Data Sheet

Application Note
Rev. 1.00 / July 2014
ZSC31010/ZSC31014
Interfacing with a Gas Sensor
Multi-Market Sensing Platforms
Precise and Deliberate
ZSC31010/ZSC31014
Application Note – Interfacing with a Gas Sensor
Contents
1
2
3
4
5
6
Introduction ....................................................................................................................................................... 3
Digital Interface using the ZSC31014 .............................................................................................................. 3
Analog Interface ............................................................................................................................................... 4
Related Documents .......................................................................................................................................... 5
Glossary ........................................................................................................................................................... 5
Document Revision History .............................................................................................................................. 5
List of Figures
Figure 2.1
Figure 3.1
Gas Sensor Connected to ZSC31014 with Digital Interface .............................................................. 3
Gas Sensor Connected to the ZSC31010 with Analog Out ............................................................... 4
For more information, contact ZMDI via [email protected]
Data Sheet
July 9, 2014
© 2014 Zentrum Mikroelektronik Dresden AG — Rev. 1.00
All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the
prior written consent of the copyright owner. The information furnished in this publication is subject to changes without notice.
2 of 5
ZSC31010/ZSC31014
Application Note – Interfacing with a Gas Sensor
1
Introduction
This application note discusses methods for using ZMDI’s ZSC31010 or ZSC31014 Sensor Signal Conditioner
ICs (SSCs) to interface with typical gas sensors for the purpose of compensating the sensor signal and outputting
the measurement results. Refer to the data sheets for each product for operation details and specifications for the
SSCs.
The ZSC31014 is a sensor signal conditioner for highly accurate amplification and analog-to-digital conversion of
differential full-bridge and half-bridge input signals. Its operating range is -40C to 125C. Measured and corrected
2
*
bridge values are provided at the ZSC31014’s digital output pins, which can be configured as I C™ or SPI.
Section 2 describes an application using the ZSC31014 to compensate the sensor signal from a typical gas
sensor via a digital interface.
The ZSC31010 is a sensor signal conditioner for highly accurate amplification and analog-to-digital conversion of
differential input signals from a full bridge. It features a wider operating range: -50C to 150C. Its output options
include rail-to-rail analog output voltage, absolute analog voltage, and digital ZACwire™* one-wire interface
(OWI). Section 3 describes an application using the ZSC31010 to compensate the sensor signal from a typical
gas sensor via an analog interface.
2
Digital Interface using the ZSC31014
In this application example, the ZSC31014 is used to interface to an SGX SensorTECH®* gas sensor. The gas
sensor consists of a heater and a gas sensor element. The heater current is set through an external 82Ω resistor,
which roughly matches the resistance of the heater resistor. The gas sensor requires a load resistor to ground
(RL). RL is selected to set the output range of the sensor element. The sensor element changes resistance when
exposed to gas and, in combination with RL, forms a half bridge.
Figure 2.1 Gas Sensor Connected to ZSC31014 with Digital Interface
Vsupply
+2.7 to +5.5 V
~82 Ω
MICS-5121
3
4
2
1
1
VSS
VDD
2
Bsink
INT/SS 7
3
VBP
SDA/MISO 6
4
VBN
SCL/SCLK 5
ZSC31014
8
I2C™ or SPI
0.1 F
RL
Ground
* 2
I C™ is a trademark of NXP. SensorTECH® is a trademark of SGX Sensortech, Ltd. ZACwire™, RBiciLite™, RBicLite™ and Sig™ are trademarks of ZMDI.
Data Sheet
July 9, 2014
© 2014 Zentrum Mikroelektronik Dresden AG — Rev. 1.00
All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the
prior written consent of the copyright owner. The information furnished in this publication is subject to changes without notice.
3 of 5
ZSC31010/ZSC31014
Application Note – Interfacing with a Gas Sensor
The ZSC31014 has a differential signal path to support full-bridge measurements into the VBP and VBN pins.
There is an option that sets VBN to an internal VDD/2 reference and thus supports a half-bridge measurement
through VBP. Figure 2.1 shows how the gas sensor interfaces to the VBP pin.
The ZSC31014 has an analog front-end that allows gain adjustment from 1.5 up to 192. A 14-bit ADC converts
the signal to the digital domain, and an integrated math engine performs linearization, calibration, and offset
correction operations. An onboard temperature sensor can be used to temperature compensate the sensor signal.
2
The digital serial output format is I C™ or SPI.
3
Analog Interface
An alternative is to use the ZSC31010 to provide an analog output. This device does not have the option to supply
an internal VDD/2 reference; however, the gas sensor already has a ½ supply divider in the heater section. Any
variation in the divider voltage over temperature can be compensated via calibration using the on-chip temperature sensor available on the ZSC31010. Figure 3.1shows the circuit configuration.
Figure 3.1 Gas Sensor Connected to the ZSC31010 with Analog Output
Vsupply
+2.7 to +5.5 V
~82 Ω
MICS-5121
3
4
2
1 Bsink
2 VBP
VSS 8
SIGTM 7
3 N/C
VDD 6
4 VBN
Vgate 5
1
ZSC31010
Analog Out
0.1 F
RL
Ground
If the gas sensor does not have ½ supply divider available, then a two-resistor divider is required. Typical resistor
values would be 10KΩ.
The ZSC31010 has an analog front-end that allows gain adjustment from 6 up to 48. A 14-bit ADC converts the
signal to the digital domain. An on-board temperature sensor can be used to temperature compensate the sensor
signal. The on-chip DSP applies temperature compensation and then the signal is converted back to analog
through a DAC converter. A buffer amplifier drives the Sig™* pin. The Sig™ pin also supports a one-wire
interface that allows for digital bidirectional communications with the part during calibration.
Data Sheet
July 9, 2014
© 2014 Zentrum Mikroelektronik Dresden AG — Rev. 1.00
All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the
prior written consent of the copyright owner. The information furnished in this publication is subject to changes without notice.
4 of 5
ZSC31010/ZSC31014
Application Note – Interfacing with a Gas Sensor
4
Related Documents
Note: X_xy refers to the current revision of the document.
Document
File Name
ZSC31010 RBicLite™ Data Sheet
ZSC31010_RBic_Lite_Data_Sheet_Rev_X_xy.pdf
ZSC31014 RBiciLite™ Data Sheet
ZSC31014_RBic_iLite_Data_Sheet_Rev_X_xy.pdf
Visit the following ZSC31010 and ZSC31014 product pages on ZMDI’s website www.zmdi.com or contact your
nearest sales office for the latest version of these documents.
www.zmdi.com/zsc31010
www.zmdi.com/zsc31014
5
Glossary
Term
Description
ADC
Analog-to-Digital Converter
DAC
Digital-to-Analog Converter
DSP
Digital Signal Processor
6
Document Revision History
Revision
1.00
Date
Description
July 9, 2014
First release.
Sales and Further Information
www.zmdi.com
[email protected]
Zentrum Mikroelektronik
Dresden AG
Global Headquarters
Grenzstrasse 28
01109 Dresden, Germany
ZMD America, Inc.
1525 McCarthy Blvd., #212
Milpitas, CA 95035-7453
USA
Central Office:
Phone +49.351.8822.306
Fax
+49.351.8822.337
USA Phone 1.855.275.9634
Phone +1.408.883.6310
Fax
+1.408.883.6358
European Technical Support
Phone +49.351.8822.7.772
Fax
+49.351.8822.87.772
DISCLAIMER: This information applies to a product under development. Its characteristics and specifications are subject to change without notice.
Zentrum Mikroelektronik Dresden AG (ZMD AG) assumes no obligation regarding future manufacture unless otherwise agreed to in writing. The
information furnished hereby is believed to be true and accurate. However, under no circumstances shall ZMD AG be liable to any customer,
licensee, or any other third party for any special, indirect, incidental, or consequential damages of any kind or nature whatsoever arising out of or
in any way related to the furnishing, performance, or use of this technical data. ZMD AG hereby expressly disclaims any liability of ZMD AG to any
customer, licensee or any other third party, and any such customer, licensee and any other third party hereby waives any liability of ZMD AG for
any damages in connection with or arising out of the furnishing, performance or use of this technical data, whether based on contract, warranty,
tort (including negligence), strict liability, or otherwise.
European Sales (Stuttgart)
Phone +49.711.674517.55
Fax
+49.711.674517.87955
Data Sheet
July 9, 2014
Zentrum Mikroelektronik
Dresden AG, Japan Office
2nd Floor, Shinbashi Tokyu Bldg.
4-21-3, Shinbashi, Minato-ku
Tokyo, 105-0004
Japan
ZMD FAR EAST, Ltd.
3F, No. 51, Sec. 2,
Keelung Road
11052 Taipei
Taiwan
Phone +81.3.6895.7410
Fax
+81.3.6895.7301
Phone +886.2.2377.8189
Fax
+886.2.2377.8199
Zentrum Mikroelektronik
Dresden AG, Korea Office
U-space 1 Building
11th Floor, Unit JA-1102
670 Sampyeong-dong
Bundang-gu, Seongnam-si
Gyeonggi-do, 463-400
Korea
Phone +82.31.950.7679
Fax
+82.504.841.3026
© 2014 Zentrum Mikroelektronik Dresden AG — Rev. 1.00
All rights reserved. The material contained herein may not be reproduced, adapted, merged, translated, stored, or used without the
prior written consent of the copyright owner. The information furnished in this publication is subject to changes without notice.
5 of 5