SI7021-A10-IM1

Si 7 0 2 1 - A10 I 2 C H UMIDITY A N D TEMPERATURE S ENSOR Features       Precision Relative Humidity Sensor  ± 3% RH (max), 0–80% RH High Accuracy Temperature Sensor ±0.4 °C (max), –10 to 85 °C 0 to 100% RH operating range Up to –40 to +125 °C operating range Wide operating voltage (1.9 to 3.6 V) Low Power Consumption 150 µA active current 60 nA standby current  Factory-calibrated  I2C Interface Integrated on-chip heater 3x3 mm DFN Package Excellent long term stability Optional factory-installed cover Low-profile Protection during reflow Excludes liquids and particulates     Si7021 Ordering Information: See page 27. Applications HVAC/R Thermostats/humidistats  Respiratory therapy  White goods  Indoor weather stations Pin Assignments Micro-environments/data centers Automotive climate control and defogging  Asset and goods tracking  Mobile phones and tablets     Description The Si7021 I2C Humidity and Temperature Sensor is a monolithic CMOS IC integrating humidity and temperature sensor elements, an analog-to-digital converter, signal processing, calibration data, and an I2C Interface. The patented use of industry-standard, low-K polymeric dielectrics for sensing humidity enables the construction of low-power, monolithic CMOS Sensor ICs with low drift and hysteresis, and excellent long term stability. The humidity and temperature sensors are factory-calibrated and the calibration data is stored in the on-chip non-volatile memory. This ensures that the sensors are fully interchangeable, with no recalibration or software changes required. Top View SDA 1 6 SCL GND 2 5 VDD DNC 3 4 DNC Patent Protected. Patents pending The Si7021 is available in a 3x3 mm DFN package and is reflow solderable. It can be used as a hardware- and software-compatible drop-in upgrade for existing RH/ temperature sensors in 3x3 mm DFN-6 packages, featuring precision sensing over a wider range and lower power consumption. The optional factory-installed cover offers a low profile, convenient means of protecting the sensor during assembly (e.g., reflow soldering) and throughout the life of the product, excluding liquids (hydrophobic/oleophobic) and particulates. The Si7021 offers an accurate, low-power, factory-calibrated digital solution ideal for measuring humidity, dew-point, and temperature, in applications ranging from HVAC/R and asset tracking to industrial and consumer platforms. Rev. 1.1 6/15 Copyright © 2015 by Silicon Laboratories Si7021-A10 Si7021-A10 Functional Block Diagram Vdd Si7021 Humidity Sensor 1.25V Ref ADC Calibration Memory Control Logic Temp Sensor I2C Interface GND 2 Rev. 1.1 SDA SCL Si7021-A10 TABLE O F C ONTENTS Section Page 1. Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 2. Typical Application Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3. Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.1. Relative Humidity Sensor Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.2. Hysteresis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.3. Prolonged Exposure to High Humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 4.4. PCB Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.5. Protecting the Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.6. Bake/Hydrate Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.7. Long Term Drift/Aging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2 5. I C Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 5.1. Issuing a Measurement Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.2. Reading and Writing User Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 5.3. Electronic Serial Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23 5.4. Firmware Revision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 5.5. Heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 6. Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 6.1. Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 7. Pin Descriptions: Si7021 (Top View) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 8. Ordering Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 9. Package Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 9.1. Package Outline: 3x3 6-pin DFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 9.2. Package Outline: 3x3 6-pin DFN with Protective Cover . . . . . . . . . . . . . . . . . . . . . . 29 10. PCB Land Pattern and Solder Mask Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 11. Top Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31 11.1. Si7021 Top Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 11.2. Top Marking Explanation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 12. Additional Reference Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Document Change List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32 Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33 Rev. 1.1 3 Si7021-A10 1. Electrical Specifications Unless otherwise specified, all min/max specifications apply over the recommended operating conditions. Table 1. Recommended Operating Conditions Symbol Parameter Power Supply Test Condition Min Typ 1.9 VDD Max Unit 3.6 V Operating Temperature TA I and Y grade –40 — +125 °C Operating Temperature TA G grade –40 — +85 °C Table 2. General Specifications 1.9 < VDD < 3.6 V; TA = –40 to 85 °C (G grade) or –40 to 125 °C (I/Y grade); default conversion time unless otherwise noted. Parameter Symbol Test Condition Min Typ Max Unit Input Voltage High VIH SCL, SDA pins 0.7xVDD — — V Input Voltage Low VIL SCL, SDA pins — — 0.3xVDD V Input Voltage Range VIN SCL, SDA pins with respect to GND 0.0 — VDD V Input Leakage IIL SCL, SDA pins — — 1 μA VOL SDA pin; IOL = 2.5 mA; VDD = 3.3 V — — 0.6 V SDA pin; IOL = 1.2 mA; VDD = 1.9 V — — 0.4 V RH conversion in progress — 150 180 μA Temperature conversion in progress — 90 120 μA — 0.06 0.62 μA — 0.06 3.8 μA — 3.5 4.0 mA — 3.5 4.0 mA — 20 — μA — 3.1 — mA Output Voltage Low Current Consumption IDD Standby, –40 to +85 °C2 Standby, –40 to +125 °C 2 Peak IDD during powerup 3 Peak IDD during I2C operations4 After writing to user registers Heater Current6 IHEAT 5 Notes: 1. Initiating a RH measurement will also automatically initiate a temperature measurement. The total conversion time will be tCONV(RH) + tCONV(T). 2. No conversion or I2C transaction in progress. Typical values measured at 25 °C. 3. Occurs once during powerup. Duration is 200 kHz for 2-byte commands). 5. IDD after a user register write. Initiating any other subsequent I2C transaction on the same bus (such as the user register read, starting an RH measurement, or traffic directed at other I2C devices) will transition the device to standby mode. 6. Additional current consumption when HTRE bit enabled. See section “5.5. Heater” for more information 4 Rev. 1.1 Si7021-A10 Table 2. General Specifications (Continued) 1.9 < VDD < 3.6 V; TA = –40 to 85 °C (G grade) or –40 to 125 °C (I/Y grade); default conversion time unless otherwise noted. Parameter Conversion Time1 Powerup Time Symbol Test Condition Min Typ Max tCONV 12-bit RH — 10 12 11-bit RH — 5.8 7 10-bit RH — 3.7 4.5 8-bit RH — 2.6 3.1 14-bit temperature — 7 10.8 13-bit temperature — 4 6.2 12-bit temperature — 2.4 3.8 11-bit temperature — 1.5 2.4 From VDD ≥ 1.9 V to ready for a conversion, 25 °C — 18 25 From VDD ≥ 1.9 V to ready for a conversion, full temperature range — — 80 After issuing a software reset command — 5 15 tPU Unit ms ms Notes: 1. Initiating a RH measurement will also automatically initiate a temperature measurement. The total conversion time will be tCONV(RH) + tCONV(T). 2. No conversion or I2C transaction in progress. Typical values measured at 25 °C. 3. Occurs once during powerup. Duration is 200 kHz for 2-byte commands). 5. IDD after a user register write. Initiating any other subsequent I2C transaction on the same bus (such as the user register read, starting an RH measurement, or traffic directed at other I2C devices) will transition the device to standby mode. 6. Additional current consumption when HTRE bit enabled. See section “5.5. Heater” for more information Table 3. I2C Interface Specifications1 1.9  VDD  3.6 V; TA = –40 to +85 °C (G grade) or –40 to +125 °C (I/Y grade) unless otherwise noted. Parameter Symbol Test Condition Min Typ Max Unit Hysteresis VHYS High-to-low versus low-tohigh transition 0.05 x VDD — — V SCLK Frequency2 fSCL — — 400 kHz SCL High Time tSKH 0.6 — — µs SCL Low Time tSKL 1.3 — — µs Start Hold Time tSTH 0.6 — — µs Notes: 1. All values are referenced to VIL and/or VIH. 2. Depending on the conversion command, the Si7021 may hold the master during the conversion (clock stretch). At above 100 kHz SCL, the Si7021 may also hold the master briefly for user register and device ID transactions. At the highest I2C speed of 400 kHz the stretching will be