CS5531-AS - 16-Bit, 3.84 kSPS Low-Noise ADC | Cirrus Logic
MPN: CS5531-AS ✗ End of LifeCS5531-AS Overview
An analog-to-digital converter, or ADC, converts continuous analog voltage into a numeric representation for processing, measurement, display, or control. The CS5531 belongs to the sigma-delta ADC class, which uses charge-balance conversion techniques to deliver high effective resolution. Its integrated PGIA places signal amplification and analog conditioning close to the converter, helping preserve low-level sensor signals without relying on a separate analog front end.
Key features include 16-bit resolution, two input channels, a 3.84 kSPS conversion rate, and an ultra-low-noise PGIA. These characteristics make the converter appropriate for weigh-scale transducers, process-control sensors, scientific instruments, and medical monitoring equipment. The sigma-delta architecture is especially useful when measuring slowly changing signals that do not require megahertz-class sampling rates.
The CS5531 uses a charge-balance conversion technique to achieve 16-bit performance while integrating noise rejection and digitization. Its serial interface supports compact system implementation, while programmable gain allows the analog front end to scale small sensor outputs toward the converter's useful input range. Configuration registers can control gain and channel setup, and conversion data is read through the serial interface.
Typical applications include electronic weigh scales, industrial pressure and temperature monitoring, laboratory measurement equipment, and low-level medical signal acquisition. In each case, the PGIA can condition the sensor output before digitization, reducing the number of external analog components and helping preserve signal integrity close to the source.
Designers should follow the manufacturer datasheet for the analog input topology, reference requirements, bypass capacitors, serial interface timing, and printed-circuit-board layout. Pay particular attention to grounding around the reference and converter pins, because high-resolution sigma-delta ADCs can convert layout-induced errors into meaningful measurement errors.
This page organizes the key electrical characteristics, package information, application guidance, documented design considerations, and technically relevant alternatives. It also provides an engineering-focused framework for evaluating the CS5531-AS against related converter options before committing to a production design.
Drop-in alternatives for CS5531-AS — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with CS5531-AS (same form factor and footprint) — differing in Number of Input Channels, Package, Resolution, Interface, Converter Type.
CS5531-ASZ
✅ Drop-InContact for price
View Datasheet →CS5533-ASZ
✅ Drop-InContact for price
View Datasheet →CS5532-ASZR
✅ Drop-InContact for price
View Datasheet →CS5534-ASZR
✅ Drop-InContact for price
View Datasheet →CS5531-AS Maximum Ratings & Electrical Characteristics
| ADC Type | Sigma-delta ADC |
| Resolution | 16 bit |
| Input Channels | 2 inputs |
| Conversion Rate | 3.84 kSPS |
| Integrated Analog Front End | Ultra-low-noise PGIA |
| Supported Signal Type | Low-level unipolar or bipolar |
| Supply Voltage | 5 V |
| Package | 20-SSOP |
| Pin Count | 20 pins |
| Package Pitch | 0.65 mm |
| Mounting Type | Surface Mount |
| Output Interface | Serial |
CS5531-AS 0.65 mm Pin Configuration Guide
Pin configuration for CS5531-AS (0.65 mm package). This analog component features input, output, and power supply pins. Refer to the manufacturer datasheet for offset null, compensation, and enable pin configurations. Ideal for signal conditioning and amplifier circuits.
No detailed pinout data available for CS5531-AS.
Refer to the datasheet for full pin configuration.
Typical Applications
CS5531-AS is suitable for 6 applications: Electronic Weigh-Scale Measurement, Industrial Process-Control Sensing, Scientific and Laboratory Instrumentation, Medical Signal Acquisition, Battery-Powered Sensor Interfaces, Precision Pressure and Level Monitoring.
Electronic Weigh-Scale Measurement
The CS5531-AS suits low-level load-cell and weighing-system measurements because it combines a 16-bit converter, two inputs, and an integrated ultra-low-noise PGIA. The PGIA can condition the small differential signal produced by a strain-gauge bridge close to the transducer, reducing sensitivity to noise introduced across the PCB. Its 3.84 kSPS rate is sufficient for weighing systems that update relatively slowly rather than high-speed force transients. The 20-SSOP package also keeps the analog channel compact, although bridge excitation, filtering, grounding, and calibration remain essential to achieve useful scale accuracy.
Recommended
Industrial Process-Control Sensing
The CS5531-AS is appropriate for process-control inputs such as pressure, level, and temperature transducers that generate small analog voltages. A 16-bit converter provides 65,536 nominal code levels, while the two available inputs can support a measurement channel plus a reference or auxiliary signal. The integrated PGIA reduces the need for a separate low-noise gain stage and helps preserve the integrity of the sensor signal. At 3.84 kSPS, the device favors slowly varying process variables and supervisory measurements rather than fast feedback loops. Firmware must allow adequate settling and digital-filter settling after a channel or gain change.
Recommended
Scientific and Laboratory Instrumentation
The CS5531-AS can serve as the measurement front end in laboratory instruments that digitize low-level sensor outputs while prioritizing resolution over conversion speed. Its 16-bit sigma-delta architecture and ultra-low-noise PGIA are suited to slow, repeatable measurements where averaging and digital filtering can improve usable performance. The two-channel arrangement can support differential sensing or a secondary calibration input. Designers should use a clean reference, carefully decouple the analog supply, and maintain a quiet return path between the PGIA, reference network, and converter to avoid turning PCB leakage or ground gradients into measurement error.
Recommended
Medical Signal Acquisition
The CS5531-AS is relevant to medical monitoring equipment that acquires low-amplitude analog signals with a compact, high-resolution converter. The integrated ultra-low-noise PGIA can reduce the signal path between sensor and ADC, while 16-bit resolution and a 3.84 kSPS conversion rate suit physiological or diagnostic signals that change more slowly than audio-band signals. Medical use still requires application-specific validation, isolation design, input protection, and compliance with the relevant product standards. The converter itself does not establish medical-system compliance; signal-chain testing and risk controls remain the designer's responsibility.
Recommended
Battery-Powered Sensor Interfaces
The CS5531-AS can be used in battery-operated sensor nodes where the measurement changes slowly and conversion energy matters more than maximum throughput. Its 3.84 kSPS rate allows the controller to acquire samples at controlled intervals instead of operating a high-speed converter continuously. The integrated PGIA also simplifies the analog chain by providing gain near the sensor input. Power-budget analysis should include the converter, reference circuit, pull networks, and external regulator, as well as the leakage and settling behavior of the analog input network. Duty-cycled operation must preserve valid calibration and allow sufficient filter settling after each wake-up.
Recommended
Precision Pressure and Level Monitoring
The CS5531-AS fits precision pressure or level monitoring systems where the transducer output is small and varies over time. The two input channels can support complementary sensing, while the integrated PGIA provides adjustable amplification ahead of the 16-bit sigma-delta converter. The 3.84 kSPS throughput is more than adequate for many slowly changing industrial variables and allows digital filtering to suppress out-of-band noise. A practical implementation should account for sensor excitation drift, reference accuracy, input overvoltage, and long cable pickup. Shielding and a clean analog ground region are as important as nominal converter resolution.
Recommended
Recommended Products Summary
Engineering reference data for CS5531-AS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | CS5531 | CS5533-AS | CS5532-AS | CS5534-AS |
|---|---|---|---|---|---|
| Manufacturer | Cirrus Logic | Cirrus Logic | Cirrus Logic | Cirrus Logic | Cirrus Logic |
| Package | 20-SSOP | 20-SSOP | 20-SSOP | 20-SSOP | 20-SSOP |
| Resolution | 16 bit | 16 bit | 16 bit | 24 bit | 24 bit |
| Integrated PGIA | Ultra-low-noise PGIA | Ultra-low-noise PGIA | Ultra-low-noise PGIA | Ultra-low-noise PGIA | Ultra-low-noise PGIA |
| Supported Signal Type | Low-level unipolar or bipolar | Low-level unipolar or bipolar | Low-level unipolar or bipolar | Low-level unipolar or bipolar | Low-level unipolar or bipolar |
| Interface | Serial | Serial | Serial | Serial | Serial |
| Lifecycle Status | Discontinued | Discontinued family | Discontinued family | Discontinued family | Discontinued family |
Key Differentiators
- Integrated ultra-low-noise signal conditioning (vs CS5532-AS)
- Two-input measurement configuration (vs CS5533-AS)
- Low-level unipolar and bipolar measurement support (vs CS5534-AS)
- Conversion speed matched to slow sensor signals (vs CS5531)
Design Notes
Follow the manufacturer reference layout for the analog input, reference, ground, and supply connections. Place input and bypass capacitors close to their associated pins, keep the PGIA and converter return path together, and avoid routing high-current or digital-clock traces beneath the analog inputs. A continuous ground plane is useful, but sensitive analog nodes should not cross digital return paths or split-plane boundaries that create potential gradients.
Treat the PGIA input as a high-impedance analog node. Keep traces short, minimize parasitic capacitance, and use guarding where cable-connected sensors can inject electrostatic noise. Filter at the source when possible instead of relying only on digital filtering, and verify that the external input network does not interfere with converter settling. Differential measurements require matched routing geometry and careful grounding to minimize conversion of common-mode interference into differential error.
Do not assume that nominal 16-bit resolution becomes 16-bit effective accuracy in every system. The usable result depends on reference accuracy, noise, gain error, input source impedance, digital filtering, and calibration. After changing gain or channel, allow the converter and its filter to settle before accepting data. Firmware should also distinguish a valid converted sample from the settling period following startup, mux, or configuration changes.
Decouple the analog supply at the converter with the capacitance and placement specified by the manufacturer datasheet. The reference network also requires careful bypass and grounding because reference noise can dominate the converter's input-referred error. Avoid sharing high-current return paths between the reference, PGIA, and digital interface. If the converter is used in a duty-cycled instrument, verify that the supply remains stable during startup and that the reference has reached its specified settling condition.
Compliance Information
The manufacturer identifies the CS5531/32/33/34 family as discontinued. RoHS, REACH, lead-free, halogen-free, and conflict-minerals status require confirmation from the exact assembled-product documentation.
