ADC-20 and ADC-24

The PicoLog ADC-20 and ADC-24 are precision USB data loggers developed for applications where high measurement resolution, low noise and flexible multichannel acquisition are required.

The ADC-20 provides 20-bit resolution with four true differential inputs that can alternatively be configured as up to eight single-ended channels. The ADC-24 increases resolution to 24 bits and provides eight true differential inputs or up to sixteen single-ended channels.

This flexible channel configuration allows engineers to select differential measurements for improved noise rejection or use additional single-ended channels where a larger channel count is required.

High-Resolution Voltage Measurement

The ADC-20 and ADC-24 are designed to detect very small changes in voltage.

Key model differences include:

• ADC-20: 20-bit ADC resolution
• ADC-24: 24-bit ADC resolution
• ADC-20: 4 differential or 8 single-ended inputs
• ADC-24: 8 differential or 16 single-ended inputs
• ADC-20 gain error: 0.2% of reading
• ADC-24 gain error: 0.1% on ±39 mV to ±1250 mV ranges and 0.2% on the ±2500 mV range

The higher resolution and additional low-voltage ranges of the ADC-24 make it particularly suitable for precision sensor measurements and applications involving small signal levels.

Programmable Bipolar Input Ranges

The two models have different voltage-range capabilities.

ADC-20 Input Ranges

• ±1250 mV
• ±2500 mV

ADC-24 Input Ranges

• ±39 mV
• ±78 mV
• ±156 mV
• ±312/313 mV
• ±625 mV
• ±1250 mV
• ±2500 mV

The lower ranges available on the ADC-24 allow small sensor outputs to use more of the converter's available measurement range, improving effective resolution in low-level signal applications.

True Differential and Single-Ended Inputs

Each physical differential input can be configured either as:

• One differential measurement channel, or
• Two single-ended channels

Differential measurement is useful when measuring low-level signals in electrically noisy environments because it measures the voltage difference between two inputs rather than referencing only one signal to common.

Typical applications include:

• Sensor measurements
• Bridge circuits
• Laboratory instrumentation
• Low-level voltage measurements
• Process monitoring
• Research experiments

High Noise Rejection

Pico specifies 120 dB typical noise rejection at 50/60 Hz.

This is particularly beneficial in precision measurement environments where mains-frequency interference could otherwise affect small sensor signals or long-duration voltage measurements.

Galvanic Isolation from the Computer

The ADC-20 and ADC-24 provide galvanic isolation between the measurement inputs and PC ground up to ±30 V.

The analog ground and digital ground are also isolated.

This isolation helps reduce measurement problems caused by ground loops and electrical noise transferred through the connected computer.

The units do not provide channel-to-channel isolation, so this distinction should be considered when planning measurements involving multiple independent electrical systems.

Selectable Conversion Speed

Both models support software-selectable conversion times per channel of:

• 660 ms
• 340 ms
• 180 ms
• 100 ms
• 60 ms

Longer conversion times provide higher noise-free resolution, while shorter conversion times allow measurements to be updated more quickly.

This allows engineers to select an appropriate balance between acquisition speed and effective measurement resolution according to the application.

Noise-Free Resolution

The effective noise-free resolution depends on the selected voltage range and conversion time.

For example, the ADC-24 can provide up to 20 bits of noise-free resolution on selected ranges at the longest conversion time.

At faster conversion rates, effective noise-free resolution is reduced, allowing users to trade resolution for speed according to measurement requirements.

ADC-24 Digital I/O

The ADC-24 includes four bidirectional digital I/O channels.

These use 3.3 V CMOS levels and can be used in compatible applications for functions such as:

• Alarm control
• External switching
• Test automation
• Digital status monitoring
• Trigger-related control
• Interfacing with external circuits

The ADC-20 does not include digital I/O channels.

Reference Voltage Outputs

Both models provide reference outputs that can be useful when powering or interfacing suitable sensor circuits:

• +2.5 V ±2.5 mV at 2 mA
• +5 V ±1.0 V at 2 mA
• −5 V ±1.5 V at 2 mA

These reference outputs can support compatible signal-conditioning and sensor circuits within the manufacturer's stated current limits.

Optional ADC-20/ADC-24 Terminal Board

Pico offers a dedicated ADC-20/ADC-24 Terminal Board for easier sensor and signal connection.

The terminal board provides screw-terminal connections so that sensor wires can be attached without soldering. It also provides space for additional components that can be used to create signal-conditioning circuits.

Typical uses include:

• Temperature measurement circuits
• Voltage-divider networks
• Sensor interfacing
• Custom signal conditioning
• Educational experiments
• Prototype DAQ systems

The terminal board is an accessory and should only be described as included when the selected package specifically contains it.

PicoLog 6 Data Logging Software

The ADC-20 and ADC-24 work with PicoLog 6, Pico Technology's data acquisition and logging software.

PicoLog 6 supports:

• Real-time data acquisition
• Graph and table displays
• Multiple measurement channels
• Calculated channels
• Channel scaling
• Programmable alarms
• Capture annotations
• Multiple graph axes
• Long-duration PC logging
• CSV export
• PDF reporting
• Multiple Pico data loggers on one computer

PicoLog also supports mixed systems containing different compatible Pico data loggers.

PicoLog Cloud

The ADC-20 and ADC-24 support PicoLog Cloud, allowing measurement captures to be uploaded to Pico's cloud service.

Data can then be shared through a browser-accessible link on:

• PCs
• Smartphones
• Tablets

Pico also provides a Cloud API that can transfer live captured data into compatible third-party software or databases.

This can be useful for remote data review, distributed engineering teams and connected monitoring applications.

PicoSDK for Custom DAQ Applications

Pico provides PicoSDK software drivers and programming support, allowing the ADC-20 and ADC-24 to be integrated into custom measurement applications.

Typical uses include:

• Automated test equipment
• Custom laboratory software
• Industrial monitoring systems
• Production test applications
• Research instrumentation
• Database-integrated DAQ systems

Typical Applications

The Pico ADC-20 and ADC-24 are suitable for:

• Precision voltage measurement
• Multichannel data acquisition
• Sensor and transducer monitoring
• Low-level signal measurement
• Laboratory research
• Industrial process monitoring
• Environmental measurements
• Electronic design verification
• Battery and power-system experiments
• Educational laboratories
• Long-duration data logging
• Production test systems
• Automated measurement systems
• Scientific experiments
• Custom DAQ applications