Proving the Business Case for the Internet of Things

Temperature sensors maintain accuracy for asset tracking and other IoT applications

Steve Rogerson
January 14, 2015
High-precision temperature sensors have been introduced by Silicon Labs for HVAC, white goods, computer equipment, asset tracking, cold chain storage, industrial control and medical equipment. AEC-Q100-qualified versions are also available for automotive applications.
The Si705x temperature sensors consume 195nA typical average current when sampled once per second, which reduces self-heating and enables multi-year coin cell battery operation. Unlike traditional digital temperature sensors, the devices maintain their accuracy across the full operating temperature and voltage ranges and provide four accuracy levels up to ±0.3ËšC.
Traditional approaches to temperature sensing that use thermistors or embedded MCU temperature sensors suffer from poor accuracy and higher power consumption. Although improved accuracy can be achieved through end-of-line calibration, this technique can lead to additional manufacturing costs and difficulties while accuracy is still susceptible to variations in power supply voltage.
In contrast, the Si705x sensors’ signal processing technology provides stable temperature accuracy over the entire operating voltage and temperature ranges without the need for costly end-of-line production calibration. In addition, the integrated low-power analogue design delivers an optimal price-performance ratio with a claimed up to 35 times better power efficiency than competing temperature sensor products.
“Temperature is the most pervasive environmental metric that embedded developers need to measure, and today’s designers expect exceptional power efficiency, accuracy and price-performance from their temperature sensing solutions,” said Ross Sabolcik, vice president and general manager of Silicon Labs. “Although many competing options are available for temperature sensing, the Si705x devices provide the most power-efficient option while maintaining accuracy across the entire operating voltage and temperature range so developers don’t need to compromise on performance.”
Available in a 3 by 3 mm DFN package, the sensors have an industry-standard I2C interface for easy configuration. Each device provides up to 14bit temperature resolution for high-precision measurement, and the -40 to +125ËšC temperature range is suitable for consumer, industrial and automotive applications. With a 1.9 V minimum power supply voltage, the sensors can be connected directly to a battery without the need for an external voltage regulator.
The temperature sensors are the latest members of Silicon Labs’ growing portfolio of environmental and optical sensor products for the IoT, consumer and industrial automation markets. The range includes relative humidity and temperature sensors, proximity and ambient light sensors, UV index and ambient light sensors, and capacitive touch sensors, as well as isolated AC sensors and high-side DC sensors for power management applications.
The Si705x sensors are pin-compatible and software-compatible with the company’s Si70xx relative humidity and temperature sensor family. This compatibility enables existing relative humidity sensor designs and software to be reused for temperature-only applications.