SI7021-A20 Datasheet, PDF (5/36 Pages) Silicon Laboratories – IC HUMIDITY AND TEMPERATURE SENSOR

Si7021-A20
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
Symbol
Test Condition
Min
Conversion Time¹
t_CONV
12-bit RH
—
11-bit RH
—
10-bit RH
—
8-bit RH
—
14-bit temperature
—
13-bit temperature
—
12-bit temperature
—
11-bit temperature
—
Powerup Time
t_PU
From VDD ≥ 1.9 V to ready for a
—
conversion, 25 °C
From VDD ≥ 1.9 V to ready for a
—
conversion, full temperature range
After issuing a software reset
—
command
Typ
Max Unit
10
12
5.8
7
3.7
4.5
2.6
3.1
ms
7
10.8
4
6.2
2.4
3.8
1.5
2.4
18
25
—
80
ms
5
15
Notes:
1. Initiating a RH measurement will also automatically initiate a temperature measurement. The total conversion time will
2.
be
No
tc_{CoOnNvVe(rRsHio)n+ortCIO2CNVt(rTan).saction}
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, and Read Firmware Version. Duration
is <100 μs when I²C 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.
Table 3. I²C Interface Specifications¹
1.9  V_DD  3.6 V; T_A = –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
V_HYS High-to-low versus low-to- 0.05 x V_DD —
—
V
high transition
SCLK Frequency²
SCL High Time
SCL Low Time
Start Hold Time
Start Setup Time
f_SCL
t_SKH
t_SKL
t_STH
t_STS
—
—
400 kHz
0.6
—
—
μs
1.3
—
—
μs
0.6
—
—
μs
0.6
—
—
μs
Notes:
1. All values are referenced to V_IL and/or V_IH.
2. Depending on the conversion command, the Si7021 may hold the master during the conversion (clock stretch). At
above 100 kHz SCL, the Si7021 may also 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