www.sensirion.com

Version 2 – December 2011

1/12

Datasheet STS21

Temperature Sensor IC



Fully calibrated





Low power consumption



Excellent long term stability



DFN type package – reflow solderable

Dimensions

Figure 1

Drawing of STS21 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. VSS = GND, SDA = DATA.

Numbering of E/O pads starts at lower right corner (indicated by

notch in die pad) and goes clockwise (compare Table 2).

Sensor Chip

STS21 features a generation 4C CMOSens® chip.

Besides 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 fully RoHS

and WEEE compliant, e.g. free of Pb, Cd and Hg.

Additional Information and Evaluation Kits

Additional information such as Application Notes is

available from the web page www.sensirion.com. For more

information

please

contact

Sensirion

via

info@sensirion.com.

For STS21 two Evaluation Kits are available: EK-H4, a

four-channel device with Viewer Software, that also serves

for data-logging, and a simple EK-H5 directly connecting

one sensor via USB port to a computer.

1.0

1.0

2.4

0.3

0.4

1.1

SCL

SDA

NC

NC

VSS

VDD

Bottom View

3.0

2.2

0.8 typ

0.3 typ

Product Summary

STS21, the new temperature sensor of Sensirion is about

to set new standards in terms of size and intelligence:

Embedded in a reflow solderable Dual Flat No leads

(DFN) package of 3 x 3mm foot print and 1.1mm height it

format.

Using the same CMOSens® technology as Sensirion‟s

successful and industry proven SHT2x humidity and

temperature sensors, the STS21 offers superior

performance and reliability. The ±0.2°C temperature

specification allows for implementation of the STS21 in

applications with high demands on temperature accuracy.

Every sensor is individually calibrated and tested. Lot

identification is printed on the sensor and an electronic

identification code is stored on the chip – which can be

read out by command. Furthermore, the resolution of

STS21 can be changed by command (11bit up to 14bit),

low battery can be detected and a checksum helps to

improve communication reliability.

With made improvements and the miniaturization of the

sensor the performance-to-price ratio has been improved

– and eventually, any device should benefit from the

cutting edge energy saving operation mode.