SI7015-A10 Datasheet, PDF (20/39 Pages) Silicon Laboratories – Excellent long term stability

Si7015-A10
5.1.2. Performing a Temperature Measurement
The following steps should be performed in sequence to take a temperature measurement:
1. Set START (D0) and TEMP (D4) in CONFIG (register 0x03) to begin a new conversion, i.e., write CONFIG
with 0x11
2. Poll RDY (D0) in STATUS (register 0) until it is low (=0). This must be done at least once prior to reading
results even if the host waits longer than t_CONV.
3. Read the upper and lower bytes of the temperature value from DATAh and DATAl (registers 0x01 and
0x02), respectively
Table 13 shows the format of the 14-bit temperature result. This value may be converted to °C using the following
equation:
TemperatureC
=


T_-----E_-3---M2_-----P_{---}
– 50
where TEMP is the measured value returned in DATAh:DATAI.
Table 14 shows the 14-bit values that correspond to various measured temperature levels.
Table 13. 14-Bit Temperature Result Available in Registers 1 and 2
DATAh
DATAI
D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0
14-Bit Temperature Code
The above sequence assumes normal mode, i.e., t_CONV = 5.8 ms (typical). Conversions may be performed in fast
mode. See Section “5.1.4. Fast Conversion Mode”.
5.1.3. Entering Low-Power Mode
Either of the following sequences can be used to place the Si7015 into its low-power standby mode following an
RH conversion:
Option A:
Bring CSb high. This puts the Si7015 in low-power mode and disables I²C communication. This is similar to Si7005
except that the response to CSb high takes only a few usec and the VDD current is <1 µA (as opposed to Si7005
which can take >1second and can have VDD current of up to 100 µA).
Option B:
1. Poll /RDY until it returns zero, indicating that the conversion is finished.
2. Read the results of the RH conversion from DATAh:DATAl.
3. Clear the start bit (START) by writing 0x0 to register 3.
4. Clear the start bit (START) a second time by again writing 0x0 to register 3.
The Si7015 does enter its low-power standby mode following a temperature conversion. No action is required in
this case. However, please note that doing a temperature conversion following an RH conversion will not put the
Si7015 in low power state.
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Rev. 1.0