Part Number: ADS1115IDGSR, ADS1115IDYNR
Marking Code: BOGI
Function: 16-Bit I²C Analog-to-Digital Converter (ADC)
Package: VSSOP 10 Pin
Manufactures: Texas Instruments
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Overview and Design Guide
The ADS1115 is a precision 16-bit analog-to-digital converter (ADC) designed for applications requiring accurate analog signal measurement while maintaining extremely low power consumption. Integrating a programmable gain amplifier (PGA), internal voltage reference, oscillator, and I²C-compatible digital interface into a compact package, the device significantly reduces external component count and simplifies embedded system design. Its flexible input multiplexer supports both single-ended and differential measurements, making it suitable for a wide variety of sensing applications.
Engineers frequently select the ADS1115 because it combines high measurement accuracy with excellent power efficiency and design flexibility. Programmable input ranges allow both microvolt-level sensor outputs and higher voltage signals to be measured using the same device. Single-shot conversion mode minimizes energy consumption in battery-operated products, while continuous conversion mode supports real-time monitoring applications. The integrated comparator further enables threshold detection without increasing processor workload.
The ADS1115 is widely deployed across industrial automation, portable instrumentation, environmental monitoring, medical electronics, consumer products, battery management systems, and embedded IoT platforms. Whether monitoring temperature sensors, measuring battery voltages, interfacing bridge sensors, or acquiring analog process signals, the device offers an effective combination of precision, low power, and implementation simplicity.
Pinout
Key Electrical Characteristics
- 16-bit delta-sigma ADC providing high-resolution analog measurements.
- Programmable data rates from 8 SPS up to 860 SPS for balancing speed and noise performance.
- Integrated programmable gain amplifier with multiple full-scale input ranges.
- Supports four single-ended inputs or two differential input channels.
- Wide operating supply voltage from 2.0 V to 5.5 V.
- Typical operating current around 150 μA during continuous conversion.
- Internal precision voltage reference minimizes external component requirements.
- Integrated oscillator eliminates the need for an external clock source.
- I²C-compatible interface supporting four selectable device addresses.
- Programmable digital comparator for voltage monitoring and interrupt generation.
- Single-cycle settling allows rapid channel switching.
- Industrial operating temperature range from −40°C to +125°C.
Design Considerations
- Select the PGA gain setting according to the maximum expected input voltage to maximize measurement resolution.
- Ensure input voltages remain within the allowable common-mode and full-scale input limits.
- Use differential inputs for improved noise immunity in sensor applications.
- Place ceramic bypass capacitors close to the VDD pin for stable operation.
- Separate analog signal routing from high-speed digital traces whenever possible.
- Reduce ground impedance by using a continuous ground plane beneath the ADC.
- Consider lower sampling rates when maximizing effective resolution and minimizing conversion noise.
- Take advantage of single-shot conversion mode for battery-powered products.
- Use pull-up resistors appropriate for the selected I²C bus speed and bus capacitance.
- Avoid excessive source impedance, which can degrade conversion accuracy.
Typical Circuit Configurations
- Battery voltage monitoring using single-ended inputs.
- Current sensing through precision shunt resistors using differential inputs.
- Thermistor measurement for temperature monitoring systems.
- Pressure sensor interfaces utilizing bridge-type differential outputs.
- Industrial process monitoring with multiple analog sensor channels.
- Microcontroller expansion when additional analog inputs are required.
- Solar energy monitoring systems measuring panel and battery voltages.
- Portable handheld measurement instruments.
Performance Advantages
- Excellent measurement resolution without requiring external precision references.
- Low power operation extends battery life in portable equipment.
- Flexible PGA supports both low-level sensor signals and higher input voltages.
- Minimal external circuitry simplifies PCB layout and reduces system cost.
- Differential measurement capability improves rejection of common-mode noise.
- Integrated comparator reduces firmware complexity for threshold monitoring.
- Multiple device addresses simplify expansion of analog input channels.
- Small package enables compact embedded designs.
Performance Limitations
- Maximum sampling rate of 860 SPS is not suitable for high-speed data acquisition.
- Delta-sigma architecture introduces conversion latency compared with SAR ADCs.
- I²C bandwidth limits overall throughput in systems with multiple devices.
- Not intended for RF, audio, or high-frequency waveform capture.
- Input bandwidth decreases when operating at lower conversion rates.
- Cannot directly measure voltages exceeding the configured full-scale range.
- Applications requiring simultaneous sampling across multiple channels require different ADC architectures.
Selection Guidelines
- Choose the ADS1115 when high-resolution, low-speed analog measurements are required.
- Verify that the required sampling rate does not exceed 860 samples per second.
- Select the appropriate PGA range based on expected sensor output voltage.
- Evaluate whether differential measurement capability is needed.
- Consider power consumption for battery-operated applications.
- Ensure I²C communication is compatible with the host controller.
- Compare required measurement accuracy against alternative SAR ADC solutions.
- Confirm operating temperature requirements match the intended environment.
- Assess the number of analog channels needed within the system architecture.
- Determine whether the integrated comparator can reduce processor workload.
Typical Applications
- Battery monitoring systems.
- Portable medical instruments.
- Industrial sensor acquisition modules.
- Environmental monitoring equipment.
- Temperature measurement systems.
- Pressure and load cell measurement.
- Smart home automation devices.
- Embedded Linux and microcontroller-based data loggers.
- IoT sensor nodes.
- Factory automation and process control equipment.
Comparison with Similar Components
| Feature | ADS1115 | ADS1015 | Typical 12-Bit SAR ADC |
|---|---|---|---|
| Resolution | 16-bit | 12-bit | 12-bit |
| Maximum Sample Rate | 860 SPS | 3300 SPS | Typically much higher |
| Input Multiplexer | 4 Single-Ended / 2 Differential | Same configuration | Device dependent |
| PGA | Integrated | Integrated | Often external or unavailable |
| Power Consumption | Very Low | Very Low | Generally higher at maximum speed |
| Best Use Case | Precision sensing | Higher-speed monitoring | Fast waveform acquisition |
Frequently Asked Questions
Q1. Why would an engineer choose the ADS1115 instead of the ADS1015?
The ADS1115 offers higher 16-bit measurement resolution, making it better suited for precision sensing applications where small voltage changes must be detected accurately.
Q2. When should differential inputs be used?
Differential mode is recommended when measuring bridge sensors, shunt resistors, or signals that may contain significant common-mode noise.
Q3. How can measurement accuracy be improved?
Use clean power supplies, proper PCB grounding, short analog traces, differential measurements when appropriate, and select the smallest PGA range that safely accommodates the input signal.
Q4. What is the primary advantage of single-shot conversion mode?
Single-shot mode automatically powers down the ADC after each conversion, dramatically reducing power consumption in low-duty-cycle systems.
ADS1115 Datasheet PDF
