOUT = 0.50V to 5.25V, IOUT up to 10A BST 3 to 28V VIN VOUT LX 5V ILIM VDD SC417 FB Can be VLDO if VIN > 4.5V VOUT Enable, PSAVE Select VLDO Enable EN/PSV PGOOD VLDO ENL VLDO = 0.75V to 5.25V, ILDO up to 150mA FBL TON (1) U.S. Patent No. 7,714,547 VOUT Power Good PGND AGND W W W .SE MTE C H .C OM Converters Product Overview EcoSpeed DC-DC Converter Product Portfolio Orderable Part# Type On-Chip LDO? VIN Range VDD Range VOUT Range IOUT PGOOD Enable (max) SC171 Regulator No 3 - 5.5V 3 - 5.5V 0.75 to 95% VIN 1A Yes SC172 Regulator No 3 - 5.5V 3 - 5.5V 0.75 to 95% VIN 2A Yes PSAVE Package Yes Ultrasonic MLPD-10 (3 x 3 x 1mm) Yes Ultrasonic MLPD-10 (3 x 3 x 1mm) SC173 Regulator No 3 - 5.5V 3 - 5.5V 0.75 to 95% VIN 3A Yes Yes Ultrasonic MLPD-10 (3 x 3 x 1mm) SC173A Regulator No 3 - 5.5V 3 - 5.5V 0.75 to 95% VIN 3A Yes Yes Regular MLPD-10 (3 x 3 x 1mm) SC174 Regulator No 3 - 5.5V 3 - 5.5V 0.75 to 95% VIN 4A Yes Yes Ultrasonic MLPD-10 (3 x 3 x 1mm) SC401B Regulator Yes 3 - 17V 3 - 5.5V 0.6 to 5.5V 15A Yes Yes Ultrasonic MLPQ-32 (5 x 5 x 1mm) SC402B Regulator Yes 3 - 28V 3 - 5.5V 0.6 to 5.5V 10A Yes Yes Ultrasonic MLPQ-32 (5 x 5 x 1mm) SC403B Regulator Yes 3 - 28V 3 - 5.5V 0.6 to 5.5V 6A Yes Yes Ultrasonic MLPQ-32 (5 x 5 x 1mm) SC410 Regulator Yes 5.5V to 24V n/a 0.75 to 7.5V 3A Yes Yes Ultrasonic MLPD-10 (3 x 3 x 1mm) SC414 Regulator Yes 3 - 28V 3 - 5.5V 0.75 to 5.5V 6A Yes Yes Ultrasonic MLPQ-28 (4 x 4 x 1mm) MLPQ-32 (5 x 5 x 1.0mm) SC417 Regulator Yes 3 - 28V 4.5 - 5.5V 0.5 to 5.5V 10A Yes Yes Ultrasonic MLPQ-32 (5 x 5 x 1mm) SC418 PWM Controller Yes 3 - 28V 3 - 5.5V 0.5 to 5.5V 30A* Yes Yes Prog. Ultrasonic or Regular MLPQ-UT-20 (3 x 3 x 0.6mm) SC419 PWM Controller No 3 - 28V 4.5 - 5.5V 0.5 to 5.5V 30A* Yes Yes Prog. Ultrasonic or Regular MLPQ-UT-20 (3 x 3 x 0.6mm) SC424 Regulator Yes 3 - 28V 3 - 5.5V 0.75 to 5.5V 6A Yes Yes Regular MLPQ-28 (4 x 4 x 1mm) SC427 Regulator Yes 3 - 28V 4.5 - 5.5V 0.5 to 5.5V 10A Yes Yes Regular MLPQ-32 (5 x 5 x 1mm) SC493 I2C Controller Yes Prog. Ultrasonic or Regular MLPQ-UT-20 (3 x 3 x 0.6mm) No 3 - 28V 3 - 5.5V 0.5 to 5.0V 30A* Yes * External FET drive EcoSpeed DC-DC Converter Block Diagrams Reference Controller & Regulator Reference Control Soft Start On-Time Generator Soft Start Gate Drive Control On-Time Generator Zero-Cross Valley Current Limit Valley Current Limit Controller Excellent Efficiency Even at Light Loads Efficiency vs Load (SC417) PSAVE Mode 100% PWM Mode VIN = 12V FSW = 300kHz 95% 0.75V Vout 0.9V Vout 1.3V Vout 1.5V Vout 1.8V Vout 2.5V Vout 3.3V Vout 5V Vout 90% EFF (%) Gate Drive Control Zero-Cross Regulator High Efficiency Control 85% 80% 75% 70% 0.1 1 IOUT (A) 10 W W W .SE MTE C H .C OM -2- Converters Product Overview Excellent Transient Response Load Transient Response — Load Falling (SC174) Load Transient Response — Load Rising (SC174) Programmable Pseudo-Fixed Frequency Semtech’s EcoSpeed converters offer a programmable frequency from 200kHz to 1MHz, which is maintained with an accuracy of typically ±15% – similar to many conventional fixed frequency implementations. SmartDrive™ Technology SmartDrive technology is Semtech’s approach to implementing the converter gate drive circuitry to reduce EMI. EMI is usually a problem during the turn-on of the high-side FET in a buck converter power stage. This is due to the reverse recovery charge current, which results in a high spike from the body diode of the low-side FET. To avoid this, all Semtech EcoSpeed products incorporate a two-step, high-side FET turn-on Switching Frequency (SC417) 500 Switching Frequency (kHz) Many applications are sensitive to DC-DC converter frequency and require a fixed frequency to ensure that inductor-radiated EMI is in a known and acceptable band. Conventional current mode and voltage mode conversion architectures have a fixed frequency with an accuracy typically up to ±20%. Other topologies, including simple hysteretic, or the fast-responding constant on-time mode, generally have frequencies that are unpredictable with limited ability to control the extreme variations in frequency due to input and output conditions. Tightly Controlled Programmable Frequency 450 ±15% 400 350 300 250 200 150 100 50 0 10 21 32 43 5 4 6 5 7 6 8 7 9 8 10 9 11 10 12 11 Load Current (A) Frequency Programmable from 200kHz to 1MHz SmartDrive™ Reduces EMI scheme. The first step is a weak turn-on to allow the reverse recovery current to pass through. The second step is a full turn-on to quickly transition the inductor phase node to VIN with minimal power loss. This approach reduces EMI, while maintaining high efficiency. W W W .SE MTE C H .C OM -3- Converters Product Overview PSAVE: Low Standby Power and Fast Wake-Up Response Power efficiency in standby mode is increasingly important for today’s “green” initiatives. However, most electronic products also require fast “wake-up” capability, which demands fast recovery from low-power standby to full-power operation. To solve this problem, EcoSpeed DC-DC converters offer a power-save (PSAVE) mode, which lowers the switching frequency to cater to the light load requirement during standby. This improves efficiency during light loads by reducing the switching losses associated with the power FET gate charge. Since the EcoSpeed architecture responds on a cycle-by-cycle basis, when the load flips from light to full conditions, the converter can quickly exit PSAVE mode providing fast wake-up response time. Several EcoSpeed DC-DC converters also offer an ultrasonic PSAVE (UPSAVE) feature, which ensures that the device switching frequency stays above a 25kHz threshold to eliminate audible resonance. Additionally, all EcoSpeed devices offer smart PSAVE, which is designed to prevent the output voltage from floating higher than 10% by turning on the low-side power FET and draining any excess charge from COUT. This ensures that in light load conditions the converter does not hit a false OVP. How Do EcoSpeed Converters Compare to Conventional Architectures? The EcoSpeed buck converter platform incorporates the best of current mode, voltage mode and constant on-time control topologies, with minimal tradeoffs. The key to these performance advantages is Semtech’s patent-pending adaptive on-time control (AOT) architecture, which uses an advanced control loop to dynamically adjust the on-time based on input voltage and output voltage. This results in a pseudo-fixed frequency operation and very predictable EMI, comparable to existing voltage and current mode topologies and better than constant on-time architectures. Unlike conventional voltage and current mode control topologies, the AOT architecture eliminates the need for external error amplifiers, simplifying design and reducing component count. Additionally, Semtech’s AOT architecture works with all capacitor chemistries for design flexibility and optimized BOM costs. EcoSpeed Architecture Provides Optimal Trade-Offs Function Current Mode Control Voltage Mode Control Constant On-Time EcoSpeed® Adaptive On-Time Line Regulation Excellent Good Excellent Excellent Load Regulation Excellent Moderate Excellent Excellent External Compensation Single Pole Double Pole None None Stable Operation with Wide Range of Load Capacitance Yes No No Yes Switching Frequency Constant Constant Variable Pseudo-Constant Simple, Cost-Effective Architecture No No Yes Yes Loop Response Fast Slow Ultra-Fast Ultra-Fast COUT Flexible Somewhat Limited Somewhat limited Flexible PSAVE Not Inherent Not Inherent Inherent Inherent PCB Layout Sensitivity Yes No Yes Yes Semtech, the Semtech logo and EcoSpeed are registered marks of Semtech Corporation and SmartDrive™ is a trademark of Semtech Corporation. Semtech reserves the right to make changes to, or discontinue any products described in this document without further notice. I2C and the I2C bus are trademarks of NXP B.V. Semtech makes no warranty, representation or guarantee, express or implied, regarding the suitability of its products for any particular purpose. ©2011 Semtech Corporation. All rights reserved. EcoSpeedPB-0411 W W W .SE MTE C H .C OM -4-