Datasheet

Bosch Sensortec | BME680 Datasheet
8 | 50
Modifications reserved |Data subject not change without notice | Printed in Germany
Document number: BST-BME680-DS001-00 Revision_1.0_072017
1.2 Gas sensor specification
Table 2 lists the gas sensor specification. All the parameters are deduced from lab measurements under controlled
environmental conditions, which are compliant to the ISO16000-29 standard “Test methods for VOC detectors”. Detailed
procedure to measure the gas sensor is available in the Application Note: Measurement Instructions for Lab Environment.
Referring to Chapter 4, a software solution (BSEC: Bosch Software Environmental Cluster) is available for the BME680. The
software is carefully engineered to seamlessly work with the 4-in-1 integrated sensors inside the BME680. Based on an
intelligent algorithm, the BSEC provides an indoor air quality (IAQ) output. In principle, this output is in an index that can have
values between 0 and 500 with a resolution of 1 to indicate or quantify the quality of the air available in the surrounding. Table
4 lists the IAQ system specification. The detailed classification and color coding of the IAQ index is described in Table 4.
Furthermore, the BSEC solution supports different operation modes for the gas sensor to address the necessary power
budget and update rate requirements of the end-application.
Unless mentioned otherwise, the specifications are deduced from new sensors that have been operated for at least five days
mainly in ambient air and consequently have the same history (i.e. same power mode and exposed to the same environment).
Besides ethanol (EtOH) as a target test gas, the sensors are also tested with breath-VOC (b-VOC). The b-VOC mixture, as
listed in Table 5, represents the most important compounds in an exhaled breath of healthy humans. The values are derived
from several publications on breath analysis studies. The composition does not contain species which would chemically react
to ensure that the mixture is stable for at least 6 months. Furthermore, the composition is also limited to species which can
be manufactured in one mixture.
Table 2: Gas sensor parameter specification
Parameter
Symbol
Condition
Min
Typ
Max
Unit
Operational range
1
-40
85
°C
10
95
% r.H.
Supply Current during
heater operation
I
DD
Heater target temperature
320 °C, constant operation
(V
DD
≤ 1.8 V, 25°C)
9
12
13
mA
Peak Supply Current
I
Peak
Occurs within first ms of
switching on the hotplate
15
17
18
mA
Average Supply
Current
(V
DD
≤ 1.8 V, 25°C)
I
DD,IAQ
Ultra-low power mode
0.09
mA
Low power mode
0.9
mA
Continuous mode
12
mA
Response time
2
(brand-new sensors)
τ
33-63%
Ultra-low power mode
92
s
τ
33-63%
Low power mode
1.4
s
τ
33-63%
Continuous mode
0.75
s
Resolution of gas
sensor resistance
measurement
0.05
0.08
0.11
%
Noise in gas sensor
resistance (RMS)
N
R
1.5
%
1
The sensors are electrically operable within this range. Actual performance may vary
2
Response time of unsoldered, brand-new sensors extracted from the sensors’ resistance change in response to a 0.6–60 ppm step of EtOH and a 0.5–15 ppm step of b-VOC at 20 °C, 50%
r.H. and atmospheric pressure.