last update maart 18, 2015 DATASHEET reference V 2.0 SSSSMMMMTTTT111177772222 page 1/7 PPPPrrrreeeelllliiiimmmmiiiinnnnaaaarrrryyyy Features and Highlights Worlds most energy efficient temperature sensor Wide temperature range: -45 C to 130 C Extreme low noise: less than 0.001C Low inaccuracy: 0.25C (-10 C to 100 C) 1 Ultra low current (60 A active or 220 nA average) Wide supply voltage range: 2.7 V to 5.5 V Excellent long term stability Direct interface with Microcontroller (MCU) Wide range of package options Application Ultra low power applications: wearable electronics, wireless sensor networks Medical applications: body temperature monitoring Instrumentation: (Bio)chemical analysis, Precision equipment Environmental monitoring (indoor / outdoor) Industrial applications: process monitoring / controlling Introduction The SMT172 is an ultra-low power, high accuracy temperature sensor that combines the ease of use with the worlds leading performance over a wide temperature range. Using the most recent advances in the silicon temperature sensing technology, the SMT172 has applied some really sophisticated IC design techniques as well as high-precision calibration methods, to achieve an absolute inaccuracy of less than 0.25C in the range of -10 C to 100 C The SMT172 operates with a supply voltage from 2.7 V to 5.5 V. The typical active current of only 60 A, the high speed conversion over 4000 outputs per second (at room temperature) and an extremely low noise makes this sensor the most energy efficient temperature sensor in the world. The SMT172 has a pulse width modulated (PWM) output signal, where the duty cycle is proportional to the measured temperature value. This makes it possible that the sensor can interface directly to a MCU without using an Analog-to-Digital Converter (ADC). Today, the hardware Timer in a MCU to read our PWM signal has become available almost universally, fast in speed and low in cost. Therefore it is extremely easy for any user to get started with this sensor and achieve a very quick time to market. 1 See Specification Section for detailed measurement conditions last update maart 18, 2015 reference V2.0 SMT172 page Preliminary 2/7 Absolute Maximum Rating T = 25C. All voltages are referenced to GND, unless otherwise noted. A Power supply voltage -0.5 V to 7 V Output Pin load 50 mA ESD protection (HBM) +2000 V Junction temperature +200C Soldering temperature (SOIC, SOT) +260C (10 s) Specification TA= -45C to 130C, Vcc=2.7 V to 5.5 V, unless otherwise noted. PPaarraammeetteerr MMiinn TTyypp MMaaxx UUnniitt CCoonnddiittiioonnss PPaarraammeetteerr MMiinn TTyypp MMaaxx UUnniitt CCoonnddiittiioonnss Supply Voltage 2.7 5.5 V 1 Active current 50 A T = -45 C, Vcc = 2.7 V, no load at the output pin A 60 A TA = 25 C, Vcc = 3.3 V, no load at the output pin 70 A T = 25 C, Vcc = 5.5 V, no load at the output pin A Average current 220 nA TA = 25 C, Vcc = 3.3 V, one sample per second, each sample is based on average of 16 output periods. Power down current 1 A When controlling with dedicated PD pin, Vcc = 3.3 V(only SOIC) 0 A When controlling with Vcc pin 2 Inaccuracy 0.25 C -10 C to 100 C 0.8 C -45 C to 130 C 3 Noise <0.0001 C TA = 25 C, Vcc = 5 V, 1 s measurement time Output frequency 0.5 7 kHz PSRR at DC 0.1 C/V 4 Repeatability 0.01 C TA = 25C Long term drift 0.05 C Measured under 200 C stress test condition for 48 h Output impedance 100 Operating Temperature -45 130 C Storage Temperature -50 150 C 1 Continuous conversion 2 TO-18 package, all errors included. For other types of package, see section understanding the specifications-package induced error. For an inaccuracy of 0.1 C another conversion formula is needed please contact the factory. 3 o Noise level will be reduced by averaging multiple consecutive samples, for instance noise can be reduced to 0.0004 C by taking average in 0.1s, so the measurement time should always be provided when mentioning noise figures. The lower limit of the noise is determined by the flicker noise of the sensor, where further averaging will no longer reduce the noise. 4 Repeatability is defined as difference between multiple measurements on the same temperature point during multiple temperature cycles.