Free tools Windows power users keep installed
One-click scans. No signup required.
An analog-to-digital converter (ADC) turns a changing real-world signal—such as a sensor’s voltage—into digital codes that a computer or controller can process. To understand whether an ADC is suitable, look beyond its bit count: sampling rate, input range, architecture, accuracy, latency, and the surrounding analog circuitry all matter.
What an ADC does
Many sensors and other sources produce analog signals: values that vary continuously over time. An ADC measures that signal at intervals and represents each measurement as a binary code. Digital hardware can then store, analyze, transmit, or use those values in a control system.
The converter is usually one part of a larger chain. A sensor, signal-conditioning circuit, input filter, voltage reference, ADC, and software can all affect the final measurement. A converter’s nominal resolution alone does not describe the accuracy of that whole system.
How sampling and quantization work
Sampling divides time into measurements
The ADC takes samples at discrete time intervals. The rate at which it does this is the sampling rate, usually expressed in samples per second. A faster rate captures changes more frequently, but it also increases the amount of data and may affect power, cost, and processing requirements.
#1 Best Overall
- 2PCS ADS1115 16 Bit IIC I2C analog to digital converter Module Precision ADC Converter 4 Channel Development Board Programmable Gain Amplifier 2.0V to 5.5V for Arduino Raspberry Pi
- Interface Type: I2C
- Channels: 4 Channel AN0 AN1 AN2 AN3 or 2 differential inputs
- Input voltage: 2.0-5.5v
- Channel input voltage :0-VDD
The rate must suit the signal’s bandwidth. Analog Devices’ Nyquist theorem glossary states that the sampling rate must be at least twice the signal’s maximum bandwidth for it to be represented without aliasing. This condition does not remove the need for filtering: unwanted frequencies above the intended signal band can fold into the measured band during sampling. The appropriate filter depends on the signal and converter.
Quantization maps samples to codes
Although an analog input can take a continuum of values, a digital output has a finite set of codes. Quantization assigns each sampled value to one of those codes. An input between available code levels cannot be represented exactly.
Rank #2
- WIDE SUPPLY RANGE: 2.0V to 5.5V bits of resolution offered in an ultra-small, leadless
- INTERNAL PGA up to 860 samples per second (SPS). An onboard PGA is available on the ADS1114 and ADS1115 that
- Single-Shot Mode: Auto Shut Down; Programmable data rate: 8sps-860sps
An N-bit ADC has 2N possible codes. For a defined full-scale input range, the ideal voltage step, or one least significant bit (LSB), is the range divided by 2N. For example, if a 12-bit ADC uses a 0–4.096 V full-scale range, the ideal step is 4.096 V ÷ 4096 = 1 mV. That calculation describes ideal code spacing for this range; it does not guarantee 1 mV measurement accuracy. Actual coding conventions and usable input ranges vary by device.
Resolution is not the same as accuracy
Resolution describes how many output codes are available. Accuracy describes how close the reported measurement is to the true input, under defined conditions. More bits can provide finer code spacing, but do not by themselves make a measurement more accurate.
Quick wins for a faster PC:
Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →Rank #3
- [HIGH CONVERSION] Experience unparalleled performance with our 16-bit ADC module, designed for analog-to-digital conversion. With a sampling that captures data with remarkable accuracy, your projects will from detailed readings in every application.
- [VERSATILE INPUT OPTIONS] This ADC module supports up to 4 single-ended or 2 differential inputs, giving you the flexibility to work with various analog signals. Its programmable comparator enhances functionality, making it ideal for diverse use cases.
- [FAST DATA RATE] Unlock exceptional data transfer rates with programmable speeds from 8sps to 860sps. This adaptability ensures that your readings are timely and accurate, suitable for applications requiring quick response times.
- [EASY INTEGRATION] Designed with convenience in mind, the I2C interface simplifies connections to your 3/2/B+ projects. The pin-selectable address configuration allows for seamless integration within your existing setups, streamlining your development process.
- [COMPACT DESIGN] Our ultra-compact MSOP-10 package ensures that the ADC module fits neatly into your projects without taking up excessive space. This thoughtful design makes it an excellent choice for tight-fitting applications and embedded systems.
Errors can come from converter nonlinearity, offset, gain, noise, reference-voltage variation, temperature, and the sensor or analog front end. Input settling and circuit design matter too. Analog Devices’ ADC error discussion illustrates how an error budget can relate converter errors to code size; its 12-bit, 4-LSB example is illustrative, not a general performance statistic. The article also cautions that AC performance tests may use non-standardized conditions, so compare data-sheet results only when the test conditions are comparable.
Common ADC architectures and their tradeoffs
Architecture describes how a converter performs its conversion. These broad tendencies help narrow choices, but products overlap: use the target device’s data sheet and your system requirements to decide.
Rank #4
- 2PCS PWM to Voltage Conversion Module 0%-100% To 0V-10V For PLC MCU Digital to Analog Signal PWM Adjustable Converter Power Module
- PWM to Voltage Conversion Module 0%-100% To 0V-10V
| Architecture | Typical strength | Tradeoff to consider |
|---|---|---|
| Flash | Very fast conversion using parallel comparisons. | The number of comparators rises sharply with resolution, so flash is not a general-purpose default. |
| SAR (successive approximation) | Common in data acquisition and multiplexed measurement; the conversion result is available at the end of conversion without pipeline delay. | Input acquisition and settling requirements matter, as do the front end and the specific device’s performance. |
| Pipeline | High throughput for faster signals, including instrumentation and communications applications. | Conversion takes place in stages, so account for latency and system timing. |
| Sigma-delta | Often suited to high-precision measurements at lower input bandwidth, using oversampling, noise shaping, and filtering. | Greater latency can make it a poor match for rapidly multiplexed inputs. |
How to choose an ADC for a project
Start with the measurement and system constraints, then compare candidates’ full specifications. Analog Devices frames the decision with the questions “How do you pick one?” and how important speed, power, and signal accuracy are for the signals being measured, in its ADC selection guide.
- Define the signal. Identify its bandwidth, expected amplitude, input-voltage range, and whether it is unipolar, bipolar, or differential.
- Set sampling and timing needs. Choose a sample rate suited to the signal bandwidth and filtering, then determine whether conversion latency is acceptable.
- Count channels and account for switching. Decide how many inputs are needed and whether they will be multiplexed. Check the acquisition and settling requirements when switching between channels.
- Set accuracy and resolution requirements. Determine the measurement tolerance you need, then evaluate resolution alongside linearity, offset, gain, noise, reference, and temperature specifications.
- Match the architecture and interface. Consider whether the speed, latency, and input-bandwidth tendencies of flash, SAR, pipeline, or sigma-delta fit the application. Confirm that the digital interface works with the controller or processor.
- Check the implementation details. Review power, reference-voltage requirements, input-drive needs, analog filtering, data-sheet test conditions, and cost. Include the sensor and analog front end in the accuracy budget.
When an evaluation board helps
An ADC evaluation or development board is an optional way to explore hardware and test a converter in a prototype. It is not needed to understand ADC fundamentals. Before selecting a board, check its input range, resolution, sample rate, channel count, interface, reference and input circuitry, software, host compatibility, and included components. Confirm current product documentation and availability before buying; no particular board or compatibility claim applies to every ADC.
Recommended Free Tools
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
