Dc-Dc Intermediate Bus Converters


In this presentation, we will begin with an overview of the intermediate bus power architecture. Following the overview, we will introduce CUI's family of advanced intermediate bus dc-dc converters featuring an optional PMBus digital interface, including a description of the available features, configurations, and advantages versus other products on the market.


  • Highlight the need for an intermediate bus architecture
  • Introduce the NEB and NQB intermediate bus series
  • Describe the series' key features and specifications
  • Introduce the Architects of Modern Power consortium
  • Highlight the optional digital interface
  • List target applications

An Interconnected World Creates Hardware Challenges

The increasing global demand for online services, data processing and storage capability has led to exceptional growth in cloud computing, which in turn has meant the setup and expansion of huge data centres across the world. While cloud computing is highly efficient in terms of reducing computing hardware, the transfer of this computing power into a centralized location creates engineering challenges as well as concerns over the direct environmental impact of these huge data processing factories that drive the cloud. Data centre operators continue to seek significant reductions in their direct environmental footprint, and a key focus for them has become the reduction of energy usage at the board level. Because of this, efficiency, thermal performance, and telemetry are becoming increasingly important factors in the design of next generation networking applications.

Intermediate Bus Architecture

In many networking and high-end computing equipment, the preferred power delivery method is through a 48V distributed power system. Intermediate bus converters play a crucial role in distributed power systems because isolation within the system is a basic requirement. The intermediate bus architecture is a form of a distributed power system that seeks to limit this isolation function to a single conversion point, increasing overall system efficiency. CUI's Dc-Dc intermediate bus converter series has been designed to maximize performance at this crucial point in the power architecture.

Flattening the Efficiency Curve

The NEB series and NQB series incorporate a 32-bit ARM-based microcontroller with power-optimizing firmware designed to maximize and flatten the efficiency curve, providing peak performance across a much wider range of loading conditions when compared to intermediate bus converters currently on the market. With typical efficiencies as high as 96.4% and optimized efficiency from 20% to 100% load, the modules are ideal in applications where loading conditions can vary greatly, including next-generation Information and Communication Technology (ICT) equipment.

AMP Group Compliant

CUI's NEB and NQB series are pin and function compatible with the Architects of Modern Power (AMP) product standards. The AMP Group is a power consortium formed by CUI, Ericsson Power Modules, and Murata in order to facilitate the development and marketing of advanced power products for distributed power architectures. AMP Group members have agreed upon common mechanical and electrical specifications for their products, including standardization of monitoring, control and communications functions, as well as common configuration files for plug-and-play interoperability between modules from each firm. CUI's NEB series is compliant with the AMP Group's ABC-ebAMP standard, while CUI's NQB series is compliant with the AMP Group's ABC-qbAMP standard.

Advanced Bus Converter Standards

  • Power Range: 264 to 300 W
  • Digital and analog configurations
  • Matching feature sets
  • Compatible configuration files
  • Power Range: 420 to 468 W
  • Digital and analog configurations
  • Matching feature sets
  • Compatible configuration files

Industry Standard Footprint

Both families are available in an industry standard 5-pin package, addressing the needs of analog distributed bus power systems. The standard configuration also provides a high efficiency drop-in solution for existing applications utilizing 1/8 brick and 1/4 brick intermediate bus converters.

Optional Digital Interface

Both the NEB and NQB series provide a digital interface that is PMBus 1.2 compliant, allowing customers to configure and store a range of parameters via a USER_STORE memory block. Designers are able to set a number of protection features and configurable parameters.

Features include:

  • Configurable start/stop
  • Configurable precision delay and ramp-up
  • Voltage/current/temperature monitoring
  • Configurable output voltage
  • Configurable fault response


The NEB and NQB series are ideal for a wide range of Information and Communication Technology (ICT) equipment:

  • Enterprise servers
  • Mainframes
  • Storage equipment
  • Telecom base stations
  • Video Switching
  • Access networks
  • Network switches

Product Benefits

CUI's NEB and NQB series are fully regulated intermediate bus dc-dc converters featuring typical efficiencies as high as 96.4%. The dc-dc modules are pin and function compatible with the Architects of Modern Power , enabling original equipment makers (OEMs) to address interoperability challenges, reduce time to market, and decrease supply chain risk for these leading-edge power modules. Additional series highlights include 2250 V dc isolation, a +/- 2% output voltage tolerance across the entire input voltage range and output load current range, along with UL 60950-1 safety approvals.

  • 96.4% typical efficiency at half load
  • Fully regulated
  • 2250 Vdc isolation
  • +/- 2% output voltage tolerance
  • UL 60950-1 approved
  • Pin and function compatible with Architects of Modern Power™ product standards

CUI's Intermediate Bus Series Options

  • 5-pin industry standard package tih or without digital PMBus interface.
  • Baseplate for improved thermal performance.
  • Droop load sharing with 10% current share accuracy for higher power applications.

NEB 1/8 Brick Series

CUI's NEB series is housed in an industry standard 1/8 brick package, ranging in power from 264 W to 300 W depending on the input voltage range. All models are preset to output 12 volts dc, with an adjustable output available from 6.9 to 13.2 volts dc. The output voltage is user-configurable for models with the optional digital interface. Analog versions can be preset at the factory if an alternate output voltage is required.

Series Power (W) Input Range (Vdc) Preset Output Voltage (Vdc) Output Voltage Range (Vdc) Digital Interface
NEB-264D 264 36~75 12 6.9~13.2
NEB-264N 264 36~75 12 6.9~13.2
NEB-300D 300 40~60 12 6.9~13.2
NEB-300N 300 40~60 12 6.9~13.2

NQB 1/4 Brick Series

The NQB series is housed in an industry standard 1/4 brick package, ranging in power from 420 W to 468 W depending on the input range. Like the NEB family, all models are preset to output 12 volts dc with an available output voltage range of 4.0~13.2 volts dc. Available footprints include options for an industry 5-pin configuration or an added digital interface.

Series Power (W) Input Range (Vdc) Preset Output Voltage (Vdc) Output Voltage Range (Vdc) Digital Interface
NQB-420D 420 36~75 12 4.0~13.2
NQB-420N 420 36~75 12 4.0~13.2
NQB-468D 468 40~60 12 4.0~13.2
NQB-468N 468 40~60 12 4.0~13.2


As the world connects, engineers will look to drive inefficiency out of every point along the power chain all the way down to the point of load. CUI's series of advanced intermediate bus converters are designed to optimize efficiency across a broader range of loading conditions. With the addition of the optional digital interface, an unparalleled level of flexibility to monitor and control the power system is provided. For more information, please visit our website.

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