The vital role of the voltage reference in precision measurement systems

first_imgIn this 21st century environment, we change gadgets every year and expect them to work correctly, even if they don’t last all that long. They usually only survive until the next revision comes out, but that seems to be acceptable to most people. In contrast, there are many applications, such as field sensors, that demand high accuracy over a long period of time. A quick replacement for these devices would usually be unreasonable, and many times, impossible.Within the hostile environment of a field sensor, a key device in the electrical systems that monitor and measure oil, gas, pressure and/or temperature is the seemingly insignificant voltage reference. The role of the voltage reference in these systems is to be the analog gatekeeper by maintaining an absolute point of reference for all measurements and calculations. This can be quite a challenge given the extreme operating conditions experienced by these systems (Figure 1). Figure 1 High Mountain Weather Station Continue Reading Previous Top IoT concerns: security, connectivity, and dataNext Cadence: LPDDR4/4X memory IP subsystem achieves ISO 26262 ASIL C certification Share this:TwitterFacebookLinkedInMoreRedditTumblrPinterestWhatsAppSkypePocketTelegram Tags: Design Methods In this article, we will address not only the impact of two critical environmental variables, relative humidity (RH) and long-term drift (LTD) over time, but on the voltage reference gatekeeper and a winning solution that makes these variables a “nonissue”. The Voltage Reference Gatekeeper At its root, system accuracy depends on voltage reference devices. For instance, the system’s analog and digital converters use reference voltages to produce their digital results where the voltage reference value is an integral part of the output digital word (Figure 2). Figure 2 The SAR ADC Signal Path (A) and ΔΣ ADC Signal Path (B) Both Require Voltage References (REF) in the CircuitIn Figure 2, the left column shows a few of the more popular sensors. These signals can proceed through the (A) path, which finishes with the successive-approximation, analog-to-digital converter (SAR ADC) or the (B) path which finishes with a delta-sigma analog-to-digital converter (ΔΣ ADC). Both converters require a precision voltage reference (REF) to complete their conversion.In signal path (A) with the SAR ADC and in signal path (B) with the ΔΣ ADC, the converter’s LSB size is equal to:LSB = Vref /2N (Equation 1)where LSB = Least Significant BitV ref = Voltage reference voltageN = Number of ADC bitsFrom Equation 1, it is clear that the voltage reference has a direct influence on the accuracy of the converter’s system. Humidity and Drift vs. Time In field sensor applications, the electronics can experience large humidity excursions over time. As an example, the RH at the Mount Everest base camp can range from a maximum of 98% down to 20% throughout the year. This is equivalent to an RH delta of 78%. With systems in this environment, it is essential to guarantee equipment accuracy.The pathway to this guarantee is to utilize the most stable voltage reference. By reviewing the voltage reference alone, one can predict the stability of the system over time. Leave a Reply Cancel reply You must Register or Login to post a comment. This site uses Akismet to reduce spam. Learn how your comment data is processed.last_img read more

Draft policy to set up rooms for feeding infants in public places

first_imgNew Delhi: The AAP government has told the Delhi High Court that it has come up with a draft policy for setting up rooms for feeding and changing diapers of infants in public places and the process of placing the document in public domain for suggestions is underway. The court was informed that the Delhi government’s Department of Women and Child Development (WCD) has drafted the policy which has been circulated to all landowning departments and other public-dealing departments in July for inviting comments. Also Read – After eight years, businessman arrested for kidnap & murderThe court was hearing a public interest litigation (PIL) filed on behalf of a mother and her newborn seeking breastfeeding facilities in public places away from “censuring and dishonourable looks”. The Delhi government, in an affidavit filed in response to the petition, said, the Department of Urban Development (UD) has asked the WCD department to frame a state policy on ‘setting up of feeding room for the purpose of baby care room or nursing station or changing soggy diapers or feeding of infant in public places’. Also Read – Two brothers held for snatchings”Accordingly, on behalf of department of UD, the department of WCD has drafted a state policy by the name ‘setting up of feeding room for the purpose of baby care room or nursing station or changing soggy diapers or feeding of infant in public places’,” it said. The affidavit said that as soon as comments and suggestions are received from all stakeholders and public spirited persons, the same will be examined in consultation with the urban development department and other landowning agencies. “Suggestions/comments which are in public interest will be incorporated in the draft policy, thereafter, the same will be issued after seeking approval of government,” it said. The affidavit, filed before a bench of Chief Justice D N Patel and Justice C Hari Shankar, said the final policy will be sent to all stakeholders and landowning departments for its implementation and timelines will be sought so that the implementation can be monitored. The Delhi government said it is exploring the possibility of incorporating such rooms in future building plans and amendments to building bye-laws to implement the policy. Several consultations have been held with the civic bodies, the Delhi Development Authority (DDA) and the departments of women and child development, and urban development. The plea, filed through advocate Animesh Rastogi, contends that not providing such facilities amounts to “hampering” women’s right to privacy. The high court had earlier sought the stand of the Centre, the Delhi government and civic authorities here on the plea for providing facilities to mothers to breastfeed in public places, observing that such spaces were being provided all over the world.It had said the matter needs to be examined by all landowning agencies and civic bodies and issued notice to the municipal bodies and DDA, apart from the Centre and the Delhi government. It had noted there were no facilities to breastfeed even in airports here.last_img read more