Si7005 D IGITA L I 2 C H UMIDITY AND TEMPERATURE S ENSOR Features Relative Humidity Sensor ± 4.5% RH (maximum @ 0–80% RH) Temperature Sensor ±0.5 ºC accuracy (typical) ±1 ºC accuracy (maximum @ 0 to 70 °C) 0 to 100% RH operating range –40 to +85 °C (GM) or 0 to +70 °C operating range (FM) Wide operating voltage range (2.1 to 3.6 V) Low Power Consumption 240 µA during RH conversion I2C host interface Integrated on-chip heater 4x4 mm QFN package Excellent long term stability Factory calibrated Optional factory-installed cover Low-profile Protection during reflow liquids and particulates (hydrophobic/oleophobic) Ordering Information Excludes See Ordering Guide. Patent protected; patents pending Applications DNC DNC DNC DNC DNC GND 22 21 20 19 1 18 DNC DNC 2 17 DNC SCL 3 16 DNC 11 12 DNC 13 DNC GND DNC 10 14 DNC 6 CEXT 15 CS 5 9 4 VDD SDA DNC 8 The Si7005 is a digital relative humidity and temperature sensor. This monolithic CMOS IC integrates temperature and humidity sensor elements, an analog-to-digital converter, signal processing, calibration data, and an I2C host interface. The patented use of industry-standard, low-K polymeric dielectrics for sensing humidity enables the construction of a low-power, monolithic CMOS sensor IC with low drift and hysteresis and excellent long term stability. GND 7 Description 23 Micro-environments/data centers Automotive climate control and de-fogging Asset and goods tracking 24 Pin Assignments DNC Industrial HVAC/R Thermostats/humidistats Respiratory therapy White goods GND Both the temperature and humidity 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. The Si7005 is packaged in a 4x4 mm QFN package and is reflow solderable. The optional factory-installed protective cover offers a lowprofile, 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 Si7005 offers an accurate, low-power, factory-calibrated digital solution ideal for measuring temperature, humidity, and dew-point in applications ranging from HVAC/R and asset tracking to industrial and consumer platforms. Rev. 1.4 1/16 Copyright © 2016 by Silicon Laboratories Si7005 Si7005 Functional Block Diagram CEXT MUX ADC Temperature Sensor GND 2 Si7005 Rev. 1.4 Logic I2C Serial IF I2C pullups may be integrated in microcontroller 32 kHz Osc Humidity Sensor R = 10 k (typ) NV CAL VDD C = 4.7 µF C = 0.1 µF VDD R = 10 k (typ) VDD SCL PXx SDA PXy PXz CS Microcontroller Si7005 TABLE O F C ONTENTS Section Page 1. Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 2. Typical Application Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3. Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4.2. Relative Humidity Sensor Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.3. Linearization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.4. Temperature Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 4.5. Hysteresis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 4.6. Prolonged Exposure to High Humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 4.7. PCB Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.8. Protecting the Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 4.9. Bake/Hydrate Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 4.10. Long Term Drift/Aging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 5. Host Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.1. I2C Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 5.2. I2C Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23 6. Si7005 Connection Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 7. Control Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27 7.1. Register Detail (Defaults in Bold) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 8. Pin Descriptions: Si7005 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30 9. Ordering Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 10. Package Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32 10.1. 24-Pin QFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 10.2. 24-Pin QFN with Protective Cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 11. PCB Land Pattern and Solder Mask Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 12. Top Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36 12.1. Si7005 Top Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 12.2. Top Marking Explanation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 13. Additional Reference Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Document Change List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38 Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39 Rev. 1.4 3 Si7005 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 VDD Min Typ Max Unit 2.1 3.3 3.6 V Operating Temperature TA G grade –40 — 85 °C Operating Temperature TA F grade 0 — 70 °C Table 2. General Specifications 2.1 VDD 3.6 V; TA = 0 to 70 °C (F grade) or –40 to 85 °C (G grade) unless otherwise noted. Parameter Symbol Test Condition Min Typ Max Unit Input Voltage High VIH CS, SCL, SDA pins 0.7xVDD — — V Input Voltage Low VIL CS, SCL, SDA pins — — 0.3xVDD V Input Voltage Range VIN SCL, SDA pins with respect to GND 0.0 — 3.6 V CS, CEXT pin with respect to GND 0.0 — VDD V IIL CS, SCL, SDA pins — — ±1 µA VOL SDA pin; IOL = 8.5 mA; VDD = 3.3 V — — 0.6 V SDA pin; IOL = 3.5 mA; VDD = 2.1 V — — 0.4 V Input Leakage Output Voltage Low Notes: 1. Si7005 can draw excess current if VDD and CS are ramped high together. To enter the lowest power mode, either hold CS low while VDD ramps or pulse CS low after VDD reaches its final value. 2. SDA and SCL pins have an internal 75 k pull-up resistor to VDD. 4 Rev. 1.4 Si7005 Table 2. General Specifications (Continued) 2.1 VDD 3.6 V; TA = 0 to 70 °C (F grade) or –40 to 85 °C (G grade) unless otherwise noted. Parameter Power Consumption Conversion Time Symbol Test Condition Min Typ Max Unit IDD RH conversion in progress — 240 560 µA Temperature conversion in progress — 320 565 µA Average for 1 temperature and 1 RH conversion / minute — 1 — µA CS < VIL; no conversion in progress; VDD = 3.3 V; SDA = SCL ≥ VIH — 150 — µA CS > VIH — — 100 µA CS < VIL; no conversion in progress; VDD = 3.3 V; SDA = SCL ≥ VIH; HEAT = 1 — 24 31 tCONV mA 14-bit temperature; 12-bit RH (Fast = 0) 35 40 13-bit temperature; 11-bit RH (Fast = 1) 18 21 ms Wake Up Time tCS From CS < VIL to ready for a temp/RH conversion 10 15 ms Power Up Time tPU From VDD ≥ 2.1V to ready for a temp/RH conversion 10 15 ms Notes: 1. Si7005 can draw excess current if VDD and CS are ramped high together. To enter the lowest power mode, either hold CS low while VDD ramps or pulse CS low after VDD reaches its final value. 2. SDA and SCL pins have an internal 75 k pull-up resistor to VDD. Rev. 1.4 5 Si7005 Table 3. I2C Interface Specifications* 2.1 VDD 3.6 V; TA = 0 to 70 °C (F grade) or –40 to +85 °C (G 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 Frequency fSCL — — 400 kHz SCL high time tSKH 0.6 — — µs SCL low time tSKL 1.3 — — µs Start hold time tSTH 0.6 — — µs Start setup time tSTS 0.6 — — µs Stop setup time tSPS 0.6 — — µs Bus free time tBUF 1.3 — — µs SDA setup time tDS 100 — — ns SDA hold time tDH 100 — — ns SDA valid time tVD;DAT From SCL low to data valid — — 0.9 µs SDA acknowledge valid time tVD;ACK From SCL low to data valid — — 0.9 µs Between Stop and Start *Note: All values are referenced to VIL and/or VIH. tSKH 1/fSCL tSKL SCL tBUF tSTH tDS D7 SDA D6 tDH D5 D0 tSPS R/W ACK Start Bit Stop Bit tVD : ACK tSTS Figure 1. I2C Interface Timing Diagram 6 Rev. 1.4 Si7005 Table 4. Humidity Sensor 2.1 VDD 3.6 V; TA = 25 °C; tCONV = 35 ms unless otherwise noted. Parameter Symbol Operating Range1 Test Condition Min Typ Max Unit Non-condensing 0 — 100 %RH — — 12 bit — ±3.0 ±4.5 %RH Resolution2 Accuracy3,4 20–80% RH 0–100% RH See Figure 2 Repeatability—Noise — 0.05 — %RH RMS — 18 — s Hysteresis — ±1 — %RH Long Term Stability4 — 0.25 — %RH/yr 63% Response Time5 1 m/s airflow Notes: 1. Recommended humidity operating range is 20 to 80% RH (non-condensing) over 0 to 60 °C. Prolonged operation beyond these ranges may result in a shift of sensor reading, with slow recovery time. 2. The Si7005 has a nominal output of 16 codes per %RH, with 0h0000 = –24%RH. 3. Excludes hysteresis, long term drift, and certain other factors and is applicable to non-condensing environments only. See section “4.2. Relative Humidity Sensor Accuracy” for more details. 4. May be impacted by dust, vaporized solvents or other contaminants, e.g., out-gassing tapes, adhesives, packaging materials, etc. See section “4.10. Long Term Drift/Aging”. 5. Time for sensor output to reach 63% of its final value after a step change. RHAccuracy Max.RHError(±%) Typ.RHError(±%) 10 RHMeasurementError(±%) 9 8 7 6 5 4 3 2 1 0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 RelativeHumidity(%) Figure 2. RH Accuracy at 30 °C Rev. 1.4 7 Si7005 Table 5. Temperature Sensor 2.1 VDD 3.6 V; TA = 0 to 70 °C (F grade) or –40 to +85 °C (G grade); tCONV = 35 ms unless otherwise noted. Parameter Symbol Test Condition Min Typ Max Unit –40 — 85 °C — — 14 Bit — — 1/32 °C — ±0.5 ±1.0 °C Operating Range Resolution1 Accuracy2 Typical at 25 °C Maximum See Figure 3. Repeatability—Noise Response Time3 Time to reach 63% of final value Long Term Stability °C — 0.1 — °C RMS — 1.5 — s — <0.05 — °C/yr Notes: 1. The Si7005 has a nominal output of 32 codes /°C, with 0000 = –50 °C 2. Temperature sensor accuracy is for VDD = 2.3 to 3.6 V. 3. Actual response times will vary dependent on system thermal mass and air-flow. TemperatureAccuracy Max.TError(°C) Typ.TError(°C) 3.5 3 2.5 2 1.5 1 Temperature(°C) Figure 3. Temperature Accuracy 8 Rev. 1.4 125 120 115 110 105 95 100 90 85 80 75 70 65 60 55 50 40 45 35 30 25 20 15 5 10 0 Ͳ5 Ͳ10 Ͳ20 Ͳ15 Ͳ25 Ͳ30 0 Ͳ35 0.5 Ͳ40 TemperatureMeasurementError(°C) 4 Si7005 Table 6. Thermal Characteristics Symbol Test Condition QFN-24 Unit Junction-to-Air Thermal Resistance JA JEDEC 4-layer board 55 °C/W Junction-to-Air Thermal Resistance JA 2-layer evaluation PCB with minimal thermal pad 110 °C/W Parameter Table 7. Absolute Maximum Ratings1,2 Min Typ Max Unit Ambient Temperature under Bias –55 — 125 °C Storage Temperature –65 — 150 °C Voltage on SDA or SCL pin with respect to GND –0.3 — 3.9 V Voltage on CS pin with respect to GND –0.3 — VDD + 0.3 V Voltage on VDD with respect to GND –0.3 — 4.2 V HBM — — 3 kV CDM — — 750 V MM — — 300 V Parameter ESD Tolerance Symbol Test Condition Notes: 1. Absolute maximum ratings are stress ratings only; operation at or beyond these conditions is not implied and may shorten the life of the device or alter its performance. 2. For best accuracy, after removal from the sealed shipping bags, the Si7005 should be stored in climate controlled conditions (10 to 35 °C, 20 to 60 %RH). Exposure to high temperature and/or high humidity environments can cause a small upwards shift in RH readings. Rev. 1.4 9 Si7005 2. Typical Application Circuits 20 GND 19 21 DNC DNC DNC 16 14 13 DNC VDD 15 12 8 GND DNC 7 17 CS DNC DNC 6 18 DNC Si7005 SDA 5 DNC 22 23 DNC U1 SCL 4 SDA DNC 9 SCL DNC DNC 11 3 GND Cext 2 GND R2 10K 10 1 R1 10K DNC EPAD VDD DNC 25 24 Note: If the Si7005 shares an I2C bus with other slave devices, it should be powered down when the master controller is communicating with the other slave devices. The Si7005 can be powered down either by setting the CS signal to logic high or setting the VDD pin to 0 V. Refer to Figure 5 for an illustration of this method of powering the Si7005 from an MCU GPIO (the Si7005 VDD is powered from an MCU port pin). CSb C1 4.7uF C2 0.1uF GND SDA 20 GND 19 DNC DNC 21 DNC 22 DNC DNC 18 17 16 15 14 13 12 DNC DNC 7 C1 4.7uF CS DNC DNC 6 DNC Si7005 GND 5 U2 SCL 11 SDA DNC Cext 4 DNC 10 SCL DNC VDD 3 GND 9 2 GND R2 10K 8 1 R1 10K DNC EPAD 15.0 23 R3 Port Pin DNC 25 VDD 24 Figure 4. Typical Application Circuit C2 0.1uF GND Figure 5. Typical Application Circuit for Battery-Powered Applications 10 Rev. 1.4 Si7005 3. Bill of Materials Table 8. Typical Application Circuit BOM Reference Description Mfr Part Number Manufacturer C1 Capacitor, 4.7 µF, 6.3 V, X5R, 0603 C0603X5R6R3-475M Venkel C2 Capacitor, 0.1 µF, 6.3 V, X7R, 0603 C0603X7R6R3-104M Venkel R1* Resistor, 10 k, ±5%, 1/16W, 0603 CR0603-16W-1002J Venkel R2* Resistor, 10 k, ±5%, 1/16W, 0603 CR0603-16W-1002J Venkel U1 IC, digital temperature/humidity sensor Si7005 Silicon Labs *Note: Typical value shown. Optimal value depends on bus capacitance and speed of bus operation; not needed if present elsewhere in the system. Table 9. Typical Application Circuit for Battery-Powered Applications BOM Reference Description Mfr Part Number Manufacturer C1 Capacitor, 4.7 µF, 6.3 V, X5R, 0805 C0805X5R160-475M Venkel C2 Capacitor, 0.1 µF, 6.3 V, X7R, 0603 C0603X7R6R3-104M Venkel R1* Resistor, 10 k, ±5%, 1/16W, 0603 CR0603-16W-1002J Venkel R2* Resistor, 10 k, ±5%, 1/16W, 0603 CR0603-16W-1002J Venkel R3 Resistor, 15 , ±5%, 1/16W, 0603 CR0603-16W-15R0J Venkel U1 IC, digital temperature/humidity sensor Si7005 Silicon Labs *Note: Typical value shown. Optimal value depends on bus capacitance and speed of bus operation; not needed if present elsewhere in the system. Rev. 1.4 11 Si7005 4. Functional Description CEXT MUX ADC Temperature Sensor GND Logic I 2C Serial IF Si7005 I2C pullups may be integrated in microcontroller 32 kHz Osc Humidity Sensor R = 10 k (typ) NV CAL VDD C = 4.7 µF C = 0.1 µF VDD R = 10 k (typ) V DD SCL PXx SDA PXy PXz CS Microcontroller Figure 6. Si7005 Functional Block Diagram 4.1. Overview The Si7005 is a digital relative humidity and temperature sensor. This monolithic CMOS IC integrates temperature and humidity sensor elements, an analog-to-digital converter, signal processing, calibration data, and an I2C host interface. Both the temperature and humidity sensors on each unit 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. While the Si7005 is largely a conventional mixed-signal CMOS integrated circuit, relative humidity sensors in general and those based on capacitive sensing using polymeric dielectric have unique application and use requirements that are not common to conventional (non-sensor) ICs. Chief among those are: The need to protect the sensor during board assembly, i.e., solder reflow, and the need to subsequently rehydrate the sensor. The need to protect the sensor from damage or contamination during the product life-cycle The impact of prolonged exposure to extremes of temperature and/or humidity and their potential affect on sensor accuracy The effects of humidity sensor “memory” The need to apply temperature correction and linearization to the humidity readings Each of these items is discussed in more detail in the following sections. 12 Rev. 1.4 Si7005 4.2. Relative Humidity Sensor Accuracy To determine the accuracy of a relative humidity sensor, it is placed in a temperature and humidity controlled chamber. The temperature is set to a convenient fixed value (typically 30 °C) and the relative humidity is swept from 20 to 80% and back to 20% in the following steps: 20% – 40% – 60% – 80% – 80% – 60% – 40% – 20%. At each set-point, the chamber is allowed to settle for a period of 30 minutes before a reading is taken from the sensor. Prior to the sweep, the device is allowed to stabilize to 50%RH. The solid top and bottom trace in Figure 7, “Measuring Sensor Accuracy Including Hysteresis,” shows the result of a typical sweep after non-linearity compensation. RHAccuracyvs.RHSetͲPoint 5 4 Hysteresis 3 %RHAccuracy 2 1 0 Ͳ1 10 20 30 40 50 60 70 80 90 Ͳ2 Ͳ3 Ͳ4 Ͳ5 %RHSetͲpoint Figure 7. Measuring Sensor Accuracy Including Hysteresis Rev. 1.4 13 Si7005 The RH accuracy is defined as the center (dashed) line shown in Figure 7, which is the average of the two data points at each relative humidity set-point. In this case, the sensor shows an accuracy of 0.25%RH. The Si7005 accuracy specification (Table 4) includes: Unit-to-unit and lot-to-lot variation in non-linearity compensation of factory calibration Margin for shifts that can occur during solder reflow (compensation for shift due to reflow is included in the linearization procedure below). The accuracy specification does not include: Accuracy Hysteresis (typically ±1%) Effects from long term exposure to very humid conditions Contamination of the sensor by particulates, chemicals, etc. Other aging related shifts (“Long-term stability”) Variations due to temperature (a temperature compensation method is described in section “4.4. Temperature Compensation”). After application of temperature compensation, RH readings will typically vary by less than ±0.05%/°C. 14 Rev. 1.4 Si7005 4.3. Linearization Capacitive relative humidity sensors require linearization. The Si7005 accuracy specification (Table 4) applies after correction of non-linearity errors. The recommended linearization technique is to correct the measured relative humidity value with a 2nd order polynomial; the linear relative humidity (RH) value is calculated as follows: 2 RH Linear = RH Value – RH Value A 2 + RH Value A 1 + A 0 Where: RHLinear RHValue is the corrected relative humidity value in %RH is the uncorrected (measured) relative humidity value in %RH A2, A1, and A0 are unit-less correction coefficients derived through characterization of Si7005s by Silicon Laboratories; their values depend on whether compensation for a typical solder reflow is required The values for the correction coefficients are shown in Table 10. Table 10. Linearization Coefficients Coefficient Value A0 –4.7844 A1 0.4008 A2 –0.00393 Rev. 1.4 15 Si7005 4.4. Temperature Compensation The Si7005 relative humidity sensor is calibrated at a temperature of 30 °C; it is at this temperature that the sensor will give the most accurate relative humidity readings. For relative humidity measurements at other temperatures, the RH reading from the Si7005 must be compensated for the change in temperature relative to 30 °C. Temperature compensated relative humidity readings can be calculated as follows: RH TempCompensated = RH Linear + Temperature – 30 RH Linear Q 1 + Q 0 Where: RHTempCompensated RHLinear is the temperature compensated relative humidity value in %RH. is the linear corrected relative humidity value in %RH. Temperature is the ambient temperature in °C as measured by the Si7005 on chip temperature sensor. and Q0 are unit-less correction coefficients derived through characterization of Si7005s by Silicon Laboratories. This temperature compensation is most accurate in the range of 15–50 °C. The values for the correction coefficients are shown in Table 11. Q1 Table 11. Linearization Coefficients Coefficient Value Q0 0.1973 Q1 0.00237 4.5. Hysteresis The moisture absorbent film (polymeric dielectric) of the humidity sensor will carry a memory of its exposure history, particularly its recent or extreme exposure history. A sensor exposed to relatively low humidity will carry a negative offset relative to the factory calibration, and a sensor exposed to relatively high humidity will carry a positive offset relative to the factory calibration. This factor causes a hysteresis effect illustrated by the solid top and bottom traces in Figure 7. The hysteresis value is the difference in %RH between the maximum absolute error on the decreasing humidity ramp and the maximum absolute error on the increasing humidity ramp at a single relative humidity Setpoint and is expressed as a bipolar quantity relative to the average, the center dashed trace in Figure 7. In the case of Figure 7, the measurement uncertainty due to the hysteresis effect is ±1.05%RH. 4.6. Prolonged Exposure to High Humidity Prolonged exposure to high humidity will result in a gradual upward drift of the RH reading. The shift in sensor reading resulting from this drift will generally disappear slowly under normal ambient conditions. The amount of shift is proportional to the magnitude of relative humidity and the length of exposure. In the case of lengthy exposure to high humidity, some of the resulting shift may persist indefinitely under typical conditions. It is generally possible to substantially reverse this affect by baking the device (see section “4.9. Bake/Hydrate Procedure”). 16 Rev. 1.4 Si7005 4.7. PCB Assembly 4.7.1. Soldering Like most ICs, Si7005 devices are shipped from the factory vacuum-packed with an enclosed desiccant to avoid any drift during storage and to prevent any moisture-related issues during solder reflow. Devices should be soldered using reflow and a “no clean” solder process, as a water or solvent rinse after soldering may affect accuracy. See "11. PCB Land Pattern and Solder Mask Design" on page 34 for the recommended card reflow profile. It is essential that the exposed polymer sensing film be kept clean and undamaged. It is recommended that a protective cover of some kind be in place during PCB assembly. Kapton®* polyimide tape is recommended as a protective cover. See Table 12 below for examples of tape products that may be used for protection during the soldering operation. Alternatively, Si7005s may be ordered with a factory-fitted, solder-resistant protective cover that can be left in place for the lifetime of the product, preventing liquids, dust, or other contaminants from coming into contact with the polymer sensor film. See "9. Ordering Guide" on page 31 for a list of ordering part numbers that include the cover. 4.7.2. Rehydration The measured humidity value will generally shift slightly after solder reflow. A portion of this shift is permanent and is accounted for when using the linearization procedure given above. After soldering, an Si7005 should be allowed to equilibrate under controlled RH conditions (room temperature, 45–55%RH) for at least 48 hours to eliminate the remainder of the shift and return the device to its specified accuracy performance. 4.7.3. Rework To maintain the specified sensor performance, care must be taken during rework to minimize the exposure of the device to excessive heat and to avoid damage/contamination or a shift in the sensor reading due to liquids, solder flux, etc. Manual touch-up using a soldering iron is permissible under the following guidelines: The exposed polymer sensing film must be kept clean and undamaged. A protective cover is recommended during any rework operation (Kapton® tape or the factory-installed cover). Flux must not be allowed to contaminate the sensor; liquid flux is not recommended even with a cover in place. Conventional lead-free solder with rosin core is acceptable for touch-up as long as a cover is in place during the rework. Avoid water or solvent rinses after touch-up. Minimize the heating of the device. It is recommended that soldering iron temperatures not exceed 350 °C and that the contact time per pin does not exceed five seconds. Hot air rework is not recommended. If a device must be replaced, remove the device by hot air and solder a new part in its place by reflow following the guidelines above. *Note: All trademarks are the property of their respective owners. Table 12. Tape Products for Protection During Soldering Manufacturer Part Number* Manufacturer KPPD-1/8 Kaptontape.com *Note: Provided for information only. Figure 8. Si7005 with Factory-Installed Protective Cover Rev. 1.4 17 Si7005 4.8. Protecting the Sensor Because the sensor operates on the principal of measuring a change in capacitance, any changes to the dielectric constant of the polymer film will be detected as a change in relative humidity. Therefore, it is important to minimize the probability of contaminants coming into contact with the sensor. Dust and other particles as well as liquids can affect the RH reading. It is recommended that a cover is employed in the end system that blocks contaminants but allows water vapor to pass through. Depending on the needs of the application, this can be as simple as plastic or metallic gauze for basic protection against particulates or something more sophisticated such as a hydrophobic membrane providing up to IP67 compliant protection. The Si7005 may be ordered with a factory-fitted, solder-resistant cover that can be left in place for the lifetime of the product. It is very low-profile, hydrophobic and oleophobic. See Section “9. Ordering Guide” for a list of ordering part numbers that include the cover. A dimensioned drawing of the IC with the cover is included in Section “10. Package Outline”. Other characteristics of the cover are listed in the table below. Table 13. Specifications of Protective Cover Parameter Material Value PTFE Operating Temperature –40 to +125 °C Maximum Reflow Temperature IP Rating (per IEC 529) 260 °C IP67 4.9. Bake/Hydrate Procedure After exposure to extremes of temperature and/or humidity for prolonged periods, the polymer sensor film can become either very dry or very wet, in each case the result is either high or low relative humidity readings. Under normal operating conditions, the induced error will diminish over time. From a very dry condition, such as after shipment and soldering, the error will diminish over a few days at typical controlled ambient conditions, e.g., 48 hours of 45 ≤ %RH ≤ 55. However, from a very wet condition, recovery may take significantly longer. To accelerate recovery from a wet condition, a bake and hydrate cycle can be implemented. This operation consists of the following steps: the sensor at 125 °C for ≥ 12 hours at 30 °C in 75 %RH for ≥ 10 hours Following this cycle, the sensor will return to normal operation in typical ambient conditions after a few days. Baking Hydration 4.10. Long Term Drift/Aging Over long periods of time, the sensor readings may drift due to aging of the device. Standard accelerated life testing of the Si7005 has resulted in the specifications for long-term drift shown in Table 4 and Table 5. This contribution to the overall sensor accuracy accounts only for the long-term aging of the device in an otherwise benign operating environment and does not include the affects of damage, contamination, or exposure to extreme environmental conditions. 18 Rev. 1.4 Si7005 5. Host Interface 5.1. I2C Interface The Si7005 has an I2C serial interface with a 7-bit address of 0x40. The Si7005 is a slave device supporting data transfer rates up to 400 kHz. Table 24 shows the register summary of the Si7005. 5.1.1. Performing a Relative Humidity Measurement The following steps should be performed in sequence to take a relative humidity measurement: 1. Set START (D0) in CONFIG to begin a new conversion 2. Poll RDY (D0) in STATUS (register 0) until it is low (= 0) 3. Read the upper and lower bytes of the RH value from DATAh and DATAl (registers 0x01 and 0x02), respectively. Table 14 shows the format of the 12-bit relative humidity result. 4. Convert the RH value to %RH using the following equation: RH %RH = --------- – 24 16 where RH is the measured value returned in DATAh:DATAI 5. Apply temperature compensation and/or linearization as discussed elsewhere in this data sheet Table 15 shows the 12-bit values that correspond to various measured RH levels. Table 14. 12-Bit Relative Humidity Result Available in Registers 1 and 2 DATAh D7 D6 D5 D4 D3 DATAI D2 D1 D0 D7 D6 D5 12-Bit Relative Humidity Code D4 D3 D2 D1 D0 0 0 0 0 Table 15. Typical %RH Measurement Codes for 0 to 100% RH Range %RH 12 Bit Code Dec Hex 0 384 180 10 544 220 20 704 2C0 30 864 360 40 1024 400 50 1184 4A0 60 1344 540 70 1504 5E0 80 1664 680 90 1824 720 100 1984 7C0 The above sequence assumes normal mode, i.e., tCONV = 35 ms (typical). Conversions may be performed in fast mode. See section “5.1.3. Fast Conversion Mode”. Rev. 1.4 19 Si7005 5.1.2. Performing a Temperature Measurement The following steps should be performed in sequence to take a temperature measurement: 6. Set START (D0) and TEMP (D4) in CONFIG (register 0x03) to begin a new conversion, i.e., write CONFIG with 0x11 7. Poll RDY (D0) in STATUS (register 0) until it is low (=0) 8. Read the upper and lower bytes of the temperature value from DATAh and DATAl (registers 0x01 and 0x02), respectively Table 16 shows the format of the 14-bit temperature result. This value may be converted to °C using the following equation: TEMP Temperature C = ----------------- – 50 32 where TEMP is the measured value returned in DATAh:DATAI. Table 17 shows the 14-bit values that correspond to various measured temperature levels. Table 16. 14-Bit Temperature Result Available in Registers 1 and 2 DATAh D7 D6 D5 D4 D3 DATAI D2 D1 D0 D7 14-Bit Temperature Code D6 D5 D4 D3 D2 D1 D0 0 0 The above sequence assumes normal mode, i.e., tCONV = 35 ms (typical). Conversions may be performed in fast mode. See section “5.1.3. Fast Conversion Mode”. 20 Rev. 1.4 Si7005 Table 17. Typical Temperature Measurement Codes for the –40 °C to 100 °C Range Temp(°C) 14 Bit Code Dec Hex –40 320 0140 –30 640 0280 –20 960 03C0 –10 1280 0500 0 1600 0640 10 1920 0780 20 2240 08C0 30 2560 0A00 40 2880 0B40 50 3200 0C80 60 3520 0DC0 70 3840 0F00 80 4160 1040 90 4480 1180 100 4800 12C0 Rev. 1.4 21 Si7005 5.1.3. Fast Conversion Mode The time needed to perform a temperature or RH measurement can be reduced from 35 ms (typical) to 18 ms (typical) by setting FAST (D5) in CONFIG (register 0x03). Fast mode reduces the total power consumed during a conversion or the average power consumed by the Si7005 when making periodic conversions. It also reduces the resolution of the measurements. Table 18 is a comparison of the normal and fast modes. Table 18. Normal vs. Fast Mode Parameter Value Normal Mode Fast Mode tCONV (typical) 35 ms 18 ms Temperature resolution 14-bit 13-bit RH resolution 12-bit 11-bit 5.1.4. Heater The Si7005 relative humidity sensor contains an integrated, resistive heating element that may be used to raise the temperature of the humidity sensor. This element can be used to drive off condensation or to implement dew-point measurement when the Si7005 is used in conjunction with a separate temperature sensor such as another Si7005. The heater can be activated by setting HEAT (D1) in CONFIG (register 0x03). Turning on the heater will reduce the tendency of the humidity sensor to accumulate an offset due to “memory” of sustained high humidity conditions. When the heater is enabled, the reading of the on-chip temperature sensor will be affected (increased). 5.1.5. Device Identification The Si7005 device and its revision level can be determined by reading ID (register 0x11). Table 19 lists the values for the various device revisions and may include revisions not yet in existence. Table 19. Device ID Revision Values Device ID Value 22 D[7:4] D[3:0] 0101 0000 Rev. 1.4 Device Type Revision Level Si7005 B Si7005 5.2. I2C Operation The Si7005 uses a digital I2C interface. If the Si7005 shares an I2C bus with other slave devices, it should be powered down when the master controller is communicating with the other slave devices. The Si7005 can be powered down either by setting the CS signal to logic high or setting the VDD pin to 0 V. A method of achieving this by powering the Si7005 from an MCU GPIO is shown in Figure 5. The format of the address byte is shown in Table 20. Table 20. I2C Slave Address Byte A6 A5 A4 A3 A2 A1 A0 R/W 1 0 0 0 0 0 0 1/0 5.2.1. I2C Write Operation To write to a register on the Si7005, the master should issue a start command (S) followed by the slave address, 0x40. The slave address is followed by a 0 to indicate that the operation is a write. Upon recognizing its slave address, the Si7005 issues an acknowledge (A) by pulling the SDA line low for the high duration of the ninth SCL cycle. The next byte the master places on the bus is the register address pointer, selecting the register on the Si7005 to which the data should be transferred. After the Si7005 acknowledges this byte, the master places a data byte on the bus. This byte will be written to the register selected by the address pointer. The Si7005 will acknowledge the data byte, after which the master issues a Stop command (P). See Table 21. Master Slave Table 21. I2C Write Sequence Sequence to Write to a Register S Slave Address W A Address Pointer A Register Data A P A P A P Sequence to Start a Relative Humidity Conversion S 0x40 0 A 0x03 A 0x01 Sequence to Start a Temperature Conversion S 0x40 0 A 0x03 Rev. 1.4 A 0x11 23 Si7005 5.2.2. I2C Read Operation To read a register on the Si7005, the master must first set the address pointer to indicate the register from which the data is to be transferred. Therefore, the first communication with the Si7005 is a write operation. The master should issue a start command (S) followed by the slave address, 0x40. The slave address is followed by a 0 to indicate that the operation is a write. Upon recognizing its slave address, the Si7005 will issue an acknowledge (A) by pulling the SDA line low for the high duration of the ninth SCL cycle. The next byte the master places on the bus is the register address pointer selecting the register on the Si7005 from which the data should be transferred. After the Si7005 acknowledges this byte, the master issues a repeated start command (Sr) indicating that a new transfer is to take place. The Si7005 is addressed once again with the R/W bit set to 1, indicating a read operation. The Si7005 will acknowledge its slave address and output data from the previously-selected register onto the data bus under the control of the SCL signal, the master should not acknowledge (A) the data byte and issue a stop (P) command (see Table 22). However, if a RH or Temperature conversion result (two bytes) is to be read, the master should acknowledge (A) the first data byte and continue to activate the SCL signal. The Si7005 will automatically output the second data byte. Upon receiving the second byte, the master should issue a not Acknowledge (A) followed by a stop command. (See Table 23). Table 22. I2C Read Sequence for a Single Register Sequence to Read from a Single Register S Slave Address W A Address Pointer A Sr Slave Address R A Register Data A P 1 A ID A P 1 A A P Sequence to Read Device ID S 0x40 0 A 0x11 A Sr 0x40 Sequence to Read RDY bit S 0x40 0 0x00 A A Sr 0x40 — RDY Table 23. I2C Read Sequence for RH or Temperature Conversion Result Sequence to Read Conversion Result S Slave Address W A Address Pointer A Sr Slave Address R A Register 1 Data A Register 2 Data A P S 0x40 0 A 0x01 A Sr 0x40 1 A Data H A Data L A P 24 Rev. 1.4 Si7005 6. Si7005 Connection Diagrams The Si7005 is a simple-to-use device requiring a minimum of external components. Figure 9 shows the typical connection diagram for the Si7005 connected to an MCU. (Refer to section “8. Pin Descriptions: Si7005” for full pin descriptions). The values for the two I2C pull-up resistors depend on the capacitance of the I2C bus lines and the desired speed of operation. Refer to the I2C specification for further details. In this diagram CS is shown controlled by the MCU, allowing the Si7005 to be placed in standby mode when not in use. A detailed schematic and bill-ofmaterials for this circuit can be found in section “2. Typical Application Circuits” and section “3. Bill of Materials”. 2.1 to 3.6 V 0.1 µF VDD VDD Si7005 CEXT SCL SCL SDA SDA CS Px.x GND MCU C8051Fxxx 4.7µF GND Figure 9. Typical Connection Diagram For ultra-low-power operation, such as in battery-powered applications, connection as shown in Figure 10 is recommended. In this case, the Si7005 is powered from one of the MCU’s GPIOs. The GPIO can be driven high to powerup the Si7005, once the measurement results are obtained, the GPIO can be driven low to power-down the Si7005, reducing its current consumption to zero. The GPIO must be capable of sourcing 320 µA for the duration of the conversion time (<200 ms for relative humidity and temperature conversions) and up to 40 mA for a period of 5 ms at power-up. The GPIO must also be capable of sinking up to 40 mA for a period of 5 ms at powerdown. If the GPIO is not capable of sourcing/sinking 40 mA, then the Si7005 will take longer to powerup and powerdown. The purpose of the 15 resistor is to isolate the Si7005 from potential high-frequency switching noise present on the MCU GPIO. A detailed schematic and bill-of-materials for this circuit can be found in section “2. Typical Application Circuits” and section “3. Bill of Materials”. Rev. 1.4 25 Si7005 2.1 to 3.6 V VDD 15 Ohm Px.x 0.1 µF VDD Si7005 SCL SCL SDA SDA CS CEXT GND MCU C8051Fxxx 4.7µF GND Figure 10. Recommended Connection Diagram for Low-Power Battery Operation 26 Rev. 1.4 Si7005 7. Control Registers Table 24 contains a summary of the Si7005 register set. Each register is described in more detail below. Table 24. Si7005 Register Summary Register Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 RSVD RSVD RSVD /RDY I2C Register Summary 0 STATUS RSVD RSVD RSVD RSVD 1 DATAh Relative Humidity or Temperature, High Byte 2 DATAl Relative Humidity or Temperature, Low Byte 3 CONFIG RSVD RSVD FAST TEMP RSVD RSVD HEAT START 17 ID ID3 ID2 ID1 ID0 0 0 0 0 Notes: 1. Any register address not listed here is reserved and must not be written. 2. Reserved register bits (RSVD) must always be written as zero; the result of a read operation on these bits is undefined. 7.1. Register Detail (Defaults in Bold) Register 0. STATUS Bit D7 D6 D5 D4 D3 D2 D1 D0 Name /RDY Type R Reset Settings = 0000_0001 Bit 7:1 0 Name Function Reserved Reserved. Reads undefined. /RDY Ready. 0 = conversion complete; results available in DATAh:DATAl. 1 = conversion in progress. Rev. 1.4 27 Si7005 Register 1. DATAh Bit D7 D6 D5 D4 D3 D2 Name Relative Humidity or Temperature, High Byte Type R D1 D0 Reset Settings = 0000_0000 Bit Name 7:0 DATAh Function Data, High Byte. Eight most significant bits of a temperature or humidity measurement. See Table 14 or Table 16 for the measurement format. Register 2. DATAI Bit D7 D6 D5 D4 D3 D2 Name Relative Humidity or Temperature, Low Byte Type Read D1 D0 Reset Settings = 0000_0000 28 Bit Name 7:0 DATAl Function Data, Low Byte. Eight least significant bits of a temperature or humidity measurement. See Table 14 or Table 16 for the measurement format. Rev. 1.4 Si7005 Register 3. CONFIG Bit D7 D6 D5 D4 Name FAST TEMP Type R/W R/W D3 D2 D1 D0 HEAT START R/W Reset Settings = 0000_0000 Bit 7:6 Name Function Reserved Reserved. Reads undefined. Always write as zero. 5 FAST Fast Mode Enable. 0 = 35 ms (typical) 1 = 18 ms (typical) 4 TEMP Temperature Enable. 0 = Relative humidity 1 = Temperature 3:2 Reserved Reserved. Reads undefined. Always write as zero. 1 HEAT Heater Enable. 0 = heater off 1 = heater on 0 START Conversion Start. 0 = do not start a conversion 1 = start a conversion Register 17. ID Bit D7 D6 D5 D4 D3 D2 D1 D0 Name ID7 ID6 ID5 ID4 ID3 ID2 ID1 ID0 Type R R R R R R R R Reset Settings = 0101_0000 Bit Name 7:0 ID Function Identification. See section “5.1.5. Device Identification”. Rev. 1.4 29 Si7005 DNC DNC DNC DNC DNC GND 24 23 22 21 20 19 8. Pin Descriptions: Si7005 DNC 5 14 DNC DNC 6 13 DNC 12 15 CS DNC 4 11 SDA GND 16 DNC 10 3 CEXT SCL 9 17 DNC VDD 2 8 DNC GND 18 DNC 7 1 DNC GND Table 25. Pin Descriptions Pin # Pin Name Pin Type* 1, 8, 11, 19 GND G 2, 5–7, 12–14, 16–18, 20–24 DNC 3 SCL Description Ground. Do Not Connect. Do not connect any of these pins to supply, ground or any other signal. Internal pull-ups or pull-downs will prevent any of these pins from floating. I I2C Clock Signal. This pin is voltage-tolerant. See Table 2. 4 SDA I/O I2C Data Signal. This pin is voltage-tolerant. See Table 2. 9 VDD S VDD Power Supply (2.1 V < VDD < 3.6 V). 10 CEXT I Decoupling Input for Internal Circuitry. Connect a 4.7 µF capacitor between this pin and GND. 15 CS I Chip Select—Active Low Signal. Epad TGND G Thermal Paddle. This pad is connected to GND internally. The pad can be connected to GND externally or it can be left open-circuit and used as a thermal input to the on-chip temperature sensor. *Note: G = Ground, S = Power Supply, I = Digital Input, O = Digital Output, I/O = Input/Output. 30 Rev. 1.4 Si7005 9. Ordering Guide Table 26. Si7005 Device Ordering Guide Typ. Accuracy P/N Description Temp RH Pkg Operating Range (°C) Filter Cover Packing Format Si7005-B-FM1 Digital temperature/humidity sensor ±0.5 °C ±3% QFN-24 0 to 70 °C Y Cut Tape Si7005-B-GM1 Digital temperature/humidity sensor ±0.5 °C ±3% QFN-24 –40 to +85 °C Y Cut Tape Si7005-B-FMR Digital temperature/humidity sensor ±0.5 °C ±3% QFN-24 0 to 70 °C N Tape-and-reel Si7005-B-FM1R Digital temperature/humidity sensor ±0.5 °C ±3% QFN-24 0 to 70 °C Y Tape-and-reel Si7005-B-GMR Digital temperature/humidity sensor ±0.5 °C ±3% QFN-24 –40 to +85 °C N Tape-and-reel Si7005-B-GM1R Digital temperature/humidity sensor ±0.5 °C ±3% QFN-24 –40 to +85 °C Y Tape-and-reel Si7005-B-FM Digital temperature/humidity sensor ±0.5 °C ±3% QFN-24 0 to 70 °C N Tube Si7005-B-GM Digital temperature/humidity sensor ±0.5 °C ±3% QFN-24 –40 to +85 °C N Tube Si7005USBDONGLE USB demonstration/evaluation board Si7005-EVB Si7005 daughter card with flex cable Si7005EVB-UDP Si7005 UDP plug-in daughter card Si7005EVBUDP-F960 Low-power data logger demo/development kit with C8051F960 MCU Rev. 1.4 31 Si7005 10. Package Outline 10.1. 24-Pin QFN Figure 11 illustrates the package details for the Si7005. Tables 27 and 28 list the values for the dimensions shown in the illustration. There are two package variants with slightly different height dimensions. The two package variants are otherwise interchangeable. Figure 11. 24-Pin Quad Flat No Lead (QFN) Table 27. 24-Pin Package Diagram Dimensions Dimension Min Nom Max Dimension Min Nom Max A1 0.00 0.02 0.05 H1 1.03 1.08 1.13 b 0.18 0.25 0.30 H2 D D2 4.00 BSC. 2.55 2.65 2.75 1.68 REF L 0.30 0.35 0.40 aaa — — 0.15 e 0.50 BSC. bbb — — 0.15 E 4.00 BSC. ccc — — 0.08 ddd — — 0.10 E2 2.55 2.65 2.75 Notes: 1. Dimensioning and Tolerancing per ANSI Y14.5M-1994. 2. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. Table 28. Package Variants Variant A Variant B Dimension Min Nom Max Min Nom Max A 0.80 0.90 1.00 0.70 0.75 0.80 Note: All Dimensions are in mm unless otherwise noted. 32 Rev. 1.4 Si7005 10.2. 24-Pin QFN with Protective Cover Figure 12 illustrates the package details for the Si7005 with the optional protective cover. Tables 29 and 30 list the values for the dimensions shown in the illustration. There are two package variants with slightly different height dimensions. The two package variants are otherwise interchangeable. Figure 12. 24-Pin Quad Flat No Lead (QFN) With Protective Cover Table 29. 24-Pin Package Diagram Dimensions Dimension Min Nom Max Dimension Min Nom Max A1 0.00 0.02 0.05 h 0.76 0.83 0.90 b 0.18 025 0.30 L 0.30 0.35 0.40 R1 0.45 0.50 0.55 D D2 4.00 BSC. aaa — — 0.15 e 2.55 0.50 BSC. 2.65 2.75 bbb — — 0.15 E 4.00 BSC. ccc — — 0.08 ddd — — 0.10 E2 2.55 2.65 2.75 F1 3.60 3.75 3.90 F2 3.60 3.75 3.90 Notes: 1. Dimensioning and Tolerancing per ANSI Y14.5M-1994. 2. Recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. Table 30. Package Variants Variant A Variant B Dimension Min Nom Max Min Nom Max A — 1.27 1.41 — 1.07 1.21 A2 0.80 0.90 1.00 0.70 0.75 0.80 Note: All Dimensions are in mm unless otherwise noted. Rev. 1.4 33 Si7005 11. PCB Land Pattern and Solder Mask Design Figure 13 illustrates the recommended PCB land pattern for use with the Si7005's 4x4 mm QFN package. Figure 13. Typical QFN-24 PCB Land Pattern 34 Rev. 1.4 Si7005 Table 31. PCB Land Pattern Dimensions Symbol mm C1 4.00 C2 4.00 E 0.50 P1 2.75 P2 2.75 X1 0.30 Y1 0.75 Notes: General 1. All dimensions shown are at Maximum Material Condition (MMC). Least Material Condition (LMC) is calculated based on a Fabrication Allowance of 0.05 mm. 2. This Land Pattern Design is based on the IPC-7351 guidelines. Solder Mask Design 3. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal pad is to be 60m minimum, all the way around the pad. Stencil Design 4. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good solder paste release. 5. The stencil thickness should be 0.125 mm (5 mils). 6. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pins. 7. A 2x2 array of 0.95 mm square openings on 1.35 mm pitch should be used for the center ground pad. Card Assembly 8. A No-Clean, Type-3 solder paste is recommended. 9. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components. Rev. 1.4 35 Si7005 12. Top Marking TTTT 12.1. Si7005 Top Marking 7005 YYWW 12.2. Top Marking Explanation Location Marking Explanation Upper Left 7005 Part Number Upper Right TTTT Manufacturing trace code Lower Left (Dot) Pin 1 Identifier Lower Right YYWW Manufacturing date code YY = year WW = week Note: The top mark may not be visible if the optional protective cover is installed. If needed, the device can be identified by reading the identification register as explained in section “5.1.5. Device Identification”. 36 Rev. 1.4 Si7005 13. Additional Reference Resources Si7005USB Dongle User’s Guide Si7005EVB-UDP User's Guide AN607: Si70xx Humidity Sensor Designer’s Guide Rev. 1.4 37 Si7005 DOCUMENT CHANGE LIST Added Linearization Coefficients Table 10,11 Updated Host Interface Revision 0.1 to Revision 0.2 Updated I2C Operation Amended Connection Diagram Amended Ordering Guide Expanded Additional Reference Resources Updated Table 2, “General Specifications*,” on page 4. Updated Table 4, “Humidity Sensor,” on page 7. New Note 1. Revision 1.0 to Revision 1.1 Added Table 6, “Thermal Characteristics,” on page 9. Updated Table 7, “Absolute Maximum Ratings1,2,” on page 9. max value for “Voltage on SDA or SCL pin with respect to GND” parameter. Clarified Updated Figure 2 on page 7. Updated Figure 3 on page 8. Updated "2.1.1. Steps to Perform Relative Humidity Measurement" on page 9. Updated Table 12, “14-Bit Temperature Result Available in Registers 1 and 2,” on page 10. Revised Added "2.1.6. RSVD" on page 11. Updated "2.2. I2C Operation" on page 12. Updated Table 22, “I2C Read Sequence for a Single Register,” on page 24. Updated Table 23, “I2C Read Sequence for RH or Temperature Conversion Result,” on page 24. Revision 0.2 to Revision 0.9 Updated Features/Applications/Description Added pinout drawing to front page Updated Electrical Specifications Clarified voltage tolerance of CS, SDA, and SCL pins Updated Typical Application Circuits and BOMs Updated and expanded Functional Description Updated Host Interface Updated register descriptions Added drawing and photo of device with cover Updated and expanded Ordering Guide Expanded Additional Reference Resources Updated “4.7 Soldering” to “4.7. PCB Assembly”. Updated Table 19, “Device ID Revision Values,” on page 22. Corrected 38 title. Revision 1.1 to Revision 1.2 Updated Table 4, “Humidity Sensor,” on page 7. Updated typical response time. Updated Table 7, “Absolute Maximum Ratings1,2,” on page 9. Added ESD tolerance specs. Revision 1.2 to Revision 1.3 Added nominal values to Dimension A in Table 30 Revision 1.3 to Revision 1.4 Revision 0.9 to Revision 1.0 with black and white version. title. RH and temperature accuracy graphs. Updated Figure 7. Replaced Updated Updated Figures 2 and 3. Updated and expanded General Specification Table 2 Updated and expanded General Specification Table 3 Updated Figure 1. Updated Figure 2. Updated Bill of Materials Rev. 1.4 Minor modification to description and dimensions of protective cover due to the addition of a second cover supplier. Smart. Connected. Energy-Friendly. Products Quality Support and Community www.silabs.com/products www.silabs.com/quality community.silabs.com Disclaimer Silicon Laboratories intends to provide customers with the latest, accurate, and in-depth documentation of all peripherals and modules available for system and software implementers using or intending to use the Silicon Laboratories products. Characterization data, available modules and peripherals, memory sizes and memory addresses refer to each specific device, and "Typical" parameters provided can and do vary in different applications. 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