FeaturePak Backgrounder

This FeaturePak Backgrounder introduces the FeaturePak concept and briefly describes its features and benefits.

Why FeaturePak?

The FeaturePak I/O module standard is intended to provide a compact and low-cost method of adding I/O to board-level embedded computers. FeaturePaks can be used as snap-in customization modules for commercial, off-the-shelf single-board computers (SBCs) and computer-on-module (COM) baseboards, or as functional blocks on fully-custom embedded electronics.

Key features and benefits of FeaturePak are summarized in the table below:

FeaturePak Features
FeaturePak Benefits
  • Compact, low profile form-factor — 3/5 the size of a credit card and 1/3 the size of a PC/104 module

  • Single low-cost connector integrates all host and external I/O interfaces
  • Provides up to 100 I/O points per module
  • Leverages industry-standard buses such as PCIe, USB, and I2C
  • Host processor and form-factor agnostic
  • Coexists with PC/104, SUMIT, Qseven, ETX, XTX, COM Express, etc.
  • Multiple FeaturePaks may be present within one system
  • Zero height expansion module
  • Open industry standard
  • Rugged and reliable
  • Shortens time-to-market

  • Reduces board-level development costs and risks
  • Simplifies system design
  • Eliminates cables, resulting in higher reliability, lower cost, and faster assembly
  • Enables scalable and reconfigurable system design
  • Enables easy product upgrades
  • Protects from component obsolescence
  • Encapsulates intellectual property
  • Suitable for SBCs, baseboards, and proprietary all-in-one hardware designs
  • Ideal for rapid-prototyping through high-volume applications
  • Ideal format for silicon vendor reference designs
  • Open standard increases market acceptance

FeaturePak Host and External I/O Connections

The figure below illustrates the FeaturePak connector’s host and external I/O bus signals:

(Click image to enlarge)

As seen in the illustration, all connections — including power, host interface, and I/O — appear on a single low-cost, high-density “MXM” connector, originally designed for use with notebook computer graphics modules. The FeaturePak module inserts into the connector at an angle and then swings down to lie parallel to the host PCB. The module is then secured with two screws.

The use of a single low-cost connector plus gold fingers on the FeaturePak module results in the lowest possible cost for a mezzanine board interconnect solution. The MXM connector is rated for 2.5Gbps operation, fast enough for PCI Express and other high speed serial interfaces, including USB 2.0 and gigabit Ethernet.

It should be noted that the FeaturePak standard’s utilization of the 230-pin MXM connector differs from that of the MXM graphics standard, as well as from other standards that employ MXM connectors, such as Qseven COMs.

FeaturePak signal groups

The FeaturePak module’s 230-position gold finger interface is partitioned into three groups:

  • Host interface — includes 2 PCI Express x1 links, 2 USB (1.1 or 2.0) channels, 1 serial port (TX, RX, RTS, CTS), SMBus, reset, JTAG, auxiliary signals, a slot ID, +3.3V, +12V, and ground.
  • Primary I/O signal group — includes 50 I/O signals, +5V, and ground. Within this group, 34 signal pairs are implemented with enhanced isolation for use in applications such as high precision analog, Ethernet, and optoisolated I/O.
  • Secondary I/O signal group — includes 50 general purpose I/O signals, +5V, and ground.

These signals are illustrated in the figure below.

FeaturePak Architecture
(Click image to enlarge)

Power considerations

FeaturePak modules operate on 3.3V, although they may optionally use 5V power for auxiliary functions (depending on the specific FeaturePak module). All logic levels are implemented with standard 3.3V signaling.

Based on the MXM connector’s maximum per-pin current rating of 0.5A and the number of defined power pins on the FeaturePak interface, maximum FeaturePak module power consumption is 12W from its 3.3V inputs. Additionally, up to 15W of power can be supplied to a FeaturePak via its optional 5V DC inputs. The connector’s +12V interface pin is not intended for powering the module.

FeaturePak “compliance” and “compatibility”

The FeaturePak standard defines two types of expansion slots: FeaturePak and FeaturePak USB. Each type defines a minimum feature set for interchangeability with the open market of FeaturePak modules. The only difference between the two is the number of PCIe and USB links. A host board must provide the following minimum features to the MXM connector to be called “FeaturePak™ compliant” or “FeaturePak™ USB compliant.”

For host boards to be fully FeaturePak compliant they need to provide at least the following functions: +3.3V at 2A, +5V at 1A, 1 x1 PCI Express lane, PCI Express reset, 1 USB port (1.1 or 2.0), and Slot ID. FeaturePak USB compliant host boards, on the other hand, must provide at least these functions: +3.3V at 2A, +5V at 1A, PCI Express reset, 2 USB ports (1.1 or 2.0), and Slot ID.

FeaturePak modules, on the other hand, are permitted to implement subsets of the host interface signals (although a future release of the FeaturePak Specification will likely define certain minimum requirements). Thus, a FeaturePak might communicate with the host board using any combination of PCI Express, USB, and serial interfaces. All subsets of these interfaces are permitted, resulting, for example, in possibilities such as a USB-interfaced serial expansion module, a serial-interfaced GPS module, or a PCIe-interfaced video framegrabber.

Ways to use FeaturePaks

With their compact size and standardized connector, FeaturePaks are easy-to-use macrocomponents that target a wide range of embedded applications. Embedded computer design can be greatly simplified by treating complex I/O subsystems as components, just as various types of COMs (computer-on-modules) allow designers to treat the core embedded computing functions as a plug-in building block. This macrocomponent approach greatly accelerates design cycles, and also enables the creation of reconfigurable and upgradable products.

Seen from that perspective, there is nearly an endless array of FeaturePak use cases. The figures below illustrate a few anticipated FeaturePak instances.

FeaturePak on SUMIT-ISM and PCIe/104 modules
(Click each image to enlarge)


FeaturePak on a COM Express baseboard
(Click image to enlarge)


FeaturePak on a Qseven baseboard
(Click image to enlarge)


FeaturePak on an EPIC Express SBC
(Click image to enlarge)


Further Information

To contact the FeaturePak Trade Association, please send an email to featurepak@gmail.com or use our contact form. Further information is available from the following FeaturePak pages or publications:


Join the FeaturePak Trade Association

Learn how your company can become a member of the FeaturePak Trade Association, here.

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