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An Analog Devices Inertial Sensor for Down-Hole Drilling

The temperature, shock and vibration requirements for components used in down-hole drilling are exceeded perhaps only by the requirements for components used in Hades, whatever those might be.  An oil well drill bit is not only subject to temperatures that may be beyond 200C, it is also subject to vibration while the bit is rotating and severe shock when the drill string is pulled or new sections are added.   Amazingly, Analog Devices new inertial sensor, part number ADXL206, which combines a MEMS accelerometer and the required logic on one IC, meets the down-hole requirements at a fraction of the cost and size of previous solutions. Oil wells are no longer only drilled straight down.  They are often drilled at a slant to reach an oil field from an accessible location.  They are also often threaded around obstacles such as water or hard rock.  This requires an extremely accurate measurement of the tilt and direction of the drill bit.  The Analog Devices inertial sensor provides that measurement.  This part also has an application when the well is completed, when it can be used to monitor vibration from the down-hole pump to provide an early warning of a potential failure of the pumping apparatus. The ADXL206 inertial sensor is a dual axis ±5g dual-axis accelerometer, which can operate from -40C to +175C.  It has diminishing performance above 175C, but is 100% recoverable.  Oil well drillers will calibrate the output of the part and use it at temperatures above 175C, a usual practice in the industry.  It has a long life, a guaranteed minimum 1000 hours at 175C.  It has high sensitivity and accuracy. The ADXL206 is packaged in a 13mm X 8mm X 2 mm ceramic, dual in-line package, a tiny but rugged package, which replaces packages that can be up to the size of a hockey puck.  This part will sell at well under $1,000 in 1,000 piece quantities.  It will replace inertial sensors that sell for thousands of dollars. Although the ADXL206 was designed for down-hole applications, Semico believes it is sure to find a home in other applications that require operation in severe environments.  Although none of these have materialized yet, that there may be applications in steel mills, blast furnaces, high temperature test ovens or other high temperature locations.  The ADXL206 has a unique set of characteristics.  There are, no doubt, design engineers who have set of requirements that have defied solution for years, requirements that match the specifications of Analog Devices part ADXL206.  They will be overjoyed to see this part. Tony Massimini Chief Technical Officer

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