www.sensirion.com

Version 4 – May 2014

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Datasheet SHT21P

Humidity and Temperature Sensor IC



Fully calibrated



Analog output, PWM interface



Low power consumption



Excellent long term stability



DFN type package – reflow solderable

Dimensions

Figure 1: Drawing of SHT21P sensor package, dimensions

are given in mm (1mm = 0.039inch), tolerances are ±0.1mm.

The die pad (center pad) is internally connected to VSS. The NC

pads must be left floating. Numbering of E/O pads starts at lower

right corner (indicated by notch in die pad) and goes clockwise

(compare Table 2).

Sensor Chip

SHT21P features a generation 4C CMOSens® chip.

Besides the capacitive relative humidity sensor and the

band gap temperature sensor, the chip contains an

amplifier, A/D converter, OTP memory and a digital

processing unit.

Material Contents

While the sensor itself is made of Silicon the sensors’

housing consists of a plated Cu lead-frame and green

epoxy-based mold compound. The device is free of Pb, Cd

and Hg – hence it is fully RoHS and WEEE compliant.

Additional Information

Additional information such as Application Notes is

available from the web page www.sensirion.com/sht21.

For more information please contact Sensirion via

info@sensirion.com.

1.0

1.0

2.4

0.3

0.4

1.1

SCL

SDA

NC

NC

VSS

VDD

Bottom

View

3.0

2.2

1.4 max

0.3 typ

Product Summary

The SHT21 humidity and temperature sensor of Sensirion

has become an industry standard in terms of form factor

and intelligence: Embedded in a reflow solderable Dual

Flat No leads (DFN) package of 3 x 3mm foot print and

1.1mm height it provides calibrated, linearized sensor

signals in analog Pulse Width Modulated (PWM) format.

The SHT2x sensors contain a capacitive type humidity

sensor, a band gap temperature sensor and specialized

analog and digital integrated circuit – all on a single

performance in terms of accuracy and stability as well as

minimal power consumption.

PWM signal runs on a base frequency of 120Hz, the data

signal is provided on SDA line. Pulling SCL high or low

allows for switching between humidity and temperature,

respectively. The sensor measures twice per second. The

PWM signal may be converted to an analog ratiometric

interface by adding a low pass filter.

Every sensor is individually calibrated and tested. Lot

identification is printed on the sensor.

With this set of features and the proven reliability and

long-term stability, the SHT2x sensors offer an

outstanding performance-to-price ratio. For testing SHT2x

two evaluation kits EK-H4 and EK-H5 are available.