ADS1115 ADC Module Symbol
Definition: The ADS1115 ADC Module symbol represents a precision 16-bit, 4-channel, I2C-interface analog-to-digital converter module based on the Texas Instruments ADS1115 IC, shown in circuit diagrams with pins VCC, GND, SDA (I2C data), SCL (I2C clock), and analog inputs A0 and A1, used to add high-resolution analog measurement capability to microcontrollers such as Arduino and Raspberry Pi that lack a built-in ADC or require higher precision than their on-chip ADC provides.
Also known as: ADS1115, ADS1115 ADC, 16-bit ADC module, I2C ADC module, precision ADC breakout, ADS1015 (12-bit variant), 4-channel ADC module, Grove ADC.
What the ADS1115 ADC Module symbol means
The ADS1115 ADC Module symbol marks a precision analog measurement point in a circuit diagram. Unlike the simplified ADC block symbol, the ADS1115 symbol represents a specific, real-world breakout board containing the ADS1115 IC with support components (decoupling capacitors, address resistors, and I2C pull-up resistors). The module accepts analog voltages at inputs A0–A3 (four single-ended or two differential channels) and communicates the 16-bit digital conversion result to a microcontroller over the I2C bus using SDA and SCL.
In schematics the ADS1115 Module symbol indicates that a microcontroller or single-board computer with only digital I/O (or with an insufficient built-in ADC) is being extended with high-precision analog measurement. The I2C address is hardware-configurable (via ADDR pin) to 0x48–0x4B, allowing up to four ADS1115 modules on the same I2C bus, providing up to 16 analog channels.
How to identify the ADS1115 ADC Module symbol
The ADS1115 ADC Module symbol is drawn as a rectangle with supply pins VCC and GND, I2C interface pins SDA and SCL, and analog input pins A0 and A1 (the simplified two-pin representation; full module shows A0–A3). The part name 'ADS1115' or 'ADC Module (16-bit I2C)' is printed inside or beside the block. The reference designator 'U' or 'MOD' may be used. In breadboard-style diagrams the module is often shown as a small breakout PCB outline with labelled header pins.
Function in a circuit
The ADS1115 IC contains a precision programmable-gain amplifier (PGA) that amplifies the differential input voltage before conversion, a sigma-delta (Σ-Δ) 16-bit ADC core, and an I2C interface with a configurable address. The PGA gain is software-adjustable from ±6.144V full-scale to ±0.256V full-scale, enabling measurement of very small voltages with high accuracy. Conversion results are stored in an output register and transmitted as a 16-bit two's complement signed integer over I2C. The device also includes a comparator with programmable thresholds that can assert an ALRT/RDY pin when conversions complete or thresholds are exceeded.
Standards: IEC vs ANSI
| IEC 60617 | The ADS1115 Module symbol follows IEC 60617-12 rectangular block conventions for analog sensor modules. No specific IEC symbol exists for this device; the rectangular block with labelled I2C and analog pins is standard practice. |
|---|---|
| ANSI/IEEE 315 | The ADS1115 Module symbol follows IEEE 315-1975 / ANSI Y32.2 rectangular IC/module symbol conventions. The reference designator 'U' (for IC) or a module-specific designator is used with the part number printed inside. |
| Key difference | Both IEC and ANSI/IEEE representations use identical rectangular blocks for this module symbol. There is no specific graphical difference between the two standards for module-level symbols; the part number and pin labels identify the device. |
Terminals / pins
| Pin | Name |
|---|---|
| vcc | VCC |
| gnd | GND |
| sda | SDA |
| a0 | A0 |
| a1 | A1 |
| scl | SCL |
Typical values
Supply voltage: 2.0V–5.5V. I2C address: 0x48–0x4B (configurable via ADDR pin). Resolution: 16-bit (15-bit effective for single-ended due to sign bit). Data rate: 8–860 SPS (samples per second). PGA full-scale range: ±0.256V, ±0.512V, ±1.024V, ±2.048V, ±4.096V, ±6.144V. Input current: <1nA. Accuracy: ±0.05% FSR (full-scale range). INL: <1 LSB.
Where the ADS1115 ADC Module symbol is used
- Raspberry Pi and similar single-board computers that lack a built-in ADC, reading analog sensors (potentiometers, thermistors, pressure sensors)
- Arduino projects requiring higher precision than the built-in 10-bit ADC, such as precision voltage or current measurement
- Battery voltage monitoring in portable devices where 16-bit resolution provides accurate state-of-charge estimation
- Differential voltage measurement across shunt resistors for high-accuracy current sensing
- pH meter, dissolved oxygen, and water quality sensor interfaces requiring low-noise, high-resolution digitisation
- Thermocouple amplifier output digitisation where millivolt-level signals require PGA and high resolution
- Data logging systems collecting slow-varying physical measurements at high precision over I2C
Example
In a Raspberry Pi soil moisture monitoring project, the ADS1115 Module symbol connects VCC to 3.3V, GND to ground, SDA to GPIO2 (I2C1 SDA), and SCL to GPIO3 (I2C1 SCL); analog input A0 connects to a capacitive soil moisture sensor output and A1 to a 10kΩ thermistor voltage divider. The Pi reads the 16-bit I2C registers at address 0x48 to obtain precision moisture and temperature readings — the ADS1115 Module symbol on the schematic identifies both the precision ADC and the I2C expansion capability.
Key facts
- The ADS1115 ADC Module symbol represents a 16-bit, 4-channel I2C ADC module providing high-precision analog measurement for microcontrollers and single-board computers without a built-in ADC.
- The ADS1115 communicates over I2C using SDA and SCL pins, with a hardware-configurable address (0x48–0x4B) enabling up to four modules on the same bus.
- An integrated programmable-gain amplifier (PGA) with selectable full-scale ranges from ±0.256V to ±6.144V allows measurement of very small differential voltages with high accuracy.
- The sigma-delta (Σ-Δ) ADC architecture delivers 16-bit resolution (15-bit effective single-ended) at data rates from 8 to 860 samples per second.
- Four single-ended input channels (A0–A3) or two differential channel pairs are selectable via I2C configuration register, maximising measurement flexibility.
- The ALRT/RDY pin can be configured as a conversion-ready interrupt or a window comparator alert, eliminating the need for polling in embedded firmware.
- The module symbol is drawn per IEEE 315-1975 / ANSI Y32.2 as a rectangular block with designator 'U', labelled with the part number ADS1115 and I2C plus analog pins.
Frequently asked questions
What does the ADS1115 ADC module symbol mean in a circuit diagram?
The ADS1115 ADC module symbol means a precision 16-bit analog-to-digital converter with I2C interface is used at that point. It converts up to four single-ended or two differential analog voltages into 16-bit digital values readable by a microcontroller over the I2C bus (SDA/SCL). The module is commonly used to add high-resolution analog inputs to Raspberry Pi or Arduino boards.
What does the ADS1115 module symbol look like?
The ADS1115 module symbol is a rectangle labelled 'ADS1115' with supply pins (VCC, GND), I2C pins (SDA, SCL), and analog input pins (A0, A1, and optionally A2, A3). In breadboard or hardware diagrams it may be shown as a physical breakout board outline with a row of header pins. The reference designator 'U' or 'MOD' appears beside the block.
How many pins does the ADS1115 ADC module symbol have?
The ADS1115 module symbol shows six essential pins: VCC (power), GND (ground), SDA (I2C data), SCL (I2C clock), A0 (analog input 0), and A1 (analog input 1). The full IC has additional pins A2, A3, ADDR (I2C address select), and ALRT/RDY (alert/ready output), for a total of ten pins in the MSOP-10 or VSSOP-10 package.
What is the difference between ADS1115 and ADS1015?
The ADS1115 is a 16-bit ADC with a data rate of 8–860 SPS; the ADS1015 is a 12-bit variant with a data rate of 128–3300 SPS. Both share the same I2C interface, register map, and pin-compatible package. Use the ADS1115 where higher resolution is needed (precision voltage/current measurement); use the ADS1015 where higher speed is more important (faster sampling with lower resolution).
What I2C addresses does the ADS1115 use?
The ADS1115 I2C address is configured by connecting the ADDR pin to GND (0x48), VCC (0x49), SDA (0x4A), or SCL (0x4B), giving four possible addresses. This allows up to four ADS1115 modules to coexist on the same I2C bus, providing 16 analog input channels in total.
What standard defines the ADS1115 ADC module symbol?
The ADS1115 module symbol follows IEEE 315-1975 / ANSI Y32.2 for rectangular IC/module symbols in North American schematics. IEC-style schematics use IEC 60617-12 conventions. Both use an identical rectangular block; the ADS1115 part number and pin labels uniquely identify the device.
Can the ADS1115 measure negative voltages?
Yes, in differential mode. When configured as two differential pairs (AIN0–AIN1 or AIN2–AIN3), the ADS1115 measures bipolar voltages within the selected PGA full-scale range (±0.256V to ±6.144V), outputting a signed 16-bit two's complement result. In single-ended mode (AINx referenced to GND) the input must remain above 0V.
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