last update september 24, 2015 DATASHEET reference SMT172 V12 page 1/9 Features and Highlights Worlds most energy efficient temperature sensor Wide temperature range: -45 C to 130 C Extreme low noise: less than 0.001C High accuracy: 0.25C (-10 C to 100 C) 0.1 C (-20 C to 80 C, TO18) 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. last update september 24, 2015 DATASHEET reference SMT172 V12.0 page 2/9 Specifications TA= -45C to 130C, Vcc=2.7 V to 5.5 V, unless otherwise noted. PPPPaaaarrrraaaammmmeeeetttteeeerrrr MMMMiiiinnnn TTTTyyyypppp MMMMaaaaxxxx UUUUnnnniiiitttt CCCCoooonnnnddddiiiittttiiiioooonnnnssss 2.7 5.5 V Supply Voltage 1 50 A T = -45 C, Vcc = 2.7 V, no load at the output pin Active current A 60 A T = 25 C, Vcc = 3.3 V, no load at the output pin A 70 A T = 25 C, Vcc = 5.5 V, no load at the output pin A T = 25 C, Vcc = 3.3 V, one sample per second, each sample is based A 220 nA Average current on average of 16 output periods. Power down current 0 A When controlling with Vcc pin 2 Housing Accuracy TO18 0.25 C -10 C to 100 C TO18 0.8 C -45 C to 130 C TO18 0.1 C -20 C to 80 C (second order interpretation) TO18 0.4 C -45 C to 130 C (second order interpretation) TO92/TO220/SOT223 0.35 C -10 C to 100 C 1 C -45 C to 130 C TO92/TO220/SOT224 TO92/TO220/SOT223 0.25 C -20 C to 80 C (second order interpretation) TO92/TO220/SOT223 0.8 C -45 C to 130 C (second order interpretation) 5 First order relation betw een Duty Cyce and temperature : TTTT ==== 222211112222....77777777 DDDDCCCC ---- 66668888....000088885555 2222 Second order relation betw een Duty cycle and temperature : TTTT ==== ----1111....44443333 DDDDCCCC ++++222211114444....55556666 DDDDCCCC ---- 66668888....6666 3 <0.0002 C T = 25 C, Vcc = 5 V, 1 s measurement time Noise A Output Duty Cycle 0 1 DC = 0 at -68 C and 1 at 144.17 C Output frequency 0.5 7 kHz frequency range is 1 - 4 kHz for Vcc 4.7-5.5 V.(-25 C to 110 C) 0.1 C/V PSRR at Vcc 4 0.01 C T = 25C Repeatability A Startup time 1 2 ms after Vcc, start measurement on first negative edge Long term drift 0.05 C Output impedance 100 -45 130 C Operating Temperature Storage Temperature -50 150 C 1 Continuous conversion 2 all errors included. 3 Noise level will be reduced by averaging multiple consecutive samples, for instance noise can be reduced o 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.