In this article we’ll look at three advanced ICs that can help you to monitor the surrounding environment.

Sensors are everywhere these days—homes, cars, portable medical devices, industrial plants, development boards. And as the sensors themselves become more sophisticated and accurate, it’s important for designers to be aware of the latest developments and capabilities.

This article discusses three products that provide information about basic environmental conditions. Two of the measured quantities—namely, temperature and ambient light level—are familiar aspects of everyday life, and thus two of these products are likely to find a place in, for example, consumer electronics, home automation systems, or wearables. The third sensor measures pressure and is probably more relevant to those working with industrial equipment, vehicle systems, or medical technology.

 

Products

Texas Instruments

The OPT3006 is a highly integrated ambient-light sensor. Actually, you will notice that “highly integrated” is a recurring theme in this article. The days of raw analog sensor values and custom signal processing circuitry are fading into obscurity; I suppose you can still do it that way if you want to, but the tide is against you.

 

Image courtesy of Texas Instruments

 

As you can see, the OPT3006 incorporates analog amplification and analog-to-digital conversion; the output is digital data provided via I2C.

An important thing to understand about this sensor is that it is a lux meter; in other words, it measures light intensity according to the optical characteristics of human vision. This is not as easy as you might think, because a basic light-sensitive semiconductor device does not respond to optical wavelengths in the same way as the human eye does. But as you can see in the following plot, TI has managed to very accurately duplicate the typical human spectral response.

 

Image courtesy of Texas Instruments

 

NXP Semiconductors

There is no doubt that you can measure temperature with a discrete thermocouple or thermistor. But that approach seems increasingly archaic when you consider something like the NHS3100 (PDF) from NXP. The “features and benefits” section in the datasheet takes up an entire page.

The NHS3100 is described as a “temperature logger” rather than a temperature sensor, but even that term seems a bit inadequate when you look at the block diagram:

 

Image courtesy of NXP Semiconductor

 

There is indeed an internal temperature-sensing element somewhere in this IC. But obviously, that is just the beginning. It also has an ARM Cortex-M0+ processor, a serial wire debug (SWD) interface, program memory, data memory, GPIOs, interrupts, I2C, reduced-power modes, and an RFID interface. And on top of all that, the temperature sensor offers impressive accuracy: you get ±0.3°C from 0°C to 40°C and ±0.5°C from –40°C to +85°C.

The NHS3100 is surely overkill for many applications, but it’s also a highly integrated and high-performance solution for designs that need the type of functionality that it offers.

 

TE Connectivity

The MS5525DSO (PDF) pressure sensors from TE continue the integration trend. These devices, which are based on a piezo-resistive sensor element, incorporate an analog amplifier and a 24-bit delta-sigma ADC. The sensor data is provided via I2C or SPI.

 

Image courtesy of TE Connectivity

 

The datasheet shows four package options, three of which have one or two handy pressure ports.

 

Image courtesy of TE Connectivity

 

The MS5525DSO devices can perform absolute and differential (as well as gauge and compound) pressure measurements, with a range of 1 to 30 psi. And actually, these chips also have a temperature sensor, so you get two for one.

 

Which sensor ICs have you been using lately? Feel free to share your experiences in the comments.

 

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