High-accuracy Temps on PCBs

With SMD Pt RTDs

Surface Mount Device (SMD) {Shown much larger than actual size}, Image Courtesy Vishay Intertechnology, Inc.

Online –?? In a EDN, August 25th article entitled: “High-accuracy temperature measurements call for PRTDs and precision delta-sigma ADCs | Replaceable sensors and 24-bit ADCs ease measurement.” Sohail Mirza and Joseph Shtargot of Maxim Integrated Products talk about PRTDs in standard SMD (surface-mount-device) sizes.

That is: from 0.45 mm x 1.55 mm x 0.85 mm to 0.55 mm x 3.2 mm x 1.6 mm. Such products are available from several suppliers with prices in the few US dollar range. These devices substantially reduce sensor cost, empowering designers to place PRTDs on nearly any type of printed-circuit board (PCB).

They also state:

Modern PRTD standards, such as the IEC (International Electrotechnical Commission) 60751 and the ASTM (American Society of Testing and Materials) 1137, allow substantial interchangeability of sensors among systems based on their specified tolerance and temperature coefficients. These standards make it easy to replace a sensor with one from the same or a different manufacturer and ensure rated performance with minimal redesign or recalibration of the system.

They continue, working out specific design examples in great detail for two Vishay SMD Platinum sensors coupled with a Maxim delta-sigma ADC.

Visit: www.edn.com/article/519192-High_accuracy_temperature_measurements_call_for_PRTDs_and_precision_delta_sigma_ADCs.php to read the entire article and download the free References, called out in the article:

1. PTS Series – Pt-Sensors, Vishay Beyschlag, May 2011.
2. Lacanette, Kerry, Thermal Management Handbook, Application Note 4679, Maxim Integrated Products, May 4, 2010.
3. ???Design Considerations for a Low-Cost Sensor and A/D Interface???, Application Note 3775, Maxim Integrated Products, March 2006.