CO Sensor Solution

Central to all industrial automation systems is advanced sensor technology that must be both rapid and consistent, as to monitor production lines at short intervals. Texas Instruments, Inc., offers a full-body CO Sensor Solution ideal for use in industrial and consumer applications. Performance is maximized through the combination of the low-power CC2541, delivering Bluetooth BLE communication and configuration to the LMP91000 programmable sensor analog front-end, the TPS61220 step-up converter, and the LM4120 voltage reference.

For a production line to operate efficiently, it must balance speed and precision: Designers of industrial systems must identify the exact moment where speed and reliability have reached the cap, and speed cannot improve any further without sacrificing quality. To ensure this threshold is met, automation systems require an industrial Ethernet system to communicate information with minimal delays, and more importantly, reliable sensors that don’t just monitor, but analyze events in real time.

Industrial automation systems
Four types of components make up all industrial automation systems. The human-machine– interface panels, PLCs, and motor drives push the production line forward; but, it’s the sensors’ job to maintain the accuracy of the entire operation. To process data in real time, sensors must identify a number of factors: an object’s position, weight, acceleration, chemical composition, and temperature, as well as the gases and liquid flow present. Any overlooked aspect will result in stalling production and thereby decrease the bottom line.

Key requirements of sensors and transmitters
The continuous observation and maintenance of key variables such as temperature, pressure, flow, etc., is extremely vital to the managing of industrial automation and process control. With that being said, conditioning low signal levels amid high noise and high surge voltage is the principal challenge of sensing equipment.

These specific needs dictate the inclusion of low-noise and low-drift precision programmable gain amplifiers, instrumentation amplifiers, and the use a specific common-mode voltage. In addition, the rate of change of the measured signal is minor, prompting the use of high-resolution precision delta-sigma converters. Furthermore, sensing equipment requires low power consumption because most are still powered by a traditional 4 to 20-mA loop.

A newly adopted standard in sensing equipment is digital connectivity. For the added benefits of continuous monitoring, fault diagnostics, start-up time reduction, and improved productivity and efficiency, features such as PROFIBUS, IO-Link, CAN, and wireless connectivity are becoming integral.

Challenges
One of the biggest challenges faced by industrial automation systems overall, is that they rely on the current state of standards for control systems technology. The response-time and accuracy of these systems are bottlenecked by the same technology that defines it, meaning that automation systems will only improve as do control system standards which govern them.

A second challenge is presented by overabundance of solutions on the market which in turn create unnecessary complexity and cost. Each popular communication protocol is backed by one or more major suppliers of PLCs, HMIs, and motor drives. As a result, incorporating a solution with multiple elements involves adopting multiple protocols to accommodate those elements, thus raising the cost and complexity of the solution.
TI rises to the occasion by introducing technology that stream lines and connects communication systems.
The company’s portfolio of solutions includes industrial grade sensors that are not only tailored for various parameters such as gas, flow, pH levels, weight, etc, but are future orientated with their focus on digital connectivity.

Chemical/gas sensor solution
TI's chemical/gas sensor solution suite includes low-power pin-compatible sensors that are also appropriate for battery-powered applications. Chemical and gas sensors should never be shut off, must be operational at all times under most circumstances, and must be of small size to easily integrate into modules. The LMP91000 offers additional advantages over the typical market solution that requires external JFET, different boards and settings, external temperature sensors, and a DAC on top of it all.

Components LMP91000, CC2541, LM4120 and TPS61220 form the solution suite.

Broad range of industry certifications
The entire solution runs off of a CR2032 coin-cell battery and complies with the wireless certifications of EN 300 328, FCC 15.247, and IC RSS-210. With regards to EMC certification, the platform complies with FCC Federal Communication Commission Part 15 Class B, IC – Industry Canada Ices-003 Class B, and EN 301 489-17.

LMP91000
LMP91000 is a programmable analog front-end (AFE) that supplies a complete signal path solution between a sensor and microcontroller, generating output voltage proportional to the cell current. LMP is an excellent choice for micropower electrochemical sensing; its flexibility allows the support of multiple electrochemical sensors, such as three-lead toxic gas sensors and two-lead galvanic cell sensors, with one consolidated design.

Micropower applications operate effectively on the LMP91000 as the device functions over voltage range between 2.7 and 5.25 V. Although the total consumption is less than 10 μA, additional savings is possible by switching off the TIA amplifier and shorting the reference electrode to operate with an internal switch. The extremely low power guarantees extra battery life.

CC2541 2.4GHz Bluetooth
The CC2541 allows the creation of robust network nodes using a low bill-of-material cost. It is a system-on-chip solution power optimized for Bluetooth low energy and 2.4-GHz applications. When paired with systems requiring low power consumption, the CC2541 offers short transition between multiple operating modes to yield added low power consumption.

Furthermore, the solution merges powerful support features and peripherals through the union of a leading RF transceiver with an industry standard enhanced 8051 microcontroller, in-system programmable flash memory, 8-Kbyte RAM, and more.

LM4120
The LM4120 is a precision low power lower dropout bandgap voltage reference. Voltage references produce a constant voltage over time regardless of temperature, load, or power supply changes, thus rendering the LM4120 ideal for battery powered portable devices.

The device operates within an input voltage ranging from as low as 2V, to as high as 12V, and consumes only 160 µA of supply current. If power mode is enabled, the current will further drop to as low as 2 µA. Subsequently, LM4120 is very flexible, featuring two grades(A and Standard) and seven voltage options. The device performance is ensured over the industrial temperature range (−40°C to +85°C), while certain specs are ensured over the extended temperature range (−40°C to +125°C).

TPS61220
The last component of TI's complete CO Sensor Solution is the TPS61220 − a low input voltage step-up converter existing in a 6 pin SC-70 package and measuring only 2mm x 2mm. The device is a power-supply solution for all products powered by the following batteries types: single-cell, two-cell, or three-cell alkaline, NiCd or NiMH, a one-cell Li-Ion or a Li-polymer battery. Moreover, TPS61220 protects circuits against output overvoltage, overtemperature, and input undervoltage lockout.

TPS61220 performs at up to 95% efficiency under typical operating conditions. It includes an operating input voltage ranging from 0.7 to 5.5 V, and is available in either an adjustable output voltage or a fixed output voltage version. The output voltage of the adjustable variety is programmable within the range of 1.8 to 5.5 V using an external resistor divider, but is set internally in the fixed output version.