S i7013-A 2 0
I 2 C H U M I D I T Y A N D TW O -Z O N E TE M P E R A T U R E S E N S O R
Features
Precision Relative Humidity Sensor
± 3% RH (max), 0–80% RH
High Accuracy Temperature Sensor
±0.4 °C (max), –10 to 85 °C
0 to 100% RH operating range
Up to –40 to +125 °C operating
range
Low Voltage Operation (1.9 to 3.6 V)
Low Power Consumption
150 μA active current
60 nA standby current
Factory-calibrated
I2C Interface
Integrated on-chip heater
Auxiliary Sensor input
Direct readout of remote
thermistor temperature in °C
Package: 3x3 mm DFN
Excellent long term stability
Optional factory-installed cover
Low-profile
Protection during reflow
Excludes liquids and particulates
Pin Assignments
Applications
HVAC/R
Thermostats/humidistats
Instrumentation
White goods
Ordering Information:
See page 38.
Micro-environments/data centers
Industrial Controls
Indoor weather stations
Top View
Description
The Si7013 I2C Humidity and 2-Zone Temperature Sensor is a monolithic CMOS
IC integrating humidity and temperature sensor elements, an analog-to-digital
converter, signal processing, calibration data, and an I2C Interface. The patented
use of industry-standard, low-K polymeric dielectrics for sensing humidity enables
the construction of low-power, monolithic CMOS Sensor ICs with low drift and
hysteresis, and excellent long term stability.
Patent Protected. Patents pending
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.
An auxiliary sensor input with power management can be tied directly to an
external thermistor network or other voltage-output sensor. On-board logic
performs calibration/linearization of the external input using user-programmable
coefficients. The least-significant bit of the Si7013's I2C address is programmable,
allowing two devices to share the same bus.
The Si7013 is available in a 3x3 mm DFN package and is reflow solderable. 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 Si7013 offers an accurate, low-power, factory-calibrated digital solution ideal
for measuring humidity, dew-point, and temperature, in applications ranging from
HVAC/R and asset tracking to industrial and consumer platforms.
Rev. 1.1 6/15
Copyright © 2015 by Silicon Laboratories
Si7013-A20
Si7 013- A20
Functional Block Diagram
2
Rev. 1.1
Si7 0 1 3 -A 20
TA B L E O F C O N T E N T S
Section
Page
1. Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2. Typical Application Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
3. Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
4. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
4.1. Relative Humidity Sensor Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
4.2. Hysteresis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
4.3. Prolonged Exposure to High Humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
4.4. PCB Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
4.5. Protecting the Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
4.6. Bake/Hydrate Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
4.7. Long Term Drift/Aging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
2C Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
5. I
5.1. Issuing a Measurement Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
5.2. Reading and Writing User Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
5.3. Measuring Analog Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
5.4. Nonlinear Correction of Voltage Inputs: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
5.5. Firmware Revision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
5.6. Heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
5.7. Electronic Serial Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
6. Control Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
6.1. Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
7. Pin Descriptions: Si7013 (Top View) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
8. Ordering Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
9. Package Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
9.1. Package Outline: 3x3 10-pin DFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
9.2. Package Outline: 3x3 10-pin DFN with Protective Cover . . . . . . . . . . . . . . . . . . . . .40
10. PCB Land Pattern and Solder Mask Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
11. Top Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
11.1. Si7013 Top Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
11.2. Top Marking Explanation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
12. Additional Reference Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
Document Change List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
Rev. 1.1
3
Si7 013- A20
1. Electrical Specifications
Unless otherwise specified, all min/max specifications apply over the recommended operating conditions.
Table 1. Recommended Operating Conditions
Parameter
Symbol
Power Supply
Test Condition
VDD
Min
Typ
Max
Unit
1.9
—
3.6
V
Operating Temperature
TA
I and Y grade
–40
—
+125
°C
Operating Temperature
TA
G grade
–40
—
+85
°C
Table 2. General Specifications
1.9 < VDD < 3.6 V; TA = –40 to 85 °C (G grade) or –40 to 125 °C (I/Y grade); default conversion time unless otherwise noted.
Symbol
Test Condition
Min
Typ
Max
Unit
Input Voltage High
VIH
AD0, SCL, SDA, VSNS pins
0.7xVDD
—
—
V
Input Voltage Low
VIL
AD0, SCL, SDA, VSNS pins
—
—
0.3xVDD
V
Input Voltage Range
VIN
SCL, SDA, VSNS pins with respect to
GND
0.0
—
VDD
V
Input Leakage
IIL
SCL, SDA pins; VIN = GND
—
—
1
μA
Parameter
VSNS pin (200K nominal pull up);
Vin = GND
Output Voltage Low
Output Voltage High
VOL
VOH
IDD
—
—
0.6
V
SDA pin; IOL = 1.2 mA;
VDD = 1.9 V
—
—
0.4
V
—
—
V
VDD– 0.1
—
—
V
VOUT pin, IOH = –1.7 mA, VDD = 3.0 V VDD – 0.4
—
—
V
VOUT pin, IOH = –0.5 mA, VDD = 2.0 V VDD – 0.2
RH conversion in progress
—
150
180
μA
Temperature conversion in progress
—
90
120
μA
Standby, –40 to +85
°C2
—
0.06
0.62
μA
2
—
0.06
3.8
μA
powerup3
—
3.5
4.0
mA
—
3.5
4.0
mA
—
3.1 to 94.2
—
mA
Standby, –40 to +125 °C
Peak IDD during
Peak IDD during I2C operations4
Heater
Current5
μA
SDA pin; IOL = 2.5 mA; VDD = 3.3 V
VOUT pin, IOH = –10 μA
Current
Consumption
5xVDD
IHEAT
Notes:
1. Initiating a RH measurement will also automatically initiate a temperature measurement. The total conversion time will
be tCONV(RH) + tCONV(T).
2. No conversion or I2C transaction in progress. Typical values measured at 25 °C.
3. Occurs once during powerup. Duration is <5 msec.
4. Occurs during I2C commands for Reset, Read/Write User Registers, Read EID, Read Firmware Version, Read/Write
Thermistor Coefficients and Measure Analog Voltage or Thermistor Temperature. Duration is <50 μs for all commands
except Measure Analog Voltage or Thermistor Temperature, which has <150 μs duration when Thermistor Correction is
enabled.
5. Additional current consumption when HTRE bit enabled. See Section “5.6. Heater” for more information.
4
Rev. 1.1
Si7 0 1 3 -A 20
Table 2. General Specifications (Continued)
1.9 < VDD < 3.6 V; TA = –40 to 85 °C (G grade) or –40 to 125 °C (I/Y grade); default conversion time unless otherwise noted.
Parameter
Conversion Time1
Powerup Time
Symbol
Test Condition
Min
Typ
Max
tCONV
12-bit RH
—
10
12
11-bit RH
—
5.8
7
10-bit RH
—
3.7
4.5
8-bit RH
—
2.6
3.1
14-bit temperature
—
7
10.8
13-bit temperature
—
4
6.2
12-bit temperature
—
2.4
3.8
11-bit temperature
—
1.5
2.4
Voltage Normal
—
—
7
Voltage Fast
—
—
3.1
From VDD ≥ 1.9 V to ready for a
conversion, 25 °C
—
18
25
ms
From VDD ≥ 1.9 V to ready for a
conversion, full temperature range
—
—
80
ms
After issuing a software reset
command
—
5
15
ms
tPU
Unit
ms
Notes:
1. Initiating a RH measurement will also automatically initiate a temperature measurement. The total conversion time will
be tCONV(RH) + tCONV(T).
2. No conversion or I2C transaction in progress. Typical values measured at 25 °C.
3. Occurs once during powerup. Duration is <5 msec.
4. Occurs during I2C commands for Reset, Read/Write User Registers, Read EID, Read Firmware Version, Read/Write
Thermistor Coefficients and Measure Analog Voltage or Thermistor Temperature. Duration is <50 μs for all commands
except Measure Analog Voltage or Thermistor Temperature, which has <150 μs duration when Thermistor Correction is
enabled.
5. Additional current consumption when HTRE bit enabled. See Section “5.6. Heater” for more information.
Table 3. I2C Interface Specifications1
1.9 VDD 3.6 V; TA = –40 to +85 °C (G grade) or –40 to +125 °C (I/Y grade) unless otherwise noted.
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
Hysteresis
VHYS
High-to-low versus
low-to-high transition
0.05 x VDD
—
—
V
SCLK Frequency2
fSCL
—
—
400
kHz
SCL High Time
tSKH
0.6
—
—
μs
Notes:
1. All values are referenced to VIL and/or VIH.
2. Depending on the conversion command, the Si7013 may hold the master during the conversion (clock stretch). At
above 300 kHz SCL, the Si7013 may hold the master briefly for user register and device ID transactions. At the highest
I2C speed of 400 kHz the stretching will be <50 μs.
3. Pulses up to and including 50 ns will be suppressed.
Rev. 1.1
5
Si7 013- A20
Table 3. I2C Interface Specifications1 (Continued)
1.9 VDD 3.6 V; TA = –40 to +85 °C (G grade) or –40 to +125 °C (I/Y grade) unless otherwise noted.
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
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
tVD;ACK
From SCL low to data valid
—
—
0.9
μs
50
—
—
ns
SDA Acknowledge Valid Time
Suppressed Pulse
Width3
Between Stop and Start
tSP
Notes:
1. All values are referenced to VIL and/or VIH.
2. Depending on the conversion command, the Si7013 may hold the master during the conversion (clock stretch). At
above 300 kHz SCL, the Si7013 may hold the master briefly for user register and device ID transactions. At the highest
I2C speed of 400 kHz the stretching will be <50 μs.
3. Pulses up to and including 50 ns will be suppressed.
Figure 1. I2C Interface Timing Diagram
6
Rev. 1.1
Si7 0 1 3 -A 20
Table 4. Humidity Sensor
1.9 ≤ VDD ≤ 3.6 V; TA = 30 °C; default conversion time unless otherwise noted.
Parameter
Symbol
1
Operating Range
Accuracy2, 3
Test Condition
Min
Typ
Max
Unit
Non-condensing
0
—
100
%RH
0 – 80% RH
—
±2
±3
%RH
80 – 100% RH
Repeatability-Noise
See Figure 2.
%RH
12-bit resolution
—
0.025
—
%RH RMS
11-bit resolution
—
0.05
—
%RH RMS
10-bit resolution
—
0.1
—
%RH RMS
8-bit resolution
—
0.2
—
%RH RMS
1 m/s airflow, with cover
—
18
—
1 m/s airflow, without cover
—
17
—
Drift vs. Temperature
—
0.05
—
%RH/°C
Hysteresis
—
±1
—
%RH
—
< 0.25
—
%RH/yr
Response Time4
Long Term
τ63%
Stability3
S
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.
Rev. 1.1
7
Si7 013- A20
Figure 2. RH Accuracy at 30 °C
8
Rev. 1.1
Si7 0 1 3 -A 20
Table 5. Temperature Sensor
1.9 ≤ VDD ≤ 3.6 V; TA = –40 to +85 °C (G grade) or –40 to +125 °C (I/Y grade), default conversion time unless otherwise noted.
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
I and Y Grade
–40
—
+125
°C
G Grade
–40
—
+85
°C
–10 °C < tA < 85 °C
—
±0.3
±0.4
°C
Operating Range
Accuracy1
–40 °C < tA < 125 °C
Repeatability-Noise
Response Time2
τ63%
Figure 3.
°C
14-bit resolution
—
0.01
—
°C RMS
13-bit resolution
—
0.02
—
°C RMS
12-bit resolution
—
0.04
—
°C RMS
11-bit resolution
—
0.08
—
°C RMS
Unmounted device
—
0.7
—
s
Si7013-EB board
—
5.1
—
s
—
< 0.01
—
Long Term Stability
°C/Yr
Notes:
1. 14b measurement resolution (default).
2. 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 airflow.
Figure 3. Temperature Accuracy*
*Note: Applies only to I and Y devices beyond +85 °C.
Rev. 1.1
9
Si7 013- A20
Table 6. Voltage Converter Specifications
1.9 ≤ VDD ≤ 3.6 V; TA = –40 to +85 °C (G grade) or –40 to +125 °C (I/Y grade); normal mode conversion time, VREF = 1.25 V
internal or VDDA, buffered and unbuffered mode, unless otherwise noted.
Parameter
Symbol
Test Condition
Resolution
Min
Typ
Max
Unit
—
VREF/
32768
—
V
Integral Non-linearity
INL
|VINP-VINN| < VREF/2
—
1
—
LSB
Differential Non-linearity
DNL
|VINP-VINN| < VREF/2
—
1
—
LSB
N
|VINP-VINN| < VREF/2,
VREF = 1.25 V, Normal Mode
—
25
—
μVRMS
|VINP-VINN| < VREF/2,
VREF = 1.25 V, Fast Mode
—
50
—
Noise
Input Offset
(Buffered Mode)
VOS
|VINP-VINN| = 0
—
—
10
mV
Input Offset
(Unbuffered Mode)1,2
VOS
|VINP-VINN| = 0
—
—
1
mV
Gain Accuracy
∆G
VREF = 1.25 V; gain is absolute
—
+1
+2
%
VREF = VDD; gain is relative to VDD
—
+0.25
+0.5
%
Notes:
1. Guaranteed by design.
2. In unbuffered mode, RIN*CIN should be < 0.5usec. CIN minimum is around 10 pF.
10
Rev. 1.1
Si7 0 1 3 -A 20
Table 7. Thermal Characteristics
Parameter
Symbol
Test Condition
DFN-6
Unit
Junction to Air Thermal Resistance
JA
JEDEC 2-Layer board,
No Airflow
236
°C/W
Junction to Air Thermal Resistance
JA
JEDEC 2-Layer board,
1 m/s Airflow
203
°C/W
Junction to Air Thermal Resistance
JA
JEDEC 2-Layer board,
2.5 m/s Airflow
191
°C/W
Junction to Case Thermal Resistance
JC
JEDEC 2-Layer board
20
°C/W
Junction to Board Thermal Resistance
JB
JEDEC 2-Layer board
112
°C/W
Table 8. Absolute Maximum Ratings1,2
Parameter
Min
Typ
Max
Unit
Ambient temperature
under bias
–55
—
125
°C
Storage Temperature
–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” for
details.
Rev. 1.1
11
Si7 013- A20
2. Typical Application Circuits
The primary function of the Si7013 is to measure relative humidity and temperature. Figure 4 demonstrates the
typical application circuit to achieve these functions; pins 6 and 7 are not required and should be left unconnected.
WR9
)
N
9''' 9''$
6&/
6L
N
6'$
9616
$'9287
6&/
6'$
9,13
9,11
*1'' *1'$
Figure 4. Typical Application Circuit for Relative Humidity and Temperature Measurement
The application circuit shown in Figure 5 uses the auxiliary analog pins for measuring a remote temperature using
a thermistor.
Figure 5. Typical Application Circuit for Thermistor Interface with AD0 = 1
The voltage connected at VDDA serves as the reference voltage for both the Analog-to-Digital converter and the
resistor string. Therefore, the ADC must be configured to take its reference from VDDA. The top of the resistor
string is connected to the VOUT pin, allowing the resistor string to be powered down, saving power between
temperature conversions. In this mode of operation, the analog inputs are buffered and present an input
impedance of > 100 k
12
Rev. 1.1
Si7 0 1 3 -A 20
The AD0/VOUT pin is a dual function pin. At powerup, it functions as an address select pin and selects the least
significant I2C Figure 5, the AD0/VOUT pin is pulled high, selecting AD0 = 1. In Figure 6, the AD0/VOUT pin is
pulled low selecting AD0 = 0.
Figure 6. Typical Application Circuit for Thermistor Interface with AD0 = 0
WR9
&
)
9WR9
9ROWDJH,QSXW
5
N
9,13
9,11
5
N
9''$ 9'''
6&/
6&/
6'$
6'$
9616
5
N
5
N
6L
$'9287
*1'' *1'$
Figure 7. Typical Application Circuit for Single Ended 0 to 3 V Measurement
Figure 7 demonstrates a single ended 0 to 3 V input range configuration. The voltage reference is the internal
1.25 V reference. The 1 k and 2 k resistor divider keeps the voltage range to 1.0 V, which is within the
recommended 80% of VREF. Full scale of 32767 counts is 3.75 V.
Rev. 1.1
13
Si7 013- A20
3. Bill of Materials
Table 9. Typical Application Circuit BOM for Relative Humidity and Temperature Measurement
Reference
Description
Mfr Part Number
Manufacturer
R1
Resistor, 10 k, ±5%, 1/16W, 0603
CR0603-16W-103JT
Venkel
R2
Resistor, 10 k, ±5%, 1/16W, 0603
CR0603-16W-103JT
Venkel
C1
Capacitor, 0.1 μF, 16 V, X7R, 0603
C0603X7R160-104M
Venkel
U1
IC, Digital Temperature/humidity Sensor
Si7013-A20
Silicon Labs
Table 10. Typical Application Circuit BOM for Thermistor Interface
Reference
Description
Mfr Part Number
Manufacturer
R1
Resistor, 10 k, ±5%, 1/16W, 0603
CR0603-16W-103JT
Venkel
R2
Resistor, 10 k, ±5%, 1/16W, 0603
CR0603-16W-103JT
Venkel
R3
Resistor, 24 k, ±1%, 1/16W, 0603
CR0603-16W-2402F
Venkel
R4
Resistor, 24 k, ±1%, 1/16W, 0603
CR0603-16W-2402F
Venkel
C1
Capacitor, 0.1 μF, 16 V, X7R, 0603
C0603X7R160-104M
Venkel
C2
Capacitor, 0.1 μF, 16 V, X7R, 0603
C0603X7R160-104M
Venkel
TH1
Thermistor, 10 k
NTCLE100E3103
Vishay
U1
IC, digital temperature/humidity sensor
Si7013-A20
Silicon Labs
Table 11. Typical Application Circuit BOM for Single Ended 0 to 3 V Measurement
14
Reference
Description
Mfr Part Number
Manufacturer
R1
Resistor, 10 k, ±5%, 1/16W, 0603
CR0603-16W-103JT
Venkel
R2
Resistor, 10 k, ±5%, 1/16W, 0603
CR0603-16W-103JT
Venkel
R3
Resistor, 2 k, ±1%, 1/16W, 0603
CR0603-16W-2001F
Venkel
R4
Resistor, 1 k, ±1%, 1/16W, 0603
CR0603-16W-1001F
Venkel
C1
Capacitor, 0.1 μF, 16 V, X7R, 0603
C0603X7R160-104M
Venkel
U1
IC, Digital Temperature/humidity Sensor
Si7013-A20
Silicon Labs
Rev. 1.1
Si7 0 1 3 -A 20
4. Functional Description
Figure 8. Si7013 Block Diagram
The Si7013 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 an
I2C interface all in a single chip. The Si7013 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 Si7013 to achieve excellent long term stability and immunity to
contaminants with low drift and hysteresis. The Si7013 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.
The auxiliary sensor input option exists to use the ADC with external inputs and reference. Suitable buffers are
included to allow the part to be connected to high impedance circuitry such as bridges or other types of sensors,
without introducing errors.
While the Si7013 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 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 effect on
sensor accuracy.
The effects of humidity sensor “memory”.
Each of these items is discussed in more detail in the following sections.
Rev. 1.1
15
Si7 013- 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 9 shows the result
of a typical sweep.
Figure 9. Measuring Sensor Accuracy Including Hysteresis
The RH accuracy is defined as the dotted line shown in Figure 9, 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 Si7013 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
Accuracy
The accuracy specification does not include:
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
Effects
16
Rev. 1.1
Si7 0 1 3 -A 20
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 9. 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 9, 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 affect by baking the device (see Section “4.6. Bake/Hydrate Procedure” ).
4.4. PCB Assembly
4.4.1. Soldering
Like most ICs, Si7013 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. The following guidelines
should be observed during PCB assembly:
Si7013
devices are compatible with standard board assembly processes. Devices should be soldered
using reflow per the recommended card reflow profile. See Section “10. 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 application note “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 KaptonKPPD-1/8 can be installed during PCB
assembly.
Si7013s 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 “8. Ordering Guide” for a list of ordering part numbers that
include the cover.
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 Si7013 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.
Rev. 1.1
17
Si7 013- A20
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 10. Si70xx with Factory-Installed Protective Cover
18
Rev. 1.1
Si7 0 1 3 -A 20
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 Si7013 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 “8. 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
“9. Package Outline” . Other characteristics of the cover are listed in Table 12.
Table 12. 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
Rev. 1.1
19
Si7 013- A20
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:
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.
4.7. 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 Si7013 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.
20
Rev. 1.1
Si7 0 1 3 -A 20
5. I2C Interface
The Si7013 communicates with the host controller over a digital I2C interface. The 7-bit base slave address is 0x40
or 0x41; the least significant bit is pin programmable.
Table 13. I2C Slave Address Byte
A6
A5
A4
A3
A2
A1
A0
R/W
1
0
0
0
0
0
AD0
1/0
Master I2C devices communicate with the Si7013 using a command structure. The commands are listed in the I2C
command table. Commands other than those documented below are undefined and should not be sent to the
device.
Table 14. I2C Command Table
Command Description
Command Code
Measure Relative Humidity, Hold Master Mode
0xE5
Measure Relative Humidity, No Hold Master Mode
0xF5
Measure Temperature, Hold Master Mode
0xE3
Measure Temperature, No Hold Master Mode
0xF3
Measure Analog Voltage or Thermistor Temperature
0xEE
Read Temperature Value from Previous RH Measurement
0xE0
Reset
0xFE
Write Voltage Measurement Setup (User register 2)
0x50
Read Voltage Measurement Setup (User register 2)
0x10
Write RH/T Measurement Setup (User register 1)
0xE6
Read RH/T Measurement Setup (User register 1)
0xE7
Write Heater Setup (User register 3)
0x51
Read Heater Setup (User register 3)
0x11
Write Thermistor Correction Coefficient
0xC5
Read Thermistor Correction Coefficient
0x84
Read Electronic ID 1st Word
0xFA 0x0F
Read Electronic ID 2nd Word
0xFC 0xC9
Read Firmware Revision
0x84 0xB8
Rev. 1.1
21
Si7 013- A20
5.1. Issuing a Measurement Command
The measurement commands instruct the Si7013 to perform one of four possible measurements; Relative
Humidity, Temperature, Auxiliary Temperature, or Analog Voltage. While the measurement is in progress, the
option of either clock stretching (Hold Master Mode) or Not Acknowledging read requests (No Hold Master Mode)
is available to indicate to the master that the measurement is in progress. For Humidity and Temperature
measurements, the chosen command code determines which mode is used. For Auxiliary Temperature and
Analog Voltage measurements, No Hold Master mode can be enabled by writing a "1" to bit D6 in register 2. Note
that internal Humidity and Temperature measurements should not be made with this bit set.
Optionally, a checksum byte can be returned from the slave for use in checking for transmission errors for Relative
Humidity and Temperature measurements. The checksum byte is optional after initiating an RH or temperature
measurement with commands 0xE5, 0xF5, 0xE3 and 0xF3. The checksum byte is required for reading the
electronic ID with commands 0xFA 0x0F and 0xFC 0xC9. For all other commands, the checksum byte is not
supported. The checksum byte will follow the least significant measurement byte if it is acknowledged by the
master. The checksum byte is not returned if the master “not acknowledges” the least significant measurement
byte. The checksum byte is calculated using a CRC generator polynomial of x8 + x5 + x4 + 1 with an initialization of
0x00.
Table 15. I2C Bit Descriptions
Name
Symbol
Description
START
S
SDA goes low while SCL high.
STOP
P
SDA goes high while SCL high.
Repeated START
Sr
SDA goes low while SCL high. It is allowable to generate a STOP before the
repeated start. SDA can transition to high before or after SCL goes high in
preparation for generating the START.
READ
R
Read bit = 1
WRITE
W
Write bit = 0
All other bits
—
SDA value must remain high or low during the entire time SCL is high (this is
the set up and hold time in Figure 1).
In the I2C sequence diagrams in the following sections, bits produced by the master and slave are color coded as
shown:
Master
22
Slave
Rev. 1.1
Si7 0 1 3 -A 20
*Note: Device will NACK the slave address byte until conversion is complete.
Rev. 1.1
23
Si7 013- A20
5.1.1. Measuring Relative Humidity
Once a relative humidity measurement has been made, the results of the measurement may be converted to
percent relative humidity by using the following expression:
125 RH_Code
%RH = --------------------------------------- – 6
65536
Where:
%RH is the measured relative humidity value in %RH
RH Code is the 16-bit word returned by the Si7013
A humidity measurement will always return XXXXXX10 in the LSB field.
Note: 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, and it is
acceptable to limit the range of RH results to 0 to 100%RH in the host software by truncating values that are slightly outside of this range.
5.1.2. Measuring Temperature
Each time a relative humidity measurement is made a temperature measurement is also made for the purposes of
temperature compensation of the relative humidity measurement. If the temperature value is required, it can be
read using command 0xE0; this avoids having to perform a second temperature measurement. The measure
temperature commands 0xE3 and 0xF3 will perform a temperature measurement and return the measurement
value, command 0xE0 does not perform a measurement but returns the temperature value measured during the
relative humidity measurement. The checksum output is not available with the 0xE0 command.
The results of the temperature measurement may be converted to temperature in degrees Celsius (°C) using the
following expression:
175.72 Temp_Code
Temperature (C = -------------------------------------------------------- – 46.85
65536
Where:
Temperature (°C) is the measured temperature value in °C
Temp_Code is the 16-bit word returned by the Si7013
A temperature measurement will always return XXXXXX00 in the LSB field.
24
Rev. 1.1
Si7 0 1 3 -A 20
5.2. Reading and Writing User Registers
There are three user registers on the Si7013 that allow the user to set the configuration of the Si7013, the
procedure for accessing these registers is set out below. The checksum byte is not supported after reading a user
register.
Sequence to read a register
Slave
S
Address
W
Slave
Read Reg
A
A
Cmd
Sr
Addres
R
A
s
Read
Data
NA
P
Sequence to write a register
S
Slave
Address
W
Write Reg
A
Cmd
A
Write Data
A
P
5.3. Measuring Analog Voltage
The analog voltage input pins can accept voltage inputs within the ranges shown in Table 16. VREFP is internally
connected to VDDA or to an internal 1.25 V reference voltage.
Table 16. Analog Input Ranges
VINP Input Range
Buffered Input
Unbuffered Input
VINN Input Range
Min
Max
Min
Max
0.35 V
VDD–0.35 V
0.35 V
VDD–0.35 V
0V
VDD
0V
VDD
The voltage conversion output is a signed 16-bit integer that will vary from –32768 to 32767 as the input (VINP–
VINN) goes from –V to +V. For best performance, it is recommended that |VINP–VINN| be limited to Vref/2. With
minor degradation in performance, this can be extended to 0.8*Vref. The checksum option for voltage mode
conversions is not supported.
Rev. 1.1
25
Si7 013- A20
5.4. Nonlinear Correction of Voltage Inputs:
The Si7013 contains a look-up table for applying non-linear correction to external voltage measurements. The
look-up table is contained in an internal, user-programmable OTP memory. The OTP memory is non-volatile,
meaning the values are retained even when the device is powered off.
Once the lookup table values have been programmed, this correction is invoked by writing a “1” to bit 5 of user
register 2. Note that humidity measurements should not be performed when this bit is set.
5.4.1. Calculating Lookup Table Values
The non-linear correction is based on 10 points. Each point consists of the ideal output for a given expected A/D
measurement result.
Values between the ideal output points are interpolated based on the slope between the two output points.
The lookup table is stored in the Si7013 memory. Values must be programmed for each pair of input values and
ideal output points. In addition, the slope between each ideal output point must also be programmed (the Si7013
will not automatically calculate the slope). Only 9 of the input/output pairs need to be in the table because the 10th
output value is determined by the slope equation.
The table contains 3 sets of 9 values:
In(1-9):
16-bit signed values for each input point read from the ADC. See Section “5.3. Measuring Analog
Voltage” for more information on setting up the ADC measurement.
Out(1-9): 16-bit unsigned values for each ideal output point that should be used for each input point.
Slope(1-9): 16-bit signed values for the slope between each ideal output point.
Note: The table must be arranged in order of decreasing input values.
The slope values must be calculated as follows:
slopeN =256*(outputN+1 – outputN)/(inputN+1 – inputN)
The actual output value is determined by extrapolation:
If in >in2, out = out1+slope1*(in-in1)/256
Else if in >in3, out = out2+slope2*(in-in2)/256
Else if in >in4, out = out3+slope3*(in-in3)/256
Else if in >in5, out = out4+slope4*(in-in4)/256
Else if in >in6, out = out5+slope5*(in-in5)/256
Else if in >in7, out = out6+slope6*(in-in6)/256
Else if in >in8, out = out7+slope7*(in-in7)/256
Else if in >in9, out = out8+slope8*(in-in8)/256
Else out = out9+slope9*(in-in9)
26
Rev. 1.1
Si7 0 1 3 -A 20
5.4.2. Entering Lookup Table Values into OTP Memory:
The table is entered into memory addresses 0x82 – 0xB7 one byte at a time. Until the OTP has been programmed,
all memory addresses default to a value of 0xFF. The table below indicates where the values are written:
Table 17. Lookup Table Memory Map
Name
Memory
Location
Name
Memory
Location
Name
Memory
Location
Input1 (MSB)
0x82
Output1 (MSB)
0x94
Slope1 (MSB)
0xA6
Input1 (LSB)
0x83
Output1 (LSB)
0x95
Slope1 (LSB)
0xA7
Input2 (MSB)
0x84
Output2 (MSB)
0x96
Slope2 (MSB)
0xA8
Input2 (LSB)
0x85
Output2 (LSB)
0x97
Slope2 (LSB)
0xA9
Input3 (MSB)
0x86
Output3 (MSB)
0x98
Slope3 (MSB)
0xAA
Input3 (LSB)
0x87
Output3 (LSB)
0x99
Slope3 (LSB)
0xAB
Input4 (MSB)
0x88
Output4 (MSB)
0x9A
Slope4 (MSB)
0xAC
Input4 (LSB)
0x89
Output4 (LSB)
0x9B
Slope4 (LSB)
0xAD
Input5 (MSB)
0x8A
Output5 (MSB)
0x9C
Slope5 (MSB)
0xAE
Input5 (LSB)
0x8B
Output5 (LSB)
0x9D
Slope5 (LSB)
0xAF
Input6 (MSB)
0x8C
Output6 (MSB)
0x9E
Slope6 (MSB)
0xB0
Input6 (LSB)
0x8D
Output6 (LSB)
0x9F
Slope6 (LSB)
0xB1
Input7 (MSB)
0x8E
Output7 (MSB)
0xA0
Slope7 (MSB)
0xB2
Input7 (LSB)
0x8F
Output7 (LSB)
0xA1
Slope7 (LSB)
0xB3
Input8 (MSB)
0x90
Output8 (MSB)
0xA2
Slope8 (MSB)
0xB4
Input8 (LSB)
0x91
Output8 (LSB)
0xA3
Slope8 (LSB)
0xB5
Input9 (MSB)
0x92
Output9 (MSB)
0xA4
Slope9 (MSB)
0xB6
Input9 (LSB)
0x93
Output9 (LSB)
0xA5
Slope9 (LSB)
0xB7
Rev. 1.1
27
Si7 013- A20
The sequences for reading and writing thermistor coefficients are given below:
For example, to program a Si7013 at slave address 0x40 with the 16-bit value 0x4C2F, starting at memory location
0x82, you would write:
<Start Condition> 0x40 W ACK 0xC5 ACK 0x82 ACK 0x4C ACK <Stop Condition>
<Start Condition> 0x40 W ACK 0xC5 ACK 0x83 ACK 0x2F ACK <Stop Condition>
The internal memory is one-time-programmable, so it is not possible to change the values once written. However,
to verify the values were written properly use command 0x84. For example, to verify that 0x4C was written to
location 0x82 use:
<Start Condition> 0x40 W ACK 0x84 ACK 0x82 ACK <Start Condition> 0x40 R ACK 0x4C NACK <Stop
Condition> where 0x4C is the expected return value of the read transaction.
28
Rev. 1.1
Si7 0 1 3 -A 20
5.4.3. Example Thermistor Calculations
For the Si7013 evaluation board with a 10 K ohm thermistor and two 24.3 Kbias resistors and assuming the A/D
conversion is done using VDD as a reference with buffered inputs, the ideal input voltage versus temperature is:
Vin = VDD *Rthemistor/(Rthermisor+46.4 K)
Since VDD is also the reference then the expected A/D conversion result is:
A/D counts = 32768* Rthemistor/(Rthermisor+46.4 K)
If it is desired to linearize this result for the same temperature representation as the on board temperature sensor:
Temperature °C = (Output_Code*175.72/65536 – 46.85), then the desired output code is:
Output_Code = 65536*(Temperature+46.85)/175.72
Using thermistor data sheet values of resistance versus temperature and choosing to linearize at the points –15C,
–5C, 5C, 15C, 25C, 35C, 45C, 55C, 65C and 75C results in the following. The values in gray are the table entries
for Si7013:
Table 18. Example Non-Linear Correction to Thermistor Voltage Measurements
Temperature
(Degrees C)
Thermistor
Resistance
Vin/VDD
A/D
Codes
Desired
Code
Slope
Table Entry
–15
71746
0.596164
19535
11879
–218
1
–5
41813
0.462467
15154
15608
–241
2
5
25194
0.34141
11187
19338
–298
3
15
15651
0.243592
7982
23067
–400
4
25
10000
0.170648
5592
26797
–563
5
35
6556
0.118863
3895
30527
–813
6
45
4401
0.83036
2721
34256
–1186
7
55
3019
0.058486
1916
37986
–1739
8
65
2115
0.041704
1367
41715
–2513
9
75
1509
0.030114
75
45445
Rev. 1.1
29
Si7 013- A20
Once the table entry values are calculated, they should be programmed to the Si7013 memory locations as shown
below:
Table 19. Example Non-Linear Thermistor Correction Entries into Si7013 Memory
Memory
Location
A/D
Codes
Value
Memory
Location
Desired
Codes
Value
Memory
Location
Slope
Value
82
19535
4C
94
11879
2E
A6
–218
FF
4F
95
67
A7
3B
96
3C
A8
32
97
F8
A9
2B
98
4B
AA
B3
99
8A
AB
1F
9A
5A
AC
2E
9B
1B
AD
15
9C
68
AE
D8
9D
Ad
AF
F
9E
77
B0
37
9F
3F
B1
A
A0
85
B2
A1
A1
D0
B3
7
A2
94
B4
7C
A3
62
B5
5
A4
A2
B6
57
A5
F3
B7
83
84
15154
85
86
11187
87
88
7982
89
8A
5592
8B
8C
3895
8D
8E
2721
8F
90
1916
91
92
93
30
1367
15608
19338
23067
26797
30527
34256
37986
41715
Rev. 1.1
26
–241
FF
0F
–298
FE
D6
–400
FE
70
–563
FD
CD
–813
FC
D3
–1186
FB
5E
–1739
F9
35
–2513
F6
2F
Si7 0 1 3 -A 20
5.5. Firmware Revision
The internal firmware revision can be read with the following I2C transaction:
S
Slave
Address
W
A
R
0x84
A
A
FWREV
0xB8
A
NA
A
S
Slave
Address
P
The values in this field are encoded as follows:
0xFF = Firmware revision 1.0
0x20 = Firmware revision 2.0
5.6. Heater
The Si7013 contains an integrated resistive heating element that may be used to raise the temperature of the
sensor. This element can be used to test the sensor, to drive off condensation, or to implement dew-point
measurement when the Si7013 is used in conjunction with a separate temperature sensor such as another Si7013
(the heater will raise the temperature of the internal temperature sensor).
The heater can be activated using HTRE, bit 2 in User Register 1. Turning on the heater will reduce the tendency
of the humidity sensor to accumulate an offset due to "memory" of sustained high humidity conditions. Several
different power levels are available. The various settings are adjusted using User Register 3 and are described in
Table 20.
Table 20. Heater Control Settings
HEATER[3:0] Typical Current
Draw* (mA)
0000
3.09
0001
9.18
0010
15.24
...
...
0100
27.39
...
...
1000
51.69
...
...
1111
94.20
*Note: Assumes VDD = 3.3 V.
Rev. 1.1
31
Si7 013- A20
5.7. Electronic Serial Number
The Si7013 provides a serial number individualized for each device that can be read via the I2C serial interface.
Two I2C commands are required to access the device memory and retrieve the complete serial number. The
command sequence, and format of the serial number response is described in the figure below:
First access:
S
Slave Address
W
ACK
0xFA
ACK
0X0F
ACK
S
Slave Address
R
ACK
SNA_3
ACK
CRC
ACK
SNA_2
ACK
CRC
ACK
SNA_1
ACK
CRC
ACK
SNA_0
ACK
CRC
NACK
S
Slave Address
W
ACK
0xFC
ACK
0xC9
ACK
S
Slave Address
R
ACK
SNB_3
ACK
SNB_2
ACK
CRC
ACK
SNB_1
ACK
SNB_0
ACK
CRC
NACK
P
2nd access:
P
The format of the complete serial number is 64-bits in length, divided into 8 data bytes. The complete serial number
sequence is shown below:
SNA_3
SNA_2
SNA_1
SNA_0
SNB_3
SNB_2
SNB_1
SNB_0
The SNB3 field contains the device identification to distinguish between the different Silicon Labs relative humidity
and temperature devices. The value of this field maps to the following devices according to this table:
0x00 or 0xFF engineering samples
0x0D=13=Si7013
0x14=20=Si7020
0x15=21=Si7021
32
Rev. 1.1
Si7 0 1 3 -A 20
6. Control Registers
Table 21. Register Summary
Register
Bit 7
Bit 6
User Register 1
RES1
VDDS
User Register 2
User Register 3
NO_HOLD
Bit 5
Bit 4
Bit 3
RSVD
THERM
_CORR
CONV_
TIME
RSVD
RSVD
Bit 2
Bit 1
Bit 0
HTRE
RSVD
RES0
VIN_BUF
VREFP
VOUT
HEATER[3:0]
Notes:
1. Any register not listed here is reserved and must not be written.The result of a read operation on these registers is
undefined.
2. Except where noted, reserved register bits always read back as "1", and are not affected by write operations. For future
compatibility, it is recommended that prior to a write operation, registers should be read. Then the values read from the
RSVD bits should be written back unchanged during the write operation.
Rev. 1.1
33
Si7 013- A20
6.1. Register Descriptions
Register 1. User Register 1
Bit
D7
D6
Name
RES1
VDDS
Type
R/W
R
D5
D4
D3
D2
D1
D0
RSVD
HTRE
RSVD
RES0
R/W
R/W
R/W
R/W
Reset Settings = 0011_1010
Bit
Name
D7; D0
RES[1:0]
D6
VDDS
Function
Measurement Resolution:
RH
00:
12 bit
01:
8 bit
10:
10 bit
11:
11 bit
VDD Status:
0:
1:
Temp
14 bit
12 bit
13 bit
11 bit
VDD OK
VDD Low
The minimum recommended operating voltage is 1.9 V. A transition of the VDD status bit from 0 to 1 indicates that VDD is
between 1.8 V and 1.9 V. If the VDD drops below 1.8 V, the
device will no longer operate correctly.
34
D5, D4, D3
RSVD
Reserved
D2
HTRE
1 = On-chip Heater Enable
0 = On-chip Heater Disable
D1
RSVD
Reserved
Rev. 1.1
Si7 0 1 3 -A 20
Register 2. User Register 2
Bit
D7
D6
D5
D4
D3
D2
D1
D0
Name
RSVD
NO_HOLD
THERM
_CORR
CONV_
TIME
RSVD
VIN_BUF
VREFP
VOUT
Type
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Reset Settings = 0000_100x
Bit
Name
Function
D7
RSVD
D6
NO_HOLD
1: Auxiliary voltage and thermistor measurements made in No Hold
Master Mode. Note that this bit must be set to "0" before initiating an
internal temperature or humidity measurement.
0: Auxiliary voltage and thermistor measurements made in Hold Master
Mode.
D5
THERM_CORR
1: Thermistor correction enabled for auxiliary voltage and thermistor
measurements. Note that this bit must be set to "0" before initiating an
internal temperature or humidity measurement.
0: Thermistor correction disabled.
D4
CONV_TIME
D3
RSVD
D2
VIN_BUF
0: VINN and VINP inputs are unbuffered
1: VINN and VINP inputs are buffered
D1
VREFP
0: A/D reference source is internal 1.25V
1: A/D reference source is VDDA
D0
VOUT*
0: VOUT pin is set to GNDD
1: VOUT pin is set to VDDD
Reserved
Conversion Time. Selects conversion time and noise floor of the
voltage ADC.
0: Normal mode
1: Fast mode
Reserved
Note: Default is powerup state of VOUT pin
*Note: VOUT is generally used for driving an external thermistor interface. Default setting is the same as the power up
setting.
Rev. 1.1
35
Si7 013- A20
Register 3. User Register 3
Bit
D7
D6
D5
D4
D3
D2
Name
RSVD
Heater [3:0]
Type
R/W
R/W
Reset Settings = 0000_0000
Bit
D3:D0
Name
HEATER[3:0]
Function
Heater Current
D3
D2
D1
D0
0
0
0
0
3.09 mA
0
0
0
1
9.18 mA
0
0
1
0
15.24 mA
0
27.39 mA
0
51.69 mA
1
94.20 mA
...
0
1
0
...
1
0
0
...
1
D7,D6,
D5,D4
36
D1
RSVD
1
1
Reserved
Rev. 1.1
D0
Si7 0 1 3 -A 20
7. Pin Descriptions: Si7013 (Top View)
Pin Name
Pin #
Pin Description
SDA
1
I2C data.
AD0/VOUT
2
Dual function pin.
This pin can be switched high or low and is generally used to drive an external
thermistor interface.
On powerup, this pin acts as a device address select pin. Tie high or low to set device
address LSB.
See Figure 5 and Figure 6.
GNDD
3
Digital ground. This pin is connected to ground on the circuit board.
GNDA
4
Analog ground. This pin is connected to ground on the circuit board.
VSNS
5
Voltage Sense Input. Tie to VDD.*
VINP
6
Analog to digital converter positive input.
VINN
7
Analog to digital converter negative input.
VDDA
8
Analog power. This pin is connected to power on the circuit board.
VDDD
9
Digital power. This pin is connected to power on the circuit board.
SCL
10
I2C clock
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.
*Note: VSNS must be high at power up or device will be held in reset.
Rev. 1.1
37
Si7 013- A20
8. Ordering Guide
Table 22. Device Ordering Guide
P/N
Description
Max. Accuracy
Temp
RH
Pkg
Operating
Range (°C)
Protective
Cover
Packing
Format
Si7013-A20-GM
Digital temperature/ humidity sensor
±0.4 °C
± 3%
DFN 6
–40 to +85 °C
N
Tube
Si7013-A20-GMR
Digital temperature/ humidity sensor
±0.4 °C
± 3%
DFN 6
–40 to +85 °C
N
Tape
& Reel
Si7013-A20-GM1
Digital temperature/ humidity sensor
±0.4 °C
± 3%
DFN 6
–40 to +85 °C
Y
Cut Tape
Si7013-A20-GM1R
Digital temperature/ humidity sensor
±0.4 °C
± 3%
DFN 6
–40 to +85 °C
Y
Tape &
Reel
Si7013-A20-IM
Digital temperature/ humidity sensor—
industrial temp range
±0.4 °C
± 3%
DFN 6
–40 to +125 °C
N
Tube
Si7013-A20-IMR
Digital temperature/ humidity sensor—
industrial temp range
±0.4 °C
± 3%
DFN 6
–40 to +125 °C
N
Tape &
Reel
Si7013-A20-IM1
Digital temperature/ humidity sensor—
industrial temp range
±0.4 °C
± 3%
DFN 6
–40 to +125 °C
Y
Cut Tape
Si7013-A20-IM1R
Digital temperature/ humidity sensor—
industrial temp range
±0.4 °C
± 3%
DFN 6
–40 to +125 °C
Y
Tape &
Reel
Si7013-A20-YM0
Digital temperature/ humidity sensor—
automotive
±0.4 °C
± 3%
DFN 6
–40 to +125 °C
N
Tube
Si7013-A20-YM0R
Digital temperature/ humidity sensor—
automotive
±0.4 °C
± 3%
DFN 6
–40 to +125 °C
N
Tape &
Reel
Si7013-A20-YM1
Digital temperature/ humidity sensor—
automotive
±0.4 °C
± 3%
DFN 6
–40 to +125 °C
Y
Cut Tape
Si7013-A20-YM1R
Digital temperature/ humidity sensor—
automotive
±0.4 °C
± 3%
DFN 6
–40 to +125 °C
Y
Tape
& Reel
Note: The "A" denotes product revision A and "20" denotes firmware revision 2.0.
38
Rev. 1.1
Si7 0 1 3 -A 20
9. Package Outline
9.1. Package Outline: 3x3 10-pin DFN
Figure 11 illustrates the package details for the Si7013. Table 22 lists the values for the dimensions shown in the
illustration.
Figure 11. 10-pin DFN Package Drawing
Table 23. 10-Pin DFN Package Dimensions
Dimension
Min
Nom
Max
Dimension
Min
Nom
Max
A
0.70
0.75
0.80
H2
1.39
1.44
1.49
A1
0.00
0.02
0.05
L
0.50
0.55
0.60
b
0.18
0.25
0.30
aaa
0.10
bbb
0.10
ccc
0.05
D
D2
3.00 BSC.
1.20
1.30
1.40
e
0.50 BSC.
ddd
0.10
E
3.00 BSC.
eee
0.05
fff
0.05
E2
2.40
2.50
2.60
H1
0.85
0.90
0.95
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.
Rev. 1.1
39
Si7 013- A20
9.2. Package Outline: 3x3 10-pin DFN with Protective Cover
Figure 12 illustrates the package details for the Si7013 with the optional protective cover. Table 23 lists the values
for the dimensions shown in the illustration.
Figure 12. 10-pin DFN with Protective Cover
Table 24. 10-pin DFN with Protective Cover Diagram Dimensions
Dimension
Min
Nom
Max
Dimension
Min
Nom
Max
A
—
—
1.21
F1
2.70
2.80
2.90
A1
0.00
0.02
0.05
F2
2.70
2.80
2.90
A2
0.70
0.75
0.80
h
0.76
0.83
0.90
b
0.18
0.25
0.30
L
0.50
0.55
0.60
R1
0.45
0.50
0.55
D
D2
3.00 BSC.
1.20
1.30
1.40
0.10
e
0.50 BSC.
bbb
0.10
E
3.00 BSC.
ccc
0.05
ddd
0.10
eee
0.05
E2
2.40
2.50
2.60
Notes:
1. All dimensions shown are in millimeters (mm).
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
40
aaa
Rev. 1.1
Si7 0 1 3 -A 20
10. PCB Land Pattern and Solder Mask Design
Table 25. PCB Land Pattern Dimensions
Symbol
mm
C1
2.80
E
0.50
P1
1.40
P2
2.60
X1
0.30
Y1
1.00
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 0.95 mm square openings on 1.25 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. 1.1
41
Si7 013- A20
11. Top Marking
11.1. Si7013 Top Marking
11.2. Top Marking Explanation
42
Mark Method:
Laser
Pin 1 Indicator:
Circle = 0.30 mm Diameter
Upper-Left Corner
Font Size:
0.30 mm
Line 1 Marking:
TTTT = Mfg Code
Rev. 1.1
Si7 0 1 3 -A 20
12. Additional Reference Resources
AN607:
Si70xx Humidity Sensor Designer’s Guide
Rev. 1.1
43
Si7 013- A20
DOCUMENT CHANGE LIST
Revision 0.9 to Revision 0.91
Updated Table 2 on page 4.
Revision 0.91 to Revision 1.0
Updated document revision to 1.0.
Revision 1.0 to Revision 1.1
Updated Footnote 2 in Table 3 on page 5
Updated Section “4.5. Protecting the Sensor”
Updated Table 12 on page 19
Corrected a typo in the I2C sequence for no-hold
mode in Section “5. I2C Interface”
Corrected a typo in Table 15 on page 22
Updated Table 24 on page 40 dimensions F1 and F2
44
Rev. 1.1
Si7 0 1 3 -A 20
CONTACT INFORMATION
Silicon Laboratories Inc.
400 West Cesar Chavez
Austin, TX 78701
Tel: 1+(512) 416-8500
Fax: 1+(512) 416-9669
Toll Free: 1+(877) 444-3032
Please visit the Silicon Labs Technical Support web page:
https://www.silabs.com/support/pages/contacttechnicalsupport.aspx
and register to submit a technical support request.
Patent Notice
Silicon Labs invests in research and development to help our customers differentiate in the market with innovative low-power, small size, analogintensive mixed-signal solutions. Silicon Labs' extensive patent portfolio is a testament to our unique approach and world-class engineering team.
The information in this document is believed to be accurate in all respects at the time of publication but is subject to change without notice.
Silicon Laboratories assumes no responsibility for errors and omissions, and disclaims responsibility for any consequences resulting from
the use of information included herein. Additionally, Silicon Laboratories assumes no responsibility for the functioning of undescribed features or parameters. Silicon Laboratories reserves the right to make changes without further notice. Silicon Laboratories makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Silicon Laboratories assume any
liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation
consequential or incidental damages. Silicon Laboratories products are not designed, intended, or authorized for use in applications intended to support or sustain life, or for any other application in which the failure of the Silicon Laboratories product could create a situation where
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Rev. 1.1
45