SI7020-A20 Datasheet, PDF (25/36 Pages) Silicon Laboratories – IC HUMIDITY AND TEMPERATURE SENSOR

0x00 or 0xFF engineering samples
0x0D=13=Si7013
0x14=20=Si7020
0x15=21=Si7021
5.4. Firmware Revision
The internal firmware revision can be read with the following I²C transaction:
Slave
S
W
A
0x84
A
Address
0xB8
Si7020-A20
Slave
A
S
Address
RA
FWREV
A NA P
The values in this field are encoded as follows:
0xFF = Firmware version 1.0
0x20 = Firmware version 2.0
5.5. Heater
The Si7020 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 Si7020 is used in conjunction with a separate temperature sensor such as another Si7020
(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 the Heater Control Register and are
described in the following table.
Table 13. 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
25