ADS1115IRUGR

The ADS1115IRUGR is a precision 16-bit delta-sigma analog-to-digital converter from Texas Instruments Burr-Brown product line, designed for low-power and space-constrained applications. With its four-channel input multiplexer, programmable gain amplifier, internal reference, and on-chip oscillator, the ADS1115 provides a complete analog-to-digital conversion solution in an ultra-small 10-pin QFN package measuring only 2mm x 1.5mm. The input multiplexer supports four single-ended inputs or two differential inputs, providing flexibility for various measurement configurations. The programmable gain amplifier offers settings from 2/3 to 16, enabling measurement of signals ranging from millivolts up to the full supply voltage. At the highest gain setting of 16, the full-scale range is only ±0.256V, making it possible to measure very small signals with high resolution. The device operates from a single 2.0V to 5.5V supply, making it compatible with both 3.3V and 5V systems. Communication is accomplished through an I2C-compatible interface supporting standard, fast, and high-speed modes up to 3.4 MHz. An address pin allows up to eight ADS1115 devices to share the same I2C bus. The ALERT/RDY pin provides a programmable comparator function with hysteresis that can trigger an interrupt when measured values exceed user-defined thresholds, or it can indicate when conversion data is ready. An integrated temperature sensor with 0.5C resolution eliminates the need for a separate temperature monitoring IC in many applications. With a supply current of only 150 microamps in continuous conversion mode and 0.5 microamps in sleep mode, the ADS1115 is exceptionally well-suited for battery-powered and energy-harvesting applications. The ADS1115IRUGR is the ultra-small QFN package version, and the R suffix indicates tape and reel packaging.

The ADS1115 uses a delta-sigma (ΔΣ) architecture to achieve high resolution at relatively low sampling rates. At the heart of the converter is a first-order delta-sigma modulator that converts the analog input voltage into a stream of 1s and 0s at a high frequency. The modulator works by repeatedly sampling the input voltage and comparing it with a reference voltage, producing a bitstream whose average value represents the input. The noise from the conversion process is shaped toward higher frequencies (noise shaping), where it can be easily removed by digital filtering. Following the modulator is a digital decimation filter that takes the high-frequency bitstream and converts it into a 16-bit digital output word at the programmed data rate. This filter also provides anti-aliasing, greatly simplifying the requirements for any analog anti-aliasing filter that may precede the ADC. The programmable gain amplifier (PGA) is placed before the modulator, amplifying the input signal to better match the full-scale range of the ADC, thereby increasing the effective resolution for small signals. The input multiplexer allows the ADC to sequentially measure different input channels, with the PGA and modulator being shared resources. The internal reference voltage of 2.048V is generated by a bandgap reference circuit, and the internal oscillator provides the clock for both the modulator and digital filter, eliminating the need for external timing components. The I2C interface allows a microcontroller to configure the device and read conversion results. The programmable comparator monitors the conversion result against user-programmed upper and lower threshold registers, and the ALERT/RDY pin asserts when the result is out of range, with programmable hysteresis and latching behavior. The device also supports a single-shot conversion mode where it performs one conversion, stores the result, and then enters a low-power sleep state – this is how the ultra-low average power consumption is achieved in many applications.

• Battery voltage and current monitoring in portable electronics
• Temperature measurement with thermistors, thermocouples, and RTDs
• Wearable health monitoring devices and fitness trackers
• Smart home and IoT sensor nodes
• Industrial sensor signal conditioning and data acquisition
• Arduino, Raspberry Pi, and embedded system ADC expansion
• Portable test and measurement equipment
• Power supply monitoring and fault detection
• Automotive sensor interfaces (with appropriate protection)
• Low-power energy harvesting sensor systems