Si7022 Data Sheet

Si 7 0 2 2 - A20
H U MI D I T Y / TEMPERATURE S ENSOR WITH P W M O UTPUT
Features






Precision Relative Humidity Sensor
 ± 4% RH (max), 0–80% RH
High Accuracy Temperature Sensor
±0.4 °C (max), –10 to 85 °C
0 to 100% RH operating range
–40 to +125 °C operating range
Wide operating voltage
(1.9 to 3.6 V)
Low Power Consumption

Factory-calibrated
PWM Output
 3x3 mm DFN Package
 Excellent long term stability
 Optional factory-installed cover
Low-profile
Protection during reflow
Excludes liquids and particulates

Applications





HVAC/R
Thermostats/humidistats
Respiratory therapy
White goods
Indoor weather stations

Micro-environments/data centers
 Automotive climate control and
defogging
 Asset and goods tracking
 Mobile phones and tablets
Ordering Information:
See page 18.
Pin Assignments
Description
Top View
The Si7022 Humidity and Temperature Sensor is a monolithic CMOS IC
integrating humidity and temperature sensor elements, an analog-to-digital
converter, signal processing, calibration data, and a PWM output. The PWM
output may be filtered to produce an analog voltage output. The patented use of
industry-standard, low-K polymeric dielectrics for sensing humidity enables the
construction of low-power, monolithic CMOS Sensor ICs with low drift and
hysteresis, and excellent long term stability.
The humidity and temperature sensors are factory-calibrated and the calibration
data is stored in the on-chip non-volatile memory. This ensures that the sensors
are fully interchangeable, with no recalibration or software changes required.
The Si7022 is available in a 3x3 mm DFN package and is reflow solderable. It can
be used as a hardware- and software-compatible drop-in upgrade for existing RH/
temperature sensors in 3x3 mm DFN-6 packages, featuring precision sensing
over a wider range and lower power consumption. The optional factory-installed
cover offers a low profile, convenient means of protecting the sensor during
assembly (e.g., reflow soldering) and throughout the life of the product, excluding
liquids (hydrophobic/oleophobic) and particulates.
PWM1
1
6
SELECT
GND
2
5
VDD
DNC
3
4
PWM2
Patent Protected. Patents pending
The Si7022 offers an accurate, low-power, factory-calibrated digital solution ideal
for measuring humidity, dew-point, and temperature, in applications ranging from
HVAC/R and asset tracking to industrial and consumer platforms.
Rev. 1.2 2/16
Copyright © 2016 by Silicon Laboratories
Si7022-A20
Si7022-A20
Functional Block Diagram
Vdd
Si7022
Humidity
Sensor
1.25V
Ref
Calibration
Memory
Control Logic
ADC
SELECT
Temp
Sensor
PWM Interface
PWM1
PWM2
GND
2
Rev. 1.2
Si7022-A20
TABLE O F C ONTENTS
Section
Page
1. Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2. Typical Application Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
3. Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1. Relative Humidity Sensor Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.2. Hysteresis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.3. Prolonged Exposure to High Humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.4. PCB Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.5. Protecting the Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.6. Bake/Hydrate Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.7. Long Term Drift/Aging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5. PWM Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6. Pin Descriptions: Si7022 (Top View) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7. Ordering Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8. Package Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.1. Package Outline: 3x3 6-pin DFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.2. Package Outline: 3x3 6-pin DFN with Protective Cover . . . . . . . . . . . . . . . . . . . . . . 20
9. PCB Land Pattern and Solder Mask Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
10. Top Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
10.1. Si7022 Top Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
10.2. Top Marking Explanation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
11. Additional Reference Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Document Change List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Rev. 1.2
3
Si7022-A20
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
Operating Temperature
Test Condition
Min
Typ
Max
Unit
VDD
1.9
—
3.6
V
TA
–40
—
+125
°C
Table 2. General Specifications
1.9 < VDD < 3.6 V; TA = –40 to 125 °C unless otherwise noted.
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
Input Voltage High
VIH
SELECT pin
0.7xVDD
—
—
V
Input Voltage Low
VIL
SELECT pin
—
—
0.3xVDD
V
Input Voltage Range
VIN
SELECT pin with respect to GND
0.0
—
VDD
V
Input Leakage
IIL
SELECT pin
—
—
1
μA
VOH
PWM1, PWM2 pins, IOH = –10 μA
VDD – 0.1
—
—
V
PWM1, PWM2 pins pin,
IOH = –0.5 mA, VDD = 2.0 V
VDD – 0.2
—
—
PWM1, PWM2 pins,
IOH = –1.7 mA, VDD = 3.0 V
VDD – 0.4
—
—
PWM1, PWM2 pins; IOL = 2.5 mA;
VDD = 3.3 V
—
—
0.6
V
PWM1, PWM2 pins; IOL = 1.2 mA;
VDD = 1.9 V
—
—
0.4
V
RH and Temperature
—
2
—
Hz
μA
Output Voltage High
Output Voltage Low
VOL
Sample Rate
Current
Consumption
IDD
Average Current
—
150
300
Powerup Time
tPU
From VDD ≥ 1.9 V to PWM output
enabled, 25 °C
—
48
55
From VDD ≥ 1.9 V to PWM output
enabled, full temperature range
—
—
110
4
Rev. 1.2
ms
Si7022-A20
Table 3. PWM Interface Specifications
1.9  VDD  3.6 V; TA = –40 to +125 °C unless otherwise noted.
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
1.00
1.22
1.40
kHz
PWM Frequency
FPWM
PWM Duty Cycle
DCPWM
tH / tPWM
0
—
1
tSS
From SELECT transition to
PWM valid
—
500
—
SELECT Setup Time
ms
tPWM
tH
tSS
RH Data
Temperature Data
Figure 1. PWM Interface Timing Diagram
Rev. 1.2
5
Si7022-A20
Table 4. Humidity Sensor
1.9 ≤ VDD ≤ 3.6 V; TA = 30 °C
Parameter
Operating
Accuracy
Symbol
Range1
2, 3
Test Condition
Min
Typ
Max
Unit
Non-condensing
0
—
100
%RH
0 – 80% RH
—
±3
±4
%RH
80 – 100% RH
See Figure 2.
Repeatability/Noise
—
0.025
—
%RH RMS
Resolution
—
11
—
Bits
—
6
—
S
Drift vs. Temperature
—
0.05
—
%RH/°C
Hysteresis
—
±1
—
%RH
—
< 0.25
—
%RH/yr
Response Time
Long Term
4
τ63%
1 m/s airflow, with or without
cover
Stability3
Notes:
1. Recommended humidity operating range is 20% to 80% RH (non-condensing) over –10 °C to 60 °C. Prolonged
operation beyond these ranges may result in a shift of sensor reading, with slow recovery time.
2. Excludes hysteresis, long term drift, and certain other factors and is applicable to non-condensing environments only.
See Section “4.1. Relative Humidity Sensor Accuracy” for more details.
3. Drift due to aging effects at typical room conditions of 30 °C and 30% to 50% RH. May be impacted by dust, vaporized
solvents or other contaminants, e.g., out-gassing tapes, adhesives, packaging materials, etc. See Section “4.7. Long
Term Drift/Aging” .
4. Response time to a step change in RH. Time for the RH output to change by 63% of the total RH change.
Figure 2. RH Accuracy at 30 °C
6
Rev. 1.2
Si7022-A20
Table 5. Temperature Sensor
1.9 ≤ VDD ≤ 3.6 V; TA = –40 to +125 °C unless otherwise noted.
Parameter
Symbol
Test Condition
Operating Range
Min
Typ
Max
Unit
–40
—
+125
°C
—
±0.3
±0.4
°C
–10 °C< tA < 85 °C
Accuracy
–40 < tA < 125 °C
Figure 3.
Repeatability/Noise
—
0.04
—
°C RMS
Resolution
—
11
—
Bits
Unmounted device
—
0.7
—
s
Si7022-EB board
—
5.1
—
—
 0.01
—
Response Time*
τ63%
Long Term Stability
°C/Yr
*Note: Time to reach 63% of final value in response to a step change in temperature. Actual response time will vary
dependent on system thermal mass and air-flow.
Figure 3. Temperature Accuracy
Rev. 1.2
7
Si7022-A20
Table 6. Thermal Characteristics
Parameter
Symbol
Test Condition
DFN-6
Unit
Junction to Air Thermal Resistance
JA
JEDEC 2-Layer board,
No Airflow
256
°C/W
Junction to Air Thermal Resistance
JA
JEDEC 2-Layer board,
1 m/s Airflow
224
°C/W
Junction to Air Thermal Resistance
JA
JEDEC 2-Layer board,
2.5 m/s Airflow
205
°C/W
Junction to Case Thermal Resistance
JC
JEDEC 2-Layer board
22
°C/W
Junction to Board Thermal Resistance
JB
JEDEC 2-Layer board
134
°C/W
Table 7. Absolute Maximum Ratings1
Parameter
Min
Typ
Max
Unit
Ambient temperature
under bias
–55
—
125
°C
Storage Temperature2
–65
—
150
°C
Voltage on I/O pins
–0.3
—
VDD+0.3 V
V
Voltage on VDD with
respect to GND
–0.3
—
4.2
V
HBM
—
—
2
kV
CDM
—
—
1.25
kV
MM
—
—
250
V
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. Special handling considerations apply; see application note, “AN607: Si70xx Humidity Sensor Designer’s Guide”.
8
Rev. 1.2
Si7022-A20
2. Typical Application Circuits
The primary function of the Si7022 is to measure relative humidity and temperature. Figure 4 demonstrates the
typical application circuit to achieve these functions.
1.9 V to 3.6 V
C1
0.1 µF
5
SELECT
6
VDD
Si7022
PWM1
R1
100 k 
1
VRH/VTEMP
C2
1 µF
SELECT
PWM2
4
VTEMP/VRH
R2
100 k 
GND
C3
1 µF
2
Optional
U1
Figure 4. Typical Application Circuit for Relative Humidity and Temperature Measurement
Rev. 1.2
9
Si7022-A20
3. Bill of Materials
Table 8. Typical Application Circuit BOM for Relative Humidity and Temperature Measurement
Reference
Description
Mfr Part Number
Manufacturer
C1
Capacitor, 0.1 μF, 16 V, X7R, 0603
Various
Various
R1
Resistor, 100 k, ±5%, 1/16W, 0603
Various
Various
C2
Capacitor, 1 μF, 16 V, X7R, 0603
Various
Various
R2
Resistor, 100 k, ±5%, 1/16W, 0603 (optional)
Various
Various
C3
Capacitor, 1 μF, 16 V, X7R, 0603 (optional)
Various
Various
U1
IC, Digital Temp/Humidity Sensor
Si7022-A20
Silicon Labs
10
Rev. 1.2
Si7022-A20
4. Functional Description
Vdd
Si7022
Humidity
Sensor
1.25V
Ref
Calibration
Memory
Control Logic
ADC
SELECT
Temp
Sensor
PWM Interface
PWM1
PWM2
GND
Figure 5. Si7022 Block Diagram
The Si7022 is a digital relative humidity and temperature sensor that integrates temperature and humidity sensor
elements, an analog-to-digital converter, signal processing, calibration, polynomial non-linearity correction, and a
PWM output all in a single chip. The Si7022 is individually factory-calibrated for both temperature and humidity,
with the calibration data stored in on-chip, non-volatile memory. This ensures that the sensor is fully
interchangeable, with no recalibration or changes to software required. Patented use of industry-standard CMOS
and low-K dielectrics as a sensor enables the Si7022 to achieve excellent long term stability and immunity to
contaminants with low drift and hysteresis. The Si7022 offers a low-power, high-accuracy, calibrated and stable
solution ideal for a wide range of temperature, humidity, and dew-point applications including medical and
instrumentation, high-reliability automotive and industrial systems, and cost-sensitive consumer electronics.
While the Si7022 is largely a conventional mixed-signal CMOS integrated circuit, relative humidity sensors in
general and those based on capacitive sensing using polymeric dielectrics 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 senor from damage or contamination during the product life-cycle.
The impact of prolonged exposure to extremes of temperature and/or humidity and their potential effect on
sensor accuracy.
The effects of humidity sensor “memory”.
Each of these items is discussed in more detail in the following sections.
Rev. 1.2
11
Si7022-A20
4.1. 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 25–30 °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 60 minutes before a reading is taken from the
sensor. Prior to the sweep, the device is allowed to stabilize to 50%RH. The solid trace in Figure 6, “Measuring
Sensor Accuracy Including Hysteresis,” shows the result of a typical sweep.
Figure 6. Measuring Sensor Accuracy Including Hysteresis
The RH accuracy is defined as the dotted line shown in Figure 6, 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 Si7022 accuracy
specification (Table 4) includes:
Unit-to-unit
and lot-to-lot variation
of factory calibration
Margin for shifts that can occur during solder reflow
The accuracy specification does not include:
Accuracy
Hysteresis
(typically ±1%)
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 (see Drift vs. Temperature in Table 4). RH readings will typically vary with
temperature by less than  0.05%  C.
Effects
12
Rev. 1.2
Si7022-A20
4.2. 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 trace
in Figure 6. 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 error (dashed trace). In the example of
Figure 6, the measurement uncertainty due to the hysteresis effect is ±1.0%RH.
4.3. 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 effect by baking the device (see Section “4.6. Bake/Hydrate Procedure” ).
4.4. PCB Assembly
4.4.1. Soldering
Like most ICs, Si7022 devices are shipped from the factory vacuum-packed with an enclosed desiccant to avoid
any RH accuracy drift during storage and to prevent any moisture-related issues during solder reflow. The following
guidelines should be observed during PCB assembly:
Si7022
devices are compatible with standard board assembly processes. Devices should be soldered
using reflow per the recommended card reflow profile. See Section “9. PCB Land Pattern and Solder Mask
Design” for the recommended card reflow profile.
A "no clean" solder process is recommended to minimize the need for water or solvent rinses after
soldering. Cleaning after soldering is possible, but must be done carefully to avoid impacting the
performance of the sensor. See “AN607: Si70xx Humidity Sensor Designer’s Guide” for more information
on cleaning.
It is essential that the exposed polymer sensing film be kept clean and undamaged. This can be
accomplished by careful handling and a clean, well-controlled assembly process. When in doubt or for
extra protection, a heat-resistant, protective cover such as Kapton™ KPPD-1/8 polyimide tape can be
installed during PCB assembly.
Si7022s may be ordered with a factory-fitted, solder-resistant protective cover. This cover provides protection
during PCB assembly or rework but without the time and effort required to install and remove the Kapton tape. It
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 Section “7. Ordering Guide” for a list of ordering part numbers that
include the cover.
Rev. 1.2
13
Si7022-A20
4.4.2. Rehydration
The measured humidity value will generally shift slightly after solder reflow. A portion of this shift is permanent and
is accounted for in the accuracy specifications in Table 4. After soldering, an Si7022 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.
4.4.3. 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.
If possible, avoid water or solvent rinses after touch-up. Cleaning after soldering is possible, but must be
done carefully to avoid impacting the performance of the sensor. See “AN607: Si70xx Humidity Sensor
Designer’s Guide” for more information on cleaning.
Minimize the heating of the device. Soldering iron temperatures should not exceed 350 °C and the contact
time per pin should 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.
Figure 7. Si7022 with Factory-Installed Protective Cover
14
Rev. 1.2
Si7022-A20
4.5. 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 Si7022 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 “7. 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 “8.
Package Outline” . Other characteristics of the cover are listed in Table 9.
Table 9. Specifications of Protective Cover
Parameter
Value
Material
PTFE
Operating Temperature
–40 to 125 °C
Maximum Reflow Temperature
IP Rating (per IEC 529)
260 °C
IP67
4.6. 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
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.
Baking
4.7. 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 Si7022 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 effects of damage, contamination, or exposure to extreme
environmental conditions.
Rev. 1.2
15
Si7022-A20
5. PWM Output
During operation, the Si7022 takes a relative humidity and temperature measurement once per second and
converts the result into a pulse width modulated waveform. Two output pins are available for reading the
measurement results: PWM1 and PWM2. The information output on each pin is determined by the SELECT pin as
follows:
Table 10. PWM Outputs
Voltage on SELECT Pin
PWM1 Output
PWM2 Output
High
RH
Temperature
Low
Temperature
RH
The duty cycle of the waveform on the PWM outputs corresponds to the relative humidity and temperature results
shown in the following equations. The PWM duty cycle varies linearly with the measurement result between the
minimum and maximum values:
RH (%RH) = – 6 + 125  DC PWM
Where DC PWM is the ratio of high time to period (i.e., a number that varies from 0 to 1)
Equation 1.
T(°C) = – 46.85 + 175.72  DC PWM
Equation 2.
In the typical application, the PWM output is filtered using an RC network to provide an analog output voltage that
varies linearly with RH and temperature. See Section “2. Typical Application Circuits” for the recommended
application circuit.
Due to normal variations in RH accuracy of the device as described in Table 4, it is possible for the measured value
of %RH to be slightly less than 0 when the actual RH level is close to or equal to 0. Similarly, the measured value
of %RH may be slightly greater than 100 when the actual RH level is close to or equal to 100. This is expected
behavior.
16
Rev. 1.2
Si7022-A20
6. Pin Descriptions: Si7022 (Top View)
PWM1
1
6
SELECT
GND
2
5
VDD
DNC
3
4
PWM2
Pin Name
Pin #
Pin Description
PWM1
1
Pulse width modulated output #1
GND
2
Ground. This pin is connected to ground on the circuit board through a trace. Do not
connect directly to GND plane.
DNC
3
This pin should be soldered to pads on the PCB for mechanical stability. It can be
electrically floating or tied to VDD (do not tie to GND).
PWM2
4
Pulse width modulated output #2
VDD
5
Power. This pin is connected to power on the circuit board.
SELECT
6
Digital input that toggles between RH and temperature outputs on PWM1 and PWM2.
This pin should be pulled high or low (do not leave floating).
TGND
Paddle
This pad is connected to GND internally. This pad is the main thermal input to the onchip temperature sensor. The paddle should be soldered to a floating pad.
Rev. 1.2
17
Si7022-A20
7. Ordering Guide
Table 11. Device Ordering Guide
P/N
Description
Max.
Accuracy
Temp
Si7022-A20-IM
Pkg
Operating
Range (°C)
Protective
Cover
Packing
Format
RH
Digital temperature/ humidity sensor – ±0.4 °C
industrial temp range
± 4%
DFN 6
–40 to +125 °C
N
Tube
Si7022-A20-IMR
Digital temperature/ humidity sensor –
industrial temp range
±0.4 °C
± 4%
DFN 6
–40 to +125 °C
N
Tape &
Reel
Si7022-A20-IM1
Digital temperature/ humidity sensor –
industrial temp range
±0.4 °C
± 4%
DFN 6
–40 to +125 °C
Y
Cut Tape
Si7022-A20-IM1R
Digital temperature/ humidity sensor –
industrial temp range
±0.4 °C
± 4%
DFN 6
–40 to +125 °C
Y
Tape &
Reel
Si7022-A20-YM0
Digital temperature/ humidity sensor –
automotive
±0.4 °C
± 4%
DFN 6
–40 to +125 °C
N
Tube
Si7022-A20-YM0R
Digital temperature/ humidity sensor –
automotive
±0.4 °C
± 4%
DFN 6
–40 to +125 °C
N
Tape &
Reel
Si7022-A20-YM1
Digital temperature/ humidity sensor –
automotive
±0.4 °C
± 4%
DFN 6
–40 to +125 °C
Y
Cut Tape
Si7022-A20-YM1R
Digital temperature/ humidity sensor –
automotive
±0.4 °C
± 4%
DFN 6
–40 to +125 °C
Y
Tape &
Reel
Note: The “A” denotes product revision A and “20” denotes firmware version 2.0.
18
Rev. 1.2
Si7022-A20
8. Package Outline
8.1. Package Outline: 3x3 6-pin DFN
Figure 10. 3x3 6-pin DFN
Table 12. 3x3 6-pin DFN Package Diagram Dimensions
Dimension
Min
Nom
Max
A
0.70
0.75
0.80
A1
0.00
0.02
0.05
b
0.35
0.40
0.45
D
D2
3.00 BSC.
1.40
1.50
e
1.00 BSC.
E
3.00 BSC.
1.60
E2
2.30
2.40
2.50
H1
0.85
0.90
0.95
H2
1.39
1.44
1.49
L
0.35
0.40
0.45
aaa
0.10
bbb
0.10
ccc
0.05
ddd
0.10
eee
0.05
fff
0.05
Notes:
1. All dimensions shown are in millimeters (mm).
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
Rev. 1.2
19
Si7022-A20
8.2. Package Outline: 3x3 6-pin DFN with Protective Cover
Figure 8 illustrates the package details for the Si7022 with the optional protective cover. Table 13 lists the values
for the dimensions shown in the illustration.
Figure 8. 3x3 6-pin DFN with Protective Cover
Table 13. 3x3 6-pin DFN with Protective Cover Package Diagram Dimensions
Dimension
A
A1
A2
b
D
D2
e
E
E2
F1
F2
h
L
R1
aaa
bbb
ccc
ddd
eee
Min
—
0.00
0.70
0.35
1.40
2.30
2.70
2.70
0.76
0.35
0.45
Nom
—
0.02
0.75
0.40
3.00 BSC.
1.50
1.00 BSC.
3.00 BSC.
2.40
2.80
2.80
0.83
0.40
0.50
0.10
0.10
0.05
0.10
0.05
Max
1.21
0.05
0.80
0.45
1.60
2.50
2.90
2.90
0.90
0.45
0.55
Notes:
1. All dimensions are shown in millimeters (mm).
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
20
Rev. 1.2
Si7022-A20
9. PCB Land Pattern and Solder Mask Design
Figure 9. Si7022 PCB Land Pattern
Table 14. PCB Land Pattern Dimensions
Symbol
mm
C1
2.90
E
1.00
P1
1.60
P2
2.50
X1
0.45
Y1
0.85
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 60 µm 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 2x1 array of 1.00 mm square openings on 1.30 mm pitch should be used for the
center ground pad to achieve a target solder coverage of 50%.
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
21
Si7022-A20
10. Top Marking
10.1. Si7022 Top Marking
10.2. Top Marking Explanation
22
Mark Method:
Laser
Font Size
0.30 mm
Pin 1 Indicator:
Circle = 0.30 mm Diameter
Upper-Left Corner
Line 1 Marking:
TTTT = Mfg Code
Rev. 1.2
Si7022-A20
11. Additional Reference Resources
AN607:
Si70xx Humidity Sensor Designer’s Guide
Rev. 1.2
23
Si7022-A20
DOCUMENT CHANGE LIST
Revision 0.9 to Revision 1.0


Updated Table 2.
Updated Table 3.
Revision 1.0 to Revision 1.1

Updated Section “4.5. Protecting the Sensor”
 Updated Table 9
 Updated Table 13 dimensions F1 and F2
Revision 1.1 to Revision 1.2
 Updated PWM Duty Cycle parameter in Table 3 on
page 5.
 Updated Equation 1 and Equation 2 on page 16.
24
Rev. 1.2
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