Alternative to ADS1115

As embedded systems continue to evolve toward higher precision sensing, lower power consumption, and greater connectivity, analog-to-digital converters (ADCs) have become increasingly critical in system architecture. The ADS1115, a widely adopted 16-bit delta-sigma ADC, has long been favored for sensor measurement, industrial monitoring, environmental data acquisition, and IoT applications due to its integrated programmable gain amplifier (PGA), I²C interface, and relatively simple implementation.

Yet engineers frequently encounter situations where an alternative to ADS1115 becomes necessary. Supply chain disruptions, extended lead times, cost pressures, higher sampling-rate requirements, lower power budgets, or stricter accuracy targets often drive the search for replacement devices. Selecting a suitable alternative requires a deeper understanding of system-level performance than merely matching resolution or interface type.

Why Engineers Replace ADS1115

The ADS1115 occupies a unique position between low-cost MCU-integrated ADCs and high-end precision converters. However, several limitations become apparent in advanced applications.

Typical ADS1115 specifications include:

For many industrial sensors, these specifications remain sufficient. However, applications involving vibration analysis, motor control feedback, high-speed measurement, or multi-channel data acquisition may quickly expose bandwidth limitations.

For instance, a vibration monitoring system measuring frequencies up to 300 Hz should ideally sample at:

300 Hz × 10 = 3000 SPS

The ADS1115's maximum rate of 860 SPS would introduce significant information loss.

Identifying the Critical Replacement Criteria

Resolution Is Not the Whole Story

Many engineers initially compare ADCs based on nominal resolution.

A 16-bit converter theoretically provides:

2¹⁶ = 65,536 quantization levels

However, actual measurement quality depends on Effective Number of Bits (ENOB).

Example:

A higher-resolution device may not always deliver significantly better real-world accuracy if noise performance is poor.

Consequently, alternatives should be evaluated using:

• ENOB

• Integral Nonlinearity (INL)

• Differential Nonlinearity (DNL)

• Input-referred noise

• Gain drift

• Offset drift

rather than relying solely on advertised bit depth.

Sampling Rate Requirements

Sampling speed frequently becomes the primary motivation for migration.

Consider three common scenarios:

The ADS1115 performs exceptionally well in low-bandwidth measurement systems but becomes less suitable when dynamic signals must be captured accurately.

Popular ADS1115 Alternatives

MCP3424

The MCP3424 from Microchip is often viewed as one of the closest functional alternatives.

Key specifications:

Advantages:

• Higher resolution

• Excellent low-frequency noise performance

• Similar firmware architecture

Trade-offs:

• Slower throughput

• Longer conversion times

The MCP3424 is frequently selected in precision temperature measurement and industrial process control systems.

ADS1015

For applications where conversion speed is more important than precision, the ADS1015 offers a practical option.

Engineers often replace ADS1115 with ADS1015 when:

• Cost reduction is required

• High precision is unnecessary

• Faster response is desired

Battery management and portable instrumentation commonly fall into this category.

LTC2497

For measurement-intensive systems, the LTC2497 from Analog Devices provides significantly improved accuracy.

Key features:

• 24-bit architecture

• Integrated multiplexer

• Differential inputs

• Exceptional low-frequency stability

Typical applications include:

• Laboratory instruments

• Weighing systems

• Medical equipment

• Precision process automation

Performance comparison:

Although considerably more expensive, the LTC2497 delivers substantially higher measurement fidelity.

ADS1220

The ADS1220 represents a major performance upgrade while preserving many characteristics familiar to ADS1115 users.

Specifications:

The integrated PGA and high resolution make it attractive for:

• Load cells

• Pressure transmitters

• Precision instrumentation

Many industrial OEMs migrate from ADS1115 to ADS1220 when higher accuracy becomes necessary without moving to significantly more complex ADC architectures.

AD7799

The AD7799 targets demanding sensor applications.

Characteristics:

• 24-bit sigma-delta architecture

• 470 SPS throughput

• Extremely low RMS noise

• Differential inputs

A typical weighing system utilizing a 2 mV/V load cell can achieve sub-gram measurement resolution when paired with AD7799-based front-end circuitry.

Precision Performance Comparison

The following table illustrates practical differences among common alternatives.

The optimal choice depends more on measurement objectives than on absolute specifications.

Industrial Pressure Sensor Migration Example

A manufacturer of industrial pressure transmitters originally utilized ADS1115 for signal acquisition.

System characteristics:

• 4–20 mA transmitter

• 16-bit measurement requirement

• 10 Hz update rate

• Operating range -40°C to +85°C

Field testing revealed:

• Measurement drift during temperature cycling

• Insufficient resolution near calibration limits

Engineers evaluated three alternatives.

Results:

• Calibration accuracy improved from ±0.15% FS to ±0.05% FS

• Noise reduced by approximately 60%

• Sensor repeatability improved by nearly 40%

Although component cost increased by less than $2 per channel, overall product performance improved sufficiently to justify migration.

Power Consumption Considerations

Battery-powered systems require a different evaluation approach.

Current consumption comparison:

In wireless sensor nodes designed for five-year battery life, a higher-performance converter may actually reduce operating life significantly.

For such systems, engineers often prioritize:

• Sleep current

• Wake-up latency

• Conversion efficiency

• Duty cycle optimization

over raw measurement precision.

Interface Compatibility and Firmware Impact

One often-overlooked aspect of ADC replacement is software migration effort.

ADS1115 benefits from:

• Simple I²C communication

• Wide microcontroller support

• Extensive open-source libraries

Switching to SPI-based devices such as ADS1220 or AD7799 may require:

• Driver redevelopment

• Timing validation

• PCB routing modifications

• EMC retesting

Consequently, a technically superior converter may increase engineering costs if firmware compatibility is not considered during evaluation.

Supply Chain and Lifecycle Stability

Recent semiconductor shortages highlighted the importance of second-source planning.

A robust replacement strategy evaluates:

• Product longevity

• Wafer fabrication diversity

• Assembly site redundancy

• Distributor inventory levels

• Historical lead-time behavior

Many OEMs now maintain approved ADC alternatives before product launch rather than reacting after allocation events occur.

Typical sourcing strategy:

Such qualification programs significantly reduce production interruption risks.

Verification Procedures Before Production Release

Successful migration typically includes multiple validation stages.

Electrical Verification

Testing includes:

• Offset error

• Gain error

• Noise spectrum

• ENOB

Environmental Validation

Common conditions:

• -40°C

• 25°C

• 85°C

• 125°C

System-Level Testing

Evaluation focuses on:

• Sensor accuracy

• Calibration retention

• Long-term drift

• EMC behavior

A replacement ADC that performs well on a bench may behave differently when integrated into a complete product.

Supply Support and Quality Assurance Capabilities

Selecting an alternative to ADS1115 involves balancing performance, availability, cost, and long-term reliability. Whether the objective is higher accuracy, faster sampling, lower power consumption, or supply continuity, successful implementation depends on both technical evaluation and dependable sourcing.

Semi can provide comprehensive support for ADC selection, cross-reference analysis, BOM optimization, lifecycle management, and alternative component sourcing across major semiconductor manufacturers. Engineering teams can receive assistance with specification comparison, replacement risk assessment, and long-term procurement planning.

Quality assurance processes typically include:

• Approved supplier management

• Incoming material inspection

• Traceability verification

• Date-code validation

• Packaging inspection

• Electrical testing support

• X-ray inspection services

• Authenticity verification programs

Combined with stable global sourcing channels and strict quality-control procedures, these capabilities help reduce procurement risks while ensuring that alternative ADC solutions meet the performance requirements of industrial, automotive, communication, and embedded applications.

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