EZ-USB FX2 Assembly Recommenda- tions, Summary

AN1196

EZ-USB FX2 Assembly Recommenda- tions

The solder stencil over the exposed paddle is required to per- mit at least 50% solder application coverage. Figure 8 is a graph from Amkor research showing how solder void much less than 50% has little influence on thermal transfer. The package is a smaller one than the EZ-USB FX2 8-mm 56- lead package, but the values do scale.

Figure 8. Thermal Performance versus Solder Void

The manufacturing processes and practices of the assembly operation govern the stencil pattern used. Generally, arrays of either round or square patterns are used. A circular stencil was used for one assembly run of boards.

Figure 9. Stencil Area

Figure 9 shows that the stencil area contains 25 holes. The holes are 1 mm in diameter on a 1.25-mm pitch. The pad land on the PCB is 6 mm square. This results in a solder coverage of approximately 54 percent. A stencil could have fewer holes but they would need to be larger and may not meet the mini- mum 50% coverage requirement. A large pattern of four squares could also be used. However, the larger the opening of each hole or square the more likely solder sputtering or out-gassing problems will occur. A solder stencil thickness of 0.125 mm is recommended for this package. Figure 10 below displays a cross-sectional area underneath the package. The cross section is of only one via and is the recommended dimensions for the via.

Figure 10. Cross-section Area of via

Since there is no space under the package after soldering, it is recommended to use a “No Clean,” type 3 solder paste.

Nitrogen purge is recommended during solder reflow.

Summary

Following the recommendations of this application note should help the designer to produce a compliant and high- performance USB 2.0 device design. Compliance can be confirmed with testing at the often-scheduled USB-IF Compli- ance Workshops. To the extent possible, developers of USB products should test their designs for compliance prior to attending one of the Workshops.

November 21, 2002

Document No. 001-43117 Rev. **

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AN1196, EZ-USB FX2 PCB specifications

The Cypress EZ-USB FX2 is a high-speed USB microcontroller that serves as a versatile platform for connecting various devices to a USB interface. Designed for applications requiring a seamless and efficient USB communication system, the FX2 is widely used in data acquisition, imaging, and consumer electronics. The AN1196 application note is a pivotal resource that provides comprehensive guidance on utilizing the FX2 for developing USB peripherals.

One of the standout features of the Cypress EZ-USB FX2 is its ability to support high-speed USB 2.0 data transfer rates of up to 480 Mbps. This high bandwidth allows it to handle large data flows efficiently, making it suitable for applications such as high-resolution imaging or real-time data streaming. The FX2 architecture is designed to facilitate easy integration with various types of peripherals, allowing developers to create devices that communicate effectively over USB.

The FX2 microcontroller is built on an 8051 core, which is known for its low power consumption and efficient processing capabilities. With 64 Kbytes of on-chip RAM and 8 Kbytes of ROM, it provides ample resources for firmware and data storage. The built-in FIFO buffer is a significant advantage, enabling smooth data transfers between the USB interface and the device, thus reducing the complexity typically associated with USB communication.

A range of development tools and libraries simplifies the programming of the FX2 device. The EZ-USB developer toolkit includes libraries for quick integration and support for various development environments. This toolkit allows engineers to focus on higher-level application designs rather than getting bogged down in the intricacies of USB protocol implementation.

In terms of power management, the FX2 supports various modes to minimize power consumption during idle periods. This feature is particularly useful in battery-powered applications or scenarios where energy efficiency is crucial. Moreover, the device offers flexibility with its GPIO pins, allowing developers to configure them for different functionalities such as I2C, SPI, or GPIO operations, expanding its utility across various applications.

Overall, the Cypress EZ-USB FX2, together with the guidance provided in the AN1196 application note, equips developers with the resources needed to build robust USB solutions that cater to diverse market needs. Its combination of high-speed performance, low-power operation, and flexibility makes it a popular choice in the embedded systems community.