1 Introduction

The use of higher voltage rails and inputs is an increasing trend across markets such as:

• 48V Automotive systems - Hybrid electric vehicles (HEV) and on board charging
• 48V Enterprise and Communications - Data-centers and remote radio units
• 24V rails in Industrial - Factory automation, robotics and building automation

Large voltage transients are a common challenge in these applications requiring some 24V rail applications to use devices rated for 65V. Similarly, 48V automotive systems need to handle cold-crank voltage transients in the range of 65V to 80V. Typically for Wide-Vin, high output current designs, a buck controller with external MOSFETs is a standard choice.

New innovations in IC design, packaging and manufacturing allow for the creation of power dense, high current, high-voltage converters. These devices also have the ability to multi-phase allowing them to reach output currents that typically a controller solution could only achieve. Converter based designs offer many benefits over classical controller designs but also share some tradeoffs that can be highlighted in this report. Below is a high-level bullet point list of each device’s value proposition and summarized in Table 1-1.

Buck controller designs feature a PWM controller IC that control external MOSFETs. These designs require good and careful layout design to minimize large parasitic loops created between the controller IC, MOSFETs and key passives such as the input and output capacitors and the inductor. With good design considerations a buck controller design provides the following value proposition:

• More design flexibility and optimization to design specifications
• More component optimization for efficiency and thermal performance
• Can achieve the lowest bill-of-material (BoM) cost

Buck converters feature a controller with one or more integrated power FETs. Some of the design challenges of a controller design are greatly mitigated with a converter. For example, with integrated FETs critical parasitic loops are minimized resulting in lower EMI designs to pass stringent EMI requirements easier. A buck converter design provides the following value proposition:

• Component integration simplifies component sourcing, reduces customer BoM and enables smaller design sizes
• Greatly reduces time and cost to market by reducing power-stage design time
• Minimized parasitic loops result in lower EMI emissions allowing for smaller and lower cost EMI filters