SI7005-B-FMR [SILICON]
DIGITAL I2C HUMIDITY AND TEMPERATURE SENSOR;
| 型号： | SI7005-B-FMR |
| 厂家： | 
SILICON |
| 描述： | DIGITAL I2C HUMIDITY AND TEMPERATURE SENSOR |
| 文件： | 总41页 (文件大小：340K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Si7005
DIGITAL I2C HUMIDITY AND TEMPERATURE SENSOR
Features
2
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
I C host interface
Integrated on-chip heater
4x4 mm QFN package
Excellent long term stability
Factory calibrated
Optional factory-installed
–40 to +85 °C (GM) or 0 to +70 °C
cover
Low-profile
Protection during reflow
Excludes liquids and
particulates
operating range (FM)
Wide operating voltage range
Ordering Information
(2.1 to 3.6 V)
See Ordering Guide.
Low Power Consumption
240 µA during RH conversion
(hydrophobic/oleophobic)
Patent protected; patents pending
Applications
Pin Assignments
Industrial HVAC/R
Thermostats/humidistats
Respiratory therapy
White goods
Micro-environments/data centers
Automotive climate control and
de-fogging
Asset and goods tracking
1
2
3
4
5
6
18 DNC
17 DNC
GND
DNC
Description
DNC
CS
16
15
14
13
SCL
SDA
DNC
DNC
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
DNC
DNC
2
data, and an I C 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.
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 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 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. 1.2 1/14
Copyright © 2014 by Silicon Laboratories
Si7005
Si7005
Functional Block Diagram
VDD
VDD
NV CAL
VDD
32 kHz Osc
Humidity
Sensor
CEXT
SCL
PXx
PXy
PXz
I2C
Serial
IF
Logic
MUX
ADC
SDA
CS
Temperature
Sensor
GND
Microcontroller
Si7005
2
Rev. 1.2
Si7005
TABLE OF CONTENTS
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
2
5.1. I C Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
2
5.2. I C 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
Rev. 1.2
3
Si7005
1. Electrical Specifications
Unless otherwise specified, all min/max specifications apply over the recommended operating conditions.
Table 1. Recommended Operating Conditions
Symbol
Test Condition
Min
2.1
–40
0
Typ
3.3
—
Max
3.6
85
Unit
V
Parameter
Power Supply
V
DD
Operating Temperature
Operating Temperature
T
G grade
F grade
°C
°C
A
T
—
70
A
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
Input Voltage High
Input Voltage Low
Input Voltage Range
Symbol
Test Condition
CS, SCL, SDA pins
CS, SCL, SDA pins
Min
Typ
Max
Unit
V
V
0.7xV
—
—
—
—
—
IH
DD
V
0.3xV
V
IL
DD
V
SCL, SDA pins with respect
to GND
0.0
3.6
V
IN
CS, C
pin with respect to
GND
0.0
—
V
V
EXT
DD
Input Leakage
I
CS, SCL, SDA pins
—
—
—
—
±1
µA
V
IL
Output Voltage Low
V
SDA pin; I = 8.5 mA;
0.6
OL
OL
V
= 3.3 V
DD
SDA pin; I = 3.5 mA;
—
—
0.4
V
OL
V
= 2.1 V
DD
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. 1.2
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
Symbol
Test Condition
Min
—
Typ
240
320
Max
Unit
µA
Power Consumption
I
RH conversion in progress
560
565
DD
Temperature conversion in
progress
—
µA
Average for 1 temperature
and 1 RH conversion /
minute
—
—
1
—
—
µA
µA
CS < V ; no conversion in
150
IL
progress; V = 3.3 V;
DD
SDA = SCL ≥ V
IH
CS > V
—
—
—
100
31
µA
IH
CS < V ; no conversion in
24
IL
progress; V = 3.3 V;
mA
DD
SDA = SCL ≥ V ; HEAT = 1
IH
Conversion Time
t
14-bit temperature; 12-bit RH
(Fast = 0)
35
18
10
10
40
21
15
15
CONV
ms
13-bit temperature; 11-bit RH
(Fast = 1)
Wake Up Time
Power Up Time
Notes:
t
t
From CS < VIL to ready for a
temp/RH conversion
ms
ms
CS
PU
From V ≥ 2.1V to ready for
DD
a temp/RH conversion
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. 1.2
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
Hysteresis
Symbol
Test Condition
Min
Typ
Max
Unit
V
High-to-low versus low-to- 0.05 x V
high transition
—
—
V
HYS
DD
SCLK Frequency
SCL high time
f
—
—
—
—
—
—
—
—
—
—
—
—
400
—
kHz
µs
µs
µs
µs
µs
µs
ns
ns
µs
µs
SCL
t
0.6
1.3
0.6
0.6
0.6
SKH
SCL low time
t
—
SKL
Start hold time
t
—
STH
Start setup time
Stop setup time
Bus free time
t
—
STS
SPS
BUF
t
t
—
Between Stop and Start
1.3
100
100
—
—
SDA setup time
SDA hold time
t
—
DS
t
—
DH
SDA valid time
SDA acknowledge valid time
t
From SCL low to data valid
From SCL low to data valid
0.9
0.9
VD;DAT
VD;ACK
t
—
*Note: All values are referenced to VIL and/or VIH.
tSKH
tSKL
1/fSCL
SCL
tBUF
tSTH
tDS
tDH
tSPS
D7
D6
D5
D0
R/W
ACK
SDA
Start Bit
tSTS
Stop Bit
tVD
:
ACK
2
Figure 1. I C Interface Timing Diagram
6
Rev. 1.2
Si7005
Table 4. Humidity Sensor
2.1 VDD 3.6 V; TA = 25 °C; tCONV = 35 ms unless otherwise noted.
Parameter
Symbol
Test Condition
Min
0
Typ
Max
Unit
%RH
bit
1
Operating Range
Non-condensing
—
—
100
12
2
Resolution
—
—
3,4
Accuracy
20–80% RH
0–100% RH
±3.0
±4.5
%RH
See Figure 2
0.05
Repeatability—Noise
—
—
%RH
RMS
5
Response Time
63%
1 m/s airflow
—
—
—
18
±1
—
—
—
s
Hysteresis
%RH
4
Long Term Stability
0.25
%RH/yr
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.
RHꢀAccuracy
Max.ꢀRHꢀErrorꢀ( %)
Typ.ꢀRHꢀErrorꢀ( %)
10
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
RelativeꢀHumidityꢀ(%)
Figure 2. RH Accuracy at 30 °C
Rev. 1.2
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
–40
—
Typ
Max
85
Unit
°C
Operating Range
—
1
Resolution
—
14
Bit
°C
—
—
±0.5
1/32
±1.0
2
Accuracy
Typical at 25 °C
Maximum
—
°C
See Figure 3.
0.1
°C
Repeatability—Noise
—
—
°C
RMS
3
Response Time
Time to reach 63% of final value
—
—
1.5
—
—
s
Long Term Stability
<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.
TemperatureꢀAccuracy
Max.ꢀTꢀErrorꢀ(°C)
Typ.ꢀTꢀErrorꢀ(°C)
4
3.5
3
2.5
2
1.5
1
0.5
0
Temperatureꢀ(°C)
Figure 3. Temperature Accuracy
8
Rev. 1.2
Si7005
Table 6. Thermal Characteristics
Symbol
Test Condition
QFN-24
Unit
°C/W
°C/W
Parameter
Junction-to-Air Thermal Resistance
Junction-to-Air Thermal Resistance
JEDEC 4-layer board
55
JA
2-layer evaluation PCB with
minimal thermal pad
110
JA
Table 7. Absolute Maximum Ratings1,2
Symbol
Test Condition
Min
–55
–65
–0.3
Typ
—
Max
Unit
°C
°C
V
Parameter
Ambient Temperature under Bias
Storage Temperature
125
150
3.9
—
Voltage on SDA or SCL pin with
respect to GND
—
Voltage on CS pin with respect to
GND
–0.3
—
VDD + 0.3
V
Voltage on V with respect to GND
–0.3
—
—
—
—
—
4.2
3
V
kV
V
DD
ESD Tolerance
HBM
CDM
MM
—
750
300
—
V
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. 1.2
9
Si7005
2. Typical Application Circuits
Note: If the Si7005 shares an I2C bus with other slave devices, it should be powered down when the master controller is com-
municating 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).
VDD
1
2
3
4
5
6
18
17
16
15
14
13
GND
DNC
SCL
SDA
DNC
DNC
DNC
DNC
DNC
CS
R1
10K
R2
10K
U1
SCL
SDA
Si7005
DNC
DNC
CSb
C1
4.7uF
C2
0.1uF
GND
Figure 4. Typical Application Circuit
VDD
R3
15.0
1
Port Pin
18
17
16
15
14
13
GND
DNC
DNC
DNC
CS
R1
10K
R2
2
3
4
5
6
10K
DNC
SCL
SDA
DNC
DNC
U2
SCL
SDA
Si7005
DNC
DNC
C1
4.7uF
C2
0.1uF
GND
Figure 5. Typical Application Circuit for Battery-Powered Applications
Rev. 1.2
10
Si7005
3. Bill of Materials
Table 8. Typical Application Circuit BOM
Reference
Description
Mfr Part Number
Manufacturer
Venkel
C1
C2
Capacitor, 4.7 µF, 6.3 V, X5R, 0603
Capacitor, 0.1 µF, 6.3 V, X7R, 0603
Resistor, 10 k, ±5%, 1/16W, 0603
Resistor, 10 k, ±5%, 1/16W, 0603
IC, digital temperature/humidity sensor
C0603X5R6R3-475M
C0603X7R6R3-104M
CR0603-16W-1002J
CR0603-16W-1002J
Si7005
Venkel
*
R1
R2
Venkel
*
Venkel
U1
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
C0805X5R160-475M
C0603X7R6R3-104M
CR0603-16W-1002J
CR0603-16W-1002J
CR0603-16W-15R0J
Si7005
Manufacturer
Venkel
C1
C2
Capacitor, 4.7 µF, 6.3 V, X5R, 0805
Capacitor, 0.1 µF, 6.3 V, X7R, 0603
Resistor, 10 k, ±5%, 1/16W, 0603
Resistor, 10 k, ±5%, 1/16W, 0603
Resistor, 15 , ±5%, 1/16W, 0603
IC, digital temperature/humidity sensor
Venkel
*
R1
Venkel
*
R2
Venkel
R3
U1
Venkel
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. 1.2
11
Si7005
4. Functional Description
VDD
VDD
NV CAL
VDD
32 kHz Osc
Humidity
Sensor
CEXT
SCL
SDA
CS
PXx
PXy
PXz
I2C
Serial
IF
Logic
MUX
ADC
Temperature
Sensor
GND
Microcontroller
Si7005
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
2
and humidity sensor elements, an analog-to-digital converter, signal processing, calibration data, and an I C 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. 1.2
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.
Hysteresis
Figure 7. Measuring Sensor Accuracy Including Hysteresis
Rev. 1.2
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
Accuracy 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:
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. 1.2
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:
RHLinear = RHValue – RHValue2 A2 + RHValue A1 + A0
Where:
RH
RH
is the corrected relative humidity value in %RH
Linear
Value
is the uncorrected (measured) relative humidity value in %RH
A , A , and A are unit-less correction coefficients derived through characterization of Si7005s by Silicon
2
1
0
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
–4.7844
0.4008
A
A
A
0
1
2
–0.00393
Rev. 1.2
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:
RHTempCompensated = RHLinear + Temperature – 30 RHLinear Q1 + Q0
Where:
RH
RH
is the temperature compensated relative humidity value in %RH.
TempCompensated
is the linear corrected relative humidity value in %RH.
Linear
Temperature is the ambient temperature in °C as measured by the Si7005 on chip temperature sensor.
Q and Q are unit-less correction coefficients derived through characterization of Si7005s by Silicon
1
0
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.
Table 11. Linearization Coefficients
Coefficient
Value
0.1973
0.00237
Q
Q
0
1
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. 1.2
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*
KPPD-1/8
Manufacturer
Kaptontape.com
*Note: Provided for information only.
Figure 8. Si7005 with Factory-Installed Protective Cover
Rev. 1.2
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 filter 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.
Si7005s may be ordered with a factory fitted, solder-resistant cover, which can be left in place for the lifetime of the
product. It is very low-profile, hydrophobic and oleophobic, and excludes particulates down to 0.35 microns in size.
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
Table 13. The sensor should be protected from direct sunlight to prevent heating effects as well as possible
material degradation.
Table 13. Specifications of Protective Cover
Parameter
Value
ePTFE
2.7 bar
0.35µ
Material
Water Entry Pressure
Pore Size
Operating Temperature
Maximum Reflow Temperature
Oleophobicity (AATCC 118 – 1992)
IP Rating (per IEC 529)
–40 to +125 °C
260 °C
7
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:
Baking the sensor at 125 °C for ≥ 12 hours
Hydration 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.
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. 1.2
Si7005
5. Host Interface
2
5.1. I C Interface
2
The Si7005 has an I C 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
D4 D3
12-Bit Relative Humidity Code
DATAI
D4 D3
D7
D6
D5
D2
D1
D0
D7
D6
D5
D2
D1
D0
0
0
0
0
Table 15. Typical %RH Measurement Codes for 0 to 100% RH Range
%RH
12 Bit Code
Dec
384
Hex
180
220
2C0
360
400
4A0
540
5E0
680
720
7C0
0
10
20
30
40
50
60
70
80
90
100
544
704
864
1024
1184
1344
1504
1664
1824
1984
The above sequence assumes normal mode, i.e., t
mode. See section “5.1.3. Fast Conversion Mode”.
= 35 ms (typical). Conversions may be performed in fast
CONV
Rev. 1.2
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
32
-----------------
TemperatureC =
– 50
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
D4 D3
DATAI
D4 D3
D7
D6
D5
D2
D1
D0
D7
D6
D5
D2
D1
D0
14-Bit Temperature Code
0
0
The above sequence assumes normal mode, i.e., t
mode. See section “5.1.3. Fast Conversion Mode”.
= 35 ms (typical). Conversions may be performed in fast
CONV
20
Rev. 1.2
Si7005
Table 17. Typical Temperature Measurement Codes for the –40 °C to 100 °C Range
Temp(°C)
14 Bit Code
Dec
320
Hex
0140
0280
03C0
0500
0640
0780
08C0
0A00
0B40
0C80
0DC0
0F00
1040
1180
12C0
–40
–30
–20
–10
0
640
960
1280
1600
1920
2240
2560
2880
3200
3520
3840
4160
4480
4800
10
20
30
40
50
60
70
80
90
100
Rev. 1.2
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
18 ms
t
(typical)
35 ms
14-bit
12-bit
CONV
Temperature resolution
RH resolution
13-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
Device
Type
Revision
Level
D[7:4]
0101
D[3:0]
0000
Si7005
B
22
Rev. 1.2
Si7005
2
5.2. I C Operation
2
2
The Si7005 uses a digital I C interface. If the Si7005 shares an I C 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
2
5.2.1. I C 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
S
S
Slave Address
W
A
Address Pointer
A
Register Data
A
A
A
P
P
P
Sequence to Start a Relative Humidity Conversion
0x03 0x01
0x40
0x40
0
A
A
Sequence to Start a Temperature Conversion
0
A
0x03
A
0x11
Rev. 1.2
23
Si7005
2
5.2.2. I C 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
S
S
Slave Address
W
0
A
A
A
Address Pointer
A
Sr Slave Address
R
1
1
A
A
A
Register Data
A
A
A
P
P
P
Sequence to Read Device ID
0x11 Sr 0x40
0x40
A
ID
Sequence to Read RDY bit
0x00 Sr 0x40
0x40
0
A
—
RDY
Table 23. I2C Read Sequence for RH or Temperature Conversion Result
Sequence to Read Conversion Result
S
S
Slave
Address
W
A
Address
Pointer
A
Sr
Slave
Address
R
A
Register 1
Data
A
Register 2
Data
A
A
P
P
0x40
0
A
0x01
A
Sr
0x40
1
A
Data H
A
Data L
24
Rev. 1.2
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
2
2
descriptions). The values for the two I C pull-up resistors depend on the capacitance of the I C bus lines and the
2
desired speed of operation. Refer to the I C 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-of-
materials 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
SCL
SDA
CS
SCL
Si7005
SDA
Px.x
CEXT
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. 1.2
25
Si7005
2.1 to 3.6 V
VDD
15 Ohm
0.1 µF
Px.x
VDD
SCL
SDA
CS
SCL
SDA
Si7005
CEXT
GND
MCU
C8051Fxxx
4.7µF
GND
Figure 10. Recommended Connection Diagram for Low-Power Battery Operation
26
Rev. 1.2
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
2
I C Register Summary
0
STATUS
DATAh
DATAl
CONFIG
ID
RSVD RSVD RSVD RSVD RSVD RSVD
RSVD
/RDY
1
2
Relative Humidity or Temperature, High Byte
Relative Humidity or Temperature, Low Byte
3
RSVD RSVD FAST TEMP RSVD RSVD
ID3 ID2 ID1 ID0
HEAT START
17
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
/RDY
R
Name
Type
Reset Settings = 0000_0001
Bit
7:1
0
Name
Reserved Reserved. Reads undefined.
/RDY Ready.
Function
0 = conversion complete; results available in DATAh:DATAl.
1 = conversion in progress.
Rev. 1.2
27
Si7005
Register 1. DATAh
Bit
D7
D6
D5
D4
D3
D2
D1
D0
Name
Type
Relative Humidity or Temperature, High Byte
R
Reset Settings = 0000_0000
Bit
Name
Function
7:0
DATAh
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
D1
D0
Name
Relative Humidity or Temperature, Low Byte
Read
Type
Reset Settings = 0000_0000
Bit
Name
Function
7:0
DATAl
Data, Low Byte.
Eight least significant bits of a temperature or humidity measurement. See Table 14 or
Table 16 for the measurement format.
28
Rev. 1.2
Si7005
Register 3. CONFIG
Bit
D7
D6
D5
D4
D3
D2
D1
D0
START
R/W
Name
Type
FAST
R/W
TEMP
R/W
HEAT
Reset Settings = 0000_0000
Bit
7:6
5
Name
Function
Reserved Reserved. Reads undefined. Always write as zero.
FAST
Fast Mode Enable.
0 = 35ms (typical)
1 = 18ms (typical)
4
TEMP
Temperature Enable.
0 = Relative humidity
1 = Temperature
3:2
1
Reserved Reserved. Reads undefined. Always write as zero.
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
ID7
R
D6
ID6
R
D5
ID5
R
D4
ID4
R
D3
ID3
R
D2
ID2
R
D1
ID1
R
D0
ID0
R
Name
Type
Reset Settings = 0101_0000
Bit
Name
Function
7:0
ID
Identification.
See section “5.1.5. Device Identification”.
Rev. 1.2
29
Si7005
8. Pin Descriptions: Si7005
1
18 DNC
GND
DNC
DNC
DNC
CS
2
3
4
5
6
17
16
15
14
13
SCL
SDA
DNC
DNC
DNC
DNC
Table 25. Pin Descriptions
Pin #
Pin Name
GND
Pin Type*
Description
1, 8, 11, 19
G
Ground.
2, 5–7, 12–14,
16–18, 20–24
DNC
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.
2
3
4
SCL
SDA
I
I C Clock Signal.
This pin is voltage-tolerant. See Table 2.
2
I/O
I C Data Signal.
This pin is voltage-tolerant. See Table 2.
9
V
S
I
V
Power Supply (2.1 V < V < 3.6 V).
DD DD
DD
10
C
Decoupling Input for Internal Circuitry.
EXT
Connect a 4.7 µF capacitor between this pin and GND.
15
CS
I
Chip Select—Active Low Signal.
Thermal Paddle.
Epad
T
G
GND
This pad is connected to GND internally. The pad can be con-
nected 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. 1.2
Si7005
9. Ordering Guide
Table 26. Si7005 Device Ordering Guide
Typ. Accuracy
Pkg
Operating
Range (°C)
Filter
Cover
Packing
Format
P/N
Description
Temp
RH
Si7005-B-FM1
Si7005-B-GM1
Si7005-B-FMR
Digital temperature/humidity sensor ±0.5 °C ±3% QFN-24
0 to 70 °C
Y
Y
N
Y
N
Y
N
N
Cut Tape
Cut Tape
Digital temperature/humidity sensor ±0.5 °C ±3% QFN-24 –40 to +85 °C
Digital temperature/humidity sensor ±0.5 °C ±3% QFN-24
0 to 70 °C
0 to 70 °C
Tape-and-reel
Tape-and-reel
Tape-and-reel
Tape-and-reel
Tube
Si7005-B-FM1R Digital temperature/humidity sensor ±0.5 °C ±3% QFN-24
Si7005-B-GMR Digital temperature/humidity sensor ±0.5 °C ±3% QFN-24 –40 to +85 °C
Si7005-B-GM1R Digital temperature/humidity sensor ±0.5 °C ±3% QFN-24 –40 to +85 °C
Si7005-B-FM
Si7005-B-GM
Digital temperature/humidity sensor ±0.5 °C ±3% QFN-24
0 to 70 °C
Digital temperature/humidity sensor ±0.5 °C ±3% QFN-24 –40 to +85 °C
USB demonstration/evaluation board
Tube
Si7005USB-
DONGLE
Si7005-EVB
Si7005 daughter card with flex cable
Si7005EVB-UDP Si7005 UDP plug-in daughter card
Si7005EVB-
UDP-F960
Low-power data logger demo/devel-
opment kit with C8051F960 MCU
Rev. 1.2
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
0.00
0.18
Nom
0.02
Max
0.05
0.30
Dimension
Min
Nom
1.08
1.68 REF
0.35
—
Max
A1
H1
H2
L
1.03
1.13
b
D
0.25
4.00 BSC.
2.65
0.30
—
0.40
0.15
0.15
0.08
D2
2.55
2.55
2.75
2.75
aaa
bbb
ccc
e
0.50 BSC.
4.00 BSC.
2.65
—
—
E
—
—
E2
—
—
ddd
0.10
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
Nom
Variant B
Nom
Dimension
Min
Max
Min
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. 1.2
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
0.00
0.18
Nom
0.02
Max
0.05
0.30
Dimension
Min
0.76
0.30
0.45
—
Nom
0.83
0.35
0.50
—
Max
0.90
0.40
0.55
0.15
0.15
0.08
0.10
A1
h
b
D
025
L
4.00 BSC.
2.65
R1
aaa
bbb
ccc
D2
e
2.55
2.75
0.50 BSC.
4.00 BSC.
2.65
—
—
E
—
—
E2
2.55
3.70
3.70
2.75
3.90
3.90
—
—
ddd
F1
3.80
F2
3.80
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
Nom
—
Variant B
Nom
—
Dimension
Min
—
Max
1.41
1.00
Min
—
Max
1.21
0.80
A
A2
0.80
0.90
0.70
0.75
Note: All Dimensions are in mm unless otherwise noted.
Rev. 1.2
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. 1.2
Si7005
Table 31. PCB Land Pattern Dimensions
Symbol
mm
4.00
4.00
0.50
2.75
2.75
0.30
0.75
C1
C2
E
P1
P2
X1
Y1
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. 1.2
35
Si7005
12. Top Marking
12.1. Si7005 Top Marking
7005
YYWW
12.2. Top Marking Explanation
Location
Marking
Explanation
Upper Left
7005
Part Number
Upper Right
Lower Left
Lower Right
TTTT
(Dot)
Manufacturing trace code
Pin 1 Identifier
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. 1.2
Si7005
13. Additional Reference Resources
Si7005USB Dongle User’s Guide
Si7005EVB-UDP User's Guide
AN607: Si70xx Humidity Sensor Designer’s Guide
Rev. 1.2
37
Si7005
Added Linearization Coefficients Table 10,11
Updated Host Interface
DOCUMENT CHANGE LIST
Revision 0.1 to Revision 0.2
2
Updated I C Operation
Updated Table 2, “General Specifications*,” on
Amended Connection Diagram
Amended Ordering Guide
page 4.
Updated Table 4, “Humidity Sensor,” on page 7.
Expanded Additional Reference Resources
New Note 1.
Revision 1.0 to Revision 1.1
Added Table 6, “Thermal Characteristics,” on
Updated Figures 2 and 3.
page 9.
1 2
Clarified RH and temperature accuracy graphs.
Updated Figure 7.
Updated Table 7, “Absolute Maximum Ratings , ,”
on page 9.
Replaced with black and white version.
Updated “4.7 Soldering” to “4.7. PCB Assembly”.
Updated max value for “Voltage on SDA or SCL pin with
respect to GND” parameter.
Updated Table 19, “Device ID Revision Values,” on
Updated Figure 2 on page 7.
Updated Figure 3 on page 8.
page 22.
Corrected title.
Updated "2.1.1. Steps to Perform Relative Humidity
Measurement" on page 9.
Revision 1.1 to Revision 1.2
Updated Table 12, “14-Bit Temperature Result
Available in Registers 1 and 2,” on page 10.
Revised title.
Updated Table 4, “Humidity Sensor,” on page 7.
Updated typical response time.
1 2
Updated Table 7, “Absolute Maximum Ratings , ,”
Added "2.1.6. RSVD" on page 11.
on page 9.
Added ESD tolerance specs.
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
Revision 0.9 to Revision 1.0
Updated and expanded General Specification
Table 2
Updated and expanded General Specification
Table 3
Updated Figure 1.
Updated Figure 2.
Updated Bill of Materials
38
Rev. 1.2
Si7005
NOTES:
Rev. 1.2
39
Si7005
CONTACT INFORMATION
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40
Rev. 1.2
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