Si 7 0 2 0 - A2 0
I
2
C H
UMIDITY A N D
T
EMPERATURE
S
ENSOR
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
Up to –40 to +125 °C operating
range
Wide operating voltage
(1.9 to 3.6 V)
Low Power Consumption
150 µA active current
60 nA standby current
Factory-calibrated
I
2
C Interface
Integrated on-chip heater
3x3 mm DFN Package
Excellent long term stability
Optional factory-installed cover
Low-profile
Protection during reflow
Excludes liquids and particulates
Ordering Information:
See page 29.
Applications
Pin Assignments
Micro-environments/data centers
Automotive climate control and
defogging
Asset and goods tracking
Mobile phones and tablets
HVAC/R
Thermostats/humidistats
Respiratory therapy
White goods
Indoor weather stations
Top View
SDA
GND
DNC
1
2
3
6
5
4
SCL
VDD
DNC
Description
The Si7020 I
2
C Humidity and Temperature Sensor is a monolithic CMOS IC
integrating humidity and temperature sensor elements, an analog-to-digital
converter, signal processing, calibration data, and an I
2
C Interface. The patented
use of industry-standard, low-K polymeric dielectrics for sensing humidity enables
the construction of low-power, monolithic CMOS Sensor ICs with low drift and
hysteresis, and excellent long term stability.
The humidity and temperature sensors are factory-calibrated and the calibration
data is stored in the on-chip non-volatile memory. This ensures that the sensors
are fully interchangeable, with no recalibration or software changes required.
The Si7020 is available in a 3x3 mm DFN package and is reflow solderable. It can
be used as a hardware- and software-compatible drop-in upgrade for existing RH/
temperature sensors in 3x3 mm DFN-6 packages, featuring precision sensing
over a wider range and lower power consumption. The optional factory-installed
cover offers a low profile, convenient means of protecting the sensor during
assembly (e.g., reflow soldering) and throughout the life of the product, excluding
liquids (hydrophobic/oleophobic) and particulates.
The Si7020 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.
Patent Protected. Patents pending
Rev. 1.2 8/16
Copyright © 2016 by Silicon Laboratories
Si7020-A20
Si7020-A20
Functional Block Diagram
Vdd
Si7020
Humidity
Sensor
1.25V
Ref
Calibration
Memory
Control Logic
ADC
Temp
Sensor
I
2
C Interface
SDA
SCL
GND
2
Rev. 1.2
Si7020-A20
T
ABLE O F
C
ONTENTS
Section
Page
1. Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2. Typical Application Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3. Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.1. Relative Humidity Sensor Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.2. Hysteresis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.3. Prolonged Exposure to High Humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.4. PCB Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.5. Protecting the Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.6. Bake/Hydrate Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.7. Long Term Drift/Aging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5. I2C Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.1. Issuing a Measurement Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.2. Reading and Writing User Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.3. Electronic Serial Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
5.4. Firmware Revision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.5. Heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
6. Control Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
6.1. Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
7. Pin Descriptions: Si7020 (Top View) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
8. Ordering Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
9. Package Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
9.1. Package Outline: 3x3 6-pin DFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
9.2. Package Outline: 3x3 6-pin DFN with Protective Cover . . . . . . . . . . . . . . . . . . . . . . 31
10. PCB Land Pattern and Solder Mask Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
11. Top Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
11.1. Si7020 Top Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
11.2. Top Marking Explanation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
12. Additional Reference Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Document Change List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
Rev. 1.2
3
Si7020-A20
1. Electrical Specifications
Unless otherwise specified, all min/max specifications apply over the recommended operating conditions.
Table 1. Recommended Operating Conditions
Parameter
Power Supply
Operating Temperature
Operating Temperature
Symbol
V
DD
T
A
T
A
I and Y grade
G grade
Test Condition
Min
1.9
–40
–40
Typ
—
—
—
Max
3.6
+125
+85
Unit
V
°C
°C
Table 2. General Specifications
1.9 < V
DD
< 3.6 V; T
A
= –40 to 85 °C (G grade) or –40 to 125 °C (I/Y grade); default conversion time unless otherwise noted.
Parameter
Input Voltage High
Input Voltage Low
Input Voltage Range
Input Leakage
Output Voltage Low
Symbol
V
IH
V
IL
V
IN
I
IL
V
OL
Test Condition
SCL, SDA pins
SCL, SDA pins
SCL, SDA pins with respect to GND
SCL, SDA pins
SDA pin; I
OL
= 2.5 mA; V
DD
= 3.3 V
SDA pin; I
OL
= 1.2 mA;
V
DD
= 1.9 V
Min
0.7xV
DD
—
0.0
—
—
—
—
—
—
—
—
—
—
Typ
—
—
—
—
—
—
150
90
0.06
0.06
3.5
3.5
3.1 to 94.2
Max
—
0.3xV
DD
V
DD
1
0.6
0.4
180
120
0.62
3.8
4.0
4.0
—
Unit
V
V
V
μA
V
V
μA
μA
μA
μA
mA
mA
mA
Current
Consumption
I
DD
RH conversion in progress
Temperature conversion in progress
Standby, –40 to +85 °C
2
Standby, –40 to +125 °C
2
Peak IDD during powerup
3
Peak IDD during I
2
C operations
4
Heater Current
5
I
HEAT
Notes:
1.
Initiating a RH measurement will also automatically initiate a temperature measurement. The total conversion time will
be t
CONV
(RH) + t
CONV
(T).
2.
No conversion or I
2
C transaction in progress. Typical values measured at 25 °C.
3.
Occurs once during powerup. Duration is <5 msec.
4.
Occurs during I
2
C commands for Reset, Read/Write User Registers, Read EID, and Read Firmware Version. Duration is
<100 µs when I
2
C clock speed is >100 kHz (>200 kHz for 2-byte commands).
5.
Additional current consumption when HTRE bit enabled. See Section “5.5. Heater” for more information.
4
Rev. 1.2
Si7020-A20
Table 2. General Specifications (Continued)
1.9 < V
DD
< 3.6 V; T
A
= –40 to 85 °C (G grade) or –40 to 125 °C (I/Y grade); default conversion time unless otherwise noted.
Parameter
Conversion Time
1
Symbol
t
CONV
Test Condition
12-bit RH
11-bit RH
10-bit RH
8-bit RH
14-bit temperature
13-bit temperature
12-bit temperature
11-bit temperature
Min
—
—
—
—
—
—
—
—
—
—
—
Typ
10
5.8
3.7
2.6
7
4
2.4
1.5
18
—
5
Max
12
7
4.5
3.1
10.8
6.2
3.8
2.4
25
80
15
Unit
ms
Powerup Time
t
PU
From V
DD
≥
1.9 V to ready for a
conversion, 25 °C
From V
DD
≥
1.9 V to ready for a
conversion, full temperature range
After issuing a software reset
command
ms
Notes:
1.
Initiating a RH measurement will also automatically initiate a temperature measurement. The total conversion time will
be t
CONV
(RH) + t
CONV
(T).
2.
No conversion or I
2
C transaction in progress. Typical values measured at 25 °C.
3.
Occurs once during powerup. Duration is <5 msec.
4.
Occurs during I
2
C commands for Reset, Read/Write User Registers, Read EID, and Read Firmware Version. Duration is
<100 µs when I
2
C clock speed is >100 kHz (>200 kHz for 2-byte commands).
5.
Additional current consumption when HTRE bit enabled. See Section “5.5. Heater” for more information.
Rev. 1.2
5
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