SHT21P SENSIRION, SHT21P Datasheet - Page 3

• Manufacturer Part Number: SHT21P
• Description: SENSOR, HUMIDITY & TEMP
• Manufacturer: SENSIRION

Specifications of SHT21P

• Humidity Range: 0 - 100% RH
• Sensor Output: Analogue - PWM Interface
• Sensor Terminals: SMD
• Response Time: 8s
• Supply Voltage Range: 2.1V To 3.6V
• Accuracy: 2% RH
• Supply Voltage: 3VDC
• Termination: RoHS Compliant
• Capacitance: 0µF
• Rohs Compliant: Yes
• Sensing Accuracy: 2%
• Operating Temperature Range: -40°C To +125°C
• Msl: MSL 2 - 1 Year

Datasheet SHT21P
Users Guide SHT21P
1 Extended Specifications
For details on how Sensirion is specifying and testing
accuracy performance please consult Application Note
“Statement on Sensor Specification”.
1.1
The sensor works stable within recommended Normal
Range – see Figure 4. Long term exposure to conditions
outside Normal Range, especially at humidity >80%RH,
may temporarily offset the RH signal (+3%RH after 60h).
After return into the Normal Range it will slowly return
towards calibration state by itself. See Section 2.3 “Recon-
ditioning Procedure” for eliminating the offset. Prolonged
exposure to extreme conditions may accelerate ageing.
Figure 4 Operating Conditions
1.2
Maximal tolerance for RH accuracy at 25°C is defined in
Figure 2. For other temperatures maximal tolerance has
been evaluated to be within limits displayed in Figure 5.
Figure 5 Maximal tolerance of relative humidity measurements
given in %RH for temperatures 0 – 80°C.
Please note that above values are maximal tolerances (not
including hysteresis) against a high precision reference
such as a dew point mirror. Typical deviations are at
www.sensirion.com
100
100
80
60
40
20
90
80
70
60
50
40
30
20
10
0
0
Operating Range
RH accuracy at various temperatures
-40
±6
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80
±4
±6
-20
±5
±3
±5
0
±5
±4
±3
±4
±5
20
Normal
Range
±5
±5
40
±3
60
±7
Temperature (°C)
Temperature (°C)
±4
Max.
Range
80
±7
±6
100
±8
Version 1.1 – May 2010
120
±2%RH where maximal tolerance is ±3%RH and about
half the maximal tolerance at other values.
2 Application Information
2.1
The DFN’s die pad (centre pad) and perimeter I/O pads
are fabricated from a planar copper lead-frame by over-
molding leaving the die pad and I/O pads exposed for
mechanical and electrical connection. Both the I/O pads
and die pad should be soldered to the PCB. In order to
prevent oxidation and optimize soldering, the bottom side
of the sensor pads is plated with Ni/Pd/Au.
On the PCB the I/O lands
the package I/O pads. Inward corners may be rounded to
match the I/O pad shape. The I/O land width should match
the DFN-package I/O-pads width 1:1 and the land for the
die pad should match 1:1 with the DFN package – see
Figure 6.
The solder mask
of type Non-Solder Mask Defined (NSMD) with solder
mask openings larger than metal pads. For NSMD pads,
the solder mask opening should be about 120µm to
150µm larger than the pad size, providing a 60µm to 75µm
design clearance between the copper pad and solder
mask. Rounded portions of package pads should have a
matching rounded solder mask-opening shape to minimize
the risk of solder bridging. For the actual pad dimensions,
each pad on the PCB should have its own solder mask
opening with a web of solder mask between adjacent
pads.
Figure 6 Recommended metal land pattern for SHT2x. Values
in mm. Die pad (centre pad) and NC pads may be left floating or
be connected to ground. The outer dotted line represents the
outer dimension of the DFN package.
7
the DFN pads are soldered to.
8
covering the connecting lines.
The land pattern is understood to be the metal layer on the PCB, onto which
The solder mask is understood to be the insulating layer on top of the PCB
Soldering Instructions
8
design for the land pattern preferably is
1.0
7
0.4
should be 0.2mm longer than
2.4
1.0
0.3
3/9