AN911/1098 1/4 application note st6 micro is emc champion by david jacquinod & edouard presson since january 1996, electro-magnetic compliance is required by international law for any electrical equipment that is manufactured including a printed circuit board. as early as 1991, stmicroelectronics took this change in the law into account when planning the design and manufacture of the st62 microcontroller family. an emc environment was in- stalled in the design, quality and engineering center and st quality standards were enlarged to include emc performance criteria, with the result that the st62 microcontrollers meet the emc standards five years ahead of most 8-bit microcontrollers. figure 1. typical 8-bit microcontroller emission spectrum figure 2. st6225 emission spectrum 1
2/4 this dramatic lead makes the st62 microcontroller family ideally suited to creating emc com- pliant applications quickly and easily using standard pcbs and software. due to the fact that several emc norms apply to applications and not to components, stmi- croelectronics has created a methodology and specified component level criteria, that relate to application standards like iec 1000-4-4 or sae 1752/3. close customer collaboration has allowed the methodology to be fine-tuned and new emc tests have been created that are adapted to specific applications. figure 3. test bench for susceptibility measurement (fast transient voltage test) with the continuous progress of the diffusion process for integrated circuits, particularly with the shrinking chip geometries, the natural trend is to increasing clock speed and decreasing emc performance. to get a good compromise between clock speed and emc performance, the st62s, in the newer, faster technology versions, have a modified design that allows emc performance to be maintained or even improved. a set of emc design rules has been applied, and the electrical simulators like stspice, eldo, verilog allow the emc performance to be optimized.
3/4 ems trend with chip process scale factor. example (tested with fast transient voltage burst) : as an additional benefit, several architectural features of the st62 family permit applications to be optimized for emc quality: n possibility of hard wiring the watchdog enable n full accessibility of data/program spaces for selfcheck routines n triggers for all inputs. all the released st62 variants are available in otp/eprom versions which allow emc im- provements to be validated at pcb level and in functional tests with running software. an st62 application note has recently been published, describing how to develop with st62 from an emc perspective. figure 4. test bench for emission measurement scale factor (left) 1.2 m 0.8 m st6220 2kv 4kv
4/4 the present note which is for guidance only aims at providing customers with information regarding their products in order for them to save time. as a result, stmicroelectronics shall not be held liable for any direct, indirect or consequential damages with respect to any claims arising from the content of such a note and/or the use made by customers of the information contained herein in connexion with their products. information furnished is believed to be accurate and reliable. however, stmicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. n o license is granted by implication or otherwise under any patent or patent rights of stmicroelectronics. specifications mentioned in this publication are subject to change without notice. this publication supersedes and replaces all information previously supplied. stmicroelectronics products are not authorized for use as critical components in life support devices or systems without the express written approval of stmicroelectronics. the st logo is a registered trademark of stmicroelectronics ? 1998 stmicroelectronics - all rights reserved. purchase of i 2 c components by stmicroelectronics conveys a license under the philips i 2 c patent. rights to use these components in an i 2 c system is granted provided that the system conforms to the i 2 c standard specification as defined by philips. stmicroelectronics group of companies australia - brazil - canada - china - france - germany - italy - japan - korea - malaysia - malta - mexico - morocco - the netherlands - singapore - spain - sweden - switzerland - taiwan - thailand - united kingdom - u.s.a. http:/ /www.st.com
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