Integrated High-current Power Stage Offers Small Footprint for Processor Loads
LTC7051-1, with integrated drivers and switches, powers the next generation of high-current processors.
The recently released LTC7051-1 from Analog Devices is a fully integrated power stage that incorporates into a single package the high-power MOSFET switches and drivers needed for a high current step-down DC/DC converter. When paired with a suitable switching regulator controller (LTC3861, etc.), power inductor and other passives, it forms the basis of a complete and compact, step-down converter solution well-suited for high current server and networking processor applications.
Integrating Power Stage for a Point of Load Converter
The integrated FETs can handle peak currents up to 140 A and continuous loads up to 65 A. The LTC7051-1 accommodates a nominal 12 V input (7 V - 14 V) and comes in a 5 mm x 8 mm, 42L LQFN package with a height profile of 0.95 mm. The LTC7051-1 is a single channel variant of the LTC7050 and expands the nominal input voltage range from 14 V to 16 V.
LTC7051-1 Integrated Power Stage Block Diagram. Image used courtesy of Analog Devices
LTC7051-1 Typical Application Circuit. Image used courtesy of Analog Devices
Benefits of Driver and MOSFET Modules
The LTC7051-1 is a DrMOS (Driver and MOSFET) module. For several reasons, higher levels of component integration are an important trend in power electronics.
Smaller circuit footprints with reduced component counts enable more compact layouts, particularly important for end applications with size constraints. Higher component integration also translates to lower system costs. Fewer components in a design simplify supply chain management for purchasers and component engineers. A lower part count also reduces manufacturing costs since fewer components need to be placed on the PCB, allowing for higher throughput. The smaller PCB area also translates to a direct cost saving, with the PCB often being one of the more expensive items in a system BOM. Module integration can also lead to better performance in power designs, allowing for more compact layouts that are less susceptible to the effects of unwanted parasitics.
However, it’s fair to note that an integrated module like the LTC7051-1 may not always be the best choice for an application. Sometimes the features or performance specifications of the integrated module may not be suitable for the design priorities of a particular circuit design. In these cases, a discrete solution (FETs, drivers, etc.) may be a better choice, despite the sacrifice in size, simplicity and cost.
The LTC7051-1 is part of the SlientMOS family of integrated power stage modules from Analog Devices (formerly Linear Technology) that incorporates Silent Switcher 2 technology. In traditional buck conversion designs, external filter capacitors are typically at the input of the FET drivers to help with noise filtering.
However, the junction between these capacitors and the power FET can form parasitic inductance loops that create large switching node spikes, or ringing, during operation.
With SilentMOS, the LTC7051-1 integrates these input capacitors into the module, significantly reducing the size of the parasitic loops and minimizing switching spikes. Reducing switching spikes improves the converter's efficiency and reliability, since switching FETs are no longer repeatedly subject to high voltage spikes.
Also, the power FETs and drivers in the LTC7051-1 are integrated on the same silicon die and co-packaged with the other passive components. As a monolithic die, the need for bonding wires between the FETs and drivers is eliminated, reducing the associated parasitics and allowing for better parametric performance of the module.
SilentMOS Technology integrates the driver input filter capacitor. Image used courtesy of Analog Devices
The value of high-level component integration to system designs is evident. As the demands for performance, cost and size continue to expand, it’s a safe bet that we will continue to see even more solutions with ever-increasing levels of component integration.
Featured image used courtesy of Adobe Stock