PIERCE ANALYZER SYSTEM (PAS) ADVANCED BOARD CHARACTERIZATION SERVICE PAS-BC3WK INTRODUCTION: The majority of electronic designs have some form of timing associated with them. Depending on the frequency accuracy requirements, some employ oscillators while others use off-the-shelf crystals in conjunction with the built-in oscillator circuit; embedded in most controllers and processors. Most if not all embedded solutions use the Pierce Oscillator configuration, integrated as part of the SOC (system on chip). The obvious advantages include cost, size and power compared to a stand-alone oscillator; while the key limitation is the proper matching of the quartz crystal with the on-board Pierce Oscillator. Figure (1) outlines the oscillator block and the key components that influence the overall performance of the timing loop. Effective Loaded Capacitance, as seen by the Crystal = CL CL = {((Cin+C1) x (C2+Cout)) / (Cin+C1+C2+Cout)} + Board Strays For example; Let C1 = C2 = 27 pF; Cin = 5.0 pF & Cout = 10.0 pF and Board Strays = 0.50 pF then; CL = { ((27+5) x (27+10)) / (5+27+27+10) } + 0.50 = 17.65 pF Therefore specifying a crystal with 18.0 pF plating load capacitance would be the closest match for frequency accuracy. Besides the frequency accuracy issue, while accounting for Quartz Crystal's set tolerance; the reactive impedance (Xc) of the loop capacitors, in combination with the Inverter Amplifier's transconductance (gm), the current limiting resistor Rs and the presence or absence of the AGC or ALC circuit as part of the oscillator loop - determines the boundary condition of the design. This boundary condition, commonly referred to as the Safety Factor (SF), is an important parameter to ensure that the product design has sufficient margin to accommodate part-to-part and lot-to-lot variations; as well as eliminating product performance uncertainty in production volume. ABRACON IS ISO9001:2008 CE CERTIFIED RTIFIED Visit www.abracon.com for Terms & Conditions of Sale Revised: 03.12.12 30332 Esperanza, Rancho Santa Margarita, California 92688 tel 949-546-8000 | fax 949-546-8001 | www.abracon.com PIERCE ANALYZER SYSTEM (PAS) ADVANCED BOARD CHARACTERIZATION SERVICE PAS-BC3WK | | Historically, design engineers have optimized their circuit performance via trial & error, at the expense of significant investment in time. Further, to properly determine the oscillator loop dynamics, there is no other choice but to break the oscillator loop and make key measurements using specialized equipment such as a Current Probe. Lastly, these measurements become increasingly sensitive if the timing loop is driven by a Tuning Fork (32.768kHz) crystal. These crystals are extremely sensitive to loading effects and to accurately determine the in-circuit behavior of these components, extreme care and accuracy is essential. For instance, Automotive, Medical and Consumer Electronics solutions typically utilize Tuning Fork Crystals for their Real-Time-Clocking (RTC) needs. If the selected SOC has inadequate gain margin, there is a high probability that some percentage of these Crystals will not properly start under adverse conditions, such as low operating temperature. Another example would be a Zigbee based design which has a hard boundary condition of 40 ppm relative to the carrier, for proper operation. If the oscillator loop is not optimized, most of the 40 ppm can be consumed by tolerance alone; thereby causing significant fall out in the field. In summary, a typical product launch requires significant investment of capital and design resources. Making a very modest investment in characterizing the timing loop is a must have to protect this investment, as well as mitigate risk of field failures or warranty re-calls. SOLUTION: To overcome these barriers and provide an accurate assessment of the oscillator loop dynamics; Abracon's Advanced Engineering Team has developed a Proprietary Pierce Analyzer System (PAS); which is designed to analyze both the stand alone crystal, as well as the performance of that particular crystal in customer's circuit. ABRACON IS ISO9001:2008 CE CERTIFIED RTIFIED Visit www.abracon.com for Terms & Conditions of Sale Revised: 03.12.12 30332 Esperanza, Rancho Santa Margarita, California 92688 tel 949-546-8000 | fax 949-546-8001 | www.abracon.com PIERCE ANALYZER SYSTEM (PAS) ADVANCED BOARD CHARACTERIZATION SERVICE PAS-BC3WK FEATURES: * Circuit characterization; providing best possible match between Quartz Crystal, oscillator loop and associated components * Eliminates probability of oscillator start-up issues related to inadequate design or marginal component performance * Eliminates production launch issues related to crystal oscillator based timing circuit * Solves for design margin uncertainty * Provides customer's oscillator circuit overview in the form of a detailed report, which could be an ideal 3rd party assessment for the design history file or PPAP documentation. This report encompasses both the stand-alone crystal performance, as well as in-circuit behavior outlining safety factor as a function of crystal's ESR, etc. * For additional information, please contact Abracon at: tech-support@abracon.com DELIVERABLES: Abracon provides a detailed test report encompassing: * Stand alone Quartz Crystal characteristics including: - Motional parameters (Cm, Lm, ESR &Co) - Narrow Band Frequency Response Plot - Wide Band Frequency Response PlotoAdmittance versus Suseptance Plot - Frequency dependence versus load capacitance plot * Oscillator loop - Initial frequency accuracy and drive level as seen by the crystal with measured ESR - Worst case projected drive level with maximum specified ESR - Safety Factor of the oscillator loop under both typical and maximum ESR - Recommendation on proper component selection (C1, C2 & Rs when applicable) for best compromise with respect to Safety Factor and Frequency accuracy - Recommendation on the Abracon Crystal part # with proper plating load and other key attributes to enable the most robust design, specific to the controller/processor implemented ORDERING INFO: PAS-BC1WK PAS-BC2WK PAS-BC3WK Analysis & Report with 1-week maximum lead-time Analysis & Report with 2-week maximum lead-time Analysis & Report with 3-week maximum lead-time ATTENTION: Abracon Corporation's products are COTS - Commercial-Off-The-Shelf products; suitable for Commercial, Industrial and, where designated, Automotive Applications. Abracon's products are not specifically designed for Military, Aviation, Aerospace, Life-dependant Medical applications or any application requiring high reliability where component failure could result in loss of life and/or property. For applications requiring high reliability and/or presenting an extreme operating environment, written consent and authorization from Abracon Corporation is required. Please contact Abracon Corporation for more information. IS ABRACON IS ISO9001:2008 CERTIFIED CERTIFIED Visit www.abracon.com for Terms & Conditions of Sale Revised: 03.12.12 30332 Esperanza, Rancho Santa Margarita, California 92688 tel 949-546-8000 | fax 949-546-8001 | www.abracon.com Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: ABRACON: PAS-BC1WK PAS-BC2WK PAS-BC3WK