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acquisitionZONE Products for the week of August 10, 2009
Texas Instruments Says…
ADS1115: Smallest 16-bit ADC: 70% Smaller Than Competition, For Portable/Industrial/Consumer Applications
Family of data converters reduces overall system space and component count with scalable selection of on-chip integration
Texas Instruments Incorporated (TI) introduced a family of 16-bit analog-to-digital converters (ADCs) packaged in a leadless QFN measuring 2.0 x 1.5 x 0.4 mm – 70 percent smaller than the nearest competition. In addition to significant system space savings, the ADS1115 family provides product options for scalable integration to reduce component count and simplify design. This family supports battery monitoring, portable instrumentation, industrial process control, smart transmitters, medical instrumentation and other industrial and consumer systems.
Designed for precision, power efficiency and ease of implementation, the ADS1115 family performs conversions at programmable data rates up to 860 samples per second (SPS), consuming just 150 µA (typical) of supply current and operating down to 2 V. The ADS1115 is the most highly integrated member of the new family, incorporating an oscillator, low-drift reference, programmable gain amplifier, comparator and four-channel input multiplexer into a tiny package. This family also includes 12-bit versions for increased flexibility.
“Analog customers require ever higher functionality and performance without sacrificing system size and power in order to take their products to the next level,” said Art George, senior vice president of TI’s High-Performance Analog business unit. “By reducing size by 70 percent and delivering a complete family of integration and resolution options, the ADS1115 will help designers achieve a smaller system footprint, lower power, higher performance and easy design implementation.”
EN-Genius Says…
The message here is size, of course. The nearest size competitor is probably the 16 bit 60 sample/s LTC 2453 in a 3mm x 2mm DFN which occupies exactly double the real estate of these parts, in QFN, from TI.
There are three parts in this little family, the ADS1113, ADS1114, and the ADS1115. The basic part, the ADS1113, includes a 16-bit delta-sigma ADC with an I2C interface, an on-chip voltage reference, and an internal oscillator. The ADC core has a differential input with a switched-capacitor delta-sigma modulator followed by a digital filter. There are two available conversion modes: in continuous conversion the converter begins a new conversion immediately the previous one is completed. In single-shot mode the converter completes a conversion on request and stores that value in a register, followed by a power shutdown. The continuous conversion rate can be programmed from 8 sample/s to 860 sample/s.
In the architecture of the ADS1114 a differential input PGA is added before the converter. The full-scale (FS) range is from ±256 mV with a PGA setting of 16, up to ±6.144 V with a PGA setting of 2/3. The input voltage must not exceed the supply rail by more than 300 mV. The ADS1114 also adds a programmable digital comparator that can provide an alert on an external pin.
In the ADS1115 you have all that is in the ADS1114 with a multiplexer added in front. This adds a second differential input (the ADS1115 could be connected for four single-ended inputs, but the basic converter can only be operated with one single-ended input – if you don’t want, or can’t, go differential).
Common-mode rejection is typically 105 dB at dc and with FS set to ±256 mV, falling to 90 dB with FS set at ±6.144 V. The supply voltage range is 2 V to 5.5 V. The current consumption is quoted as identical for all three parts at a typical 150 µA (with a 3.3 V rail) with a shutdown current of 500 nA.
This family should be extremely easy to design in with superb space savings over near comparable device offerings at the 16-bit level. The small price premiums being asked of the ADS1114 and ADS1115 will not be a deterrent to designers who want to use the flexibility of same package integration, especially at the package sizes offered. The comparator addition for monitoring is a nice touch and will be employed in many systems, while the PGA addition greatly simplifies external circuitry. The multiplexer in the ADS1115 will likely be used in one-shot conversion systems. TI also has coming a family of 12-bit ADCs in the same packages (and same power consumption) that will allow sampling up to 3.3 ksample/s. The family is broken down in the same architecture build numbered as the ADS1013, ADS1014, and ADS1015. Both these families will be huge sellers into temperature sensors, pressure and weight monitoring systems, and into portable instruments and loggers, as well as into consumer products.
The ADS1113, ADS1114, and ADS1115 are in production in QFN-10 and MSOP-10 priced at $1.85, $2.00, and $2.25, respectively, all in 1000-piece lots.
Data Sheet
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