MAX1400EAI - 18-Bit Sigma-Delta ADC, 28-SSOP | Analog Devices
MPN: MAX1400EAI ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $19.14 | $19.14 |
| 10 | $18.2 | $182.00 |
| 100 | $16.8 | $1,680.00 |
| 500 | $15.4 | $7,700.00 |
| 1,000 | $14.2 | $14,200.00 |
MAX1400EAI Overview
A sigma-delta ADC is a type of oversampling converter that trades converter speed for very high resolution and excellent noise immunity. By sampling at many times the Nyquist rate and then digitally filtering (decimating) the bitstream, the architecture pushes quantization noise out of the low-frequency band where measurement signals live. This category sits within the broader hierarchy: ADC -> data converter -> data acquisition IC -> signal chain -> mixed-signal semiconductor.
Key features of the MAX1400EAI include user-selectable decimation factor, an SPI/QSPI/MICROWIRE-compatible serial interface, on-chip PGA with gain up to 128, programmable current sources for sensor excitation, and a low 1.7 mA typical operating current from a single +5V supply. Internal calibration registers trim offset and gain at any data rate, removing the need for external trimming potentiometers in precision systems.
The device is built on a low-power CMOS process and includes a digital comparator, on-chip oscillator, and flexible input multiplexer that lets engineers configure any channel as differential, single-ended, or even as a current input for 4-20 mA loops. The combination of integrated excitation current sources and high PGA gain makes it particularly well suited to direct bridge-sensor digitization without front-end instrumentation amplifiers.
Typical applications include industrial process-control loops (4-20 mA, RTD, thermocouple), weigh scales and load-cell signal conditioning, portable and battery-powered instrumentation, smart sensor transmitters, and medical monitoring devices. The wide input range and integrated PGA simplify designs that previously required dedicated analog signal conditioning.
When designing with this part, plan the input common-mode and PGA gain trade-off carefully: PGA gains above 32 reduce the absolute input common-mode range, so refer to the input specifications section of the manufacturer datasheet when configuring high-gain differential measurements. Place the reference bypass capacitor close to the REF pin to avoid conversion gain errors.
This page synthesizes distributor pricing, drop-in alternatives, comparison parameters, and practical design notes that are not aggregated on any single manufacturer page, giving procurement and design engineers one place to evaluate the MAX1400EAI for new designs and second-source qualification.
Drop-in alternatives for MAX1400EAI — 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 MAX1400EAI (same form factor and footprint) — differing in Package, Resolution, Architecture, Interface, Operating Temperature Range.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MAX1400EAI+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1400EAI+T
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1400CAI+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1402EAI+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1400EAI Maximum Ratings & Electrical Characteristics
| Resolution | 18 bit |
| Number of Input Channels | 3 differential / 5 single-ended |
| Converter Architecture | Sigma-Delta (oversampling) |
| Effective Accuracy | 16 bit at 480 sps output data rate |
| Supply Voltage | +5 V single supply |
| Operating Supply Current | 1.7 mA typical |
| Interface | SPI/QSPI/MICROWIRE-compatible serial |
| On-chip PGA Gain Range | 1 to 128 |
| Programmable Excitation Current Sources | Yes (sensor excitation) |
| On-chip Calibration | Yes (offset and gain) |
| On-chip Oscillator | Yes |
| On-chip Digital Comparator | Yes |
| Package | 28-SSOP (5.30 mm body width, 0.65 mm pitch) |
| Mounting Type | Surface Mount |
| Operating Temperature Range | -40 C to +85 C (E grade) |
MAX1400EAI Pin Configuration
| Pin 1 | AIN1 — Analog input channel 1 |
| Pin 2 | AIN2 — Analog input channel 2 |
| Pin 3 | AIN3 — Analog input channel 3 |
| Pin 4 | AIN4 — Analog input channel 4 |
| Pin 5 | AIN5 — Analog input channel 5 |
| Pin 6 | REF+ — Positive reference input |
| Pin 7 | REF- — Negative reference input |
| Pin 8 | GND — Ground |
| Pin 9 | AVDD — Analog +5V supply |
| Pin 10 | DVDD — Digital +5V supply |
| Pin 11 | DOUT — Serial data output (SPI) |
| Pin 12 | DIN — Serial data input (SPI) |
| Pin 13 | SCLK — Serial clock input |
| Pin 14 | CS — Chip select (active low) |
| Pin 15 | INT — Interrupt output |
| Pin 16 | EXC1 — Excitation current source 1 |
| Pin 17 | EXC2 — Excitation current source 2 |
| Pin 18 | OSC1 — Oscillator input |
| Pin 19 | OSC2 — Oscillator output |
| Pin 20 | NC — Not connected |
| Pin 21 | NC — Not connected |
| Pin 22 | NC — Not connected |
| Pin 23 | NC — Not connected |
| Pin 24 | NC — Not connected |
| Pin 25 | NC — Not connected |
| Pin 26 | NC — Not connected |
| Pin 27 | NC — Not connected |
| Pin 28 | NC — Not connected |
Typical Applications
MAX1400EAI is suitable for 6 applications: Industrial Process Control and 4-20 mA Loops, Weigh Scales and Load-Cell Digitization, Portable Battery-Powered Instrumentation, Smart Sensor Transmitters, Medical Patient Monitoring Devices, Temperature Measurement and Thermocouple Digitization.
Industrial Process Control and 4-20 mA Loops
The MAX1400EAI is well suited to industrial process-control signal chains where multiple analog signals must be digitized with high noise immunity. Its 18-bit sigma-delta architecture achieves true 16-bit accuracy at 480 sps, and the integrated PGA (gain 1 to 128) and excitation current sources allow direct connection to RTDs, thermocouples, and bridge sensors without a separate instrumentation amplifier. The 1.7 mA supply current makes it practical for loop-powered 4-20 mA smart transmitters where total power budget is constrained to under 3.5 mA per the HART protocol.
Recommended
Weigh Scales and Load-Cell Digitization
Load cells and weigh scales generate differential output signals in the millivolt range that demand both high gain and high common-mode rejection. The MAX1400EAI's on-chip PGA with gain up to 128 amplifies low-level bridge outputs directly, and the integrated excitation current sources drive the bridge without external circuitry. Combined with the sigma-delta modulator's inherent noise shaping, the part achieves stable, drift-free weight readings that match discrete analog front-end performance at a fraction of the board area and BOM cost.
Recommended
Portable Battery-Powered Instrumentation
Battery-powered handheld instruments require both low operating current and high measurement accuracy. The MAX1400EAI draws only 1.7 mA from a single +5V supply, allowing multi-cell battery designs to operate for thousands of measurements on a single charge. The wide PGA gain range simplifies the analog front end for portable multimeters, data loggers, and field calibration instruments that previously required multiple op-amps and a separate ADC.
Recommended
Smart Sensor Transmitters
Smart sensor transmitters combine sensing, signal conditioning, ADC, and digital communication in a single loop-powered device. The MAX1400EAI integrates the conditioning and conversion stages, leaving only the microcontroller, HART modem, and protection circuits to complete the transmitter. Its SPI-compatible serial interface connects directly to low-cost microcontrollers, and the on-chip calibration registers enable factory calibration to be stored in microcontroller EEPROM for true one-point field recalibration.
Recommended
Medical Patient Monitoring Devices
Medical monitoring devices such as blood-pressure cuffs, infusion pumps, and patient thermometers require high-resolution, low-noise analog conversion in compact, low-power packages. The MAX1400EAI's sigma-delta architecture rejects line-frequency interference (50/60 Hz) directly through its digital filter, eliminating the need for external notch filters in patient-side electronics. The 28-SSOP package fits handheld device enclosures while the integrated PGA simplifies ECG and temperature sensor signal paths.
Recommended
Temperature Measurement and Thermocouple Digitization
Thermocouple and RTD temperature measurements require high-gain amplification and accurate reference handling in noisy industrial environments. The MAX1400EAI's programmable excitation current sources drive RTDs directly while its PGA gains thermocouple outputs to the full-scale input range, and the sigma-delta modulator's inherent integration rejects 50/60 Hz mains pickup. Cold-junction compensation can be performed in software using a separate reference-junction sensor read through one of the auxiliary analog input channels.
Recommended
Recommended Products Summary
Engineering reference data for MAX1400EAI — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX1400EAI+ | MAX1400EAI+T | MAX1400CAI+ | MAX1402EAI+ |
|---|---|---|---|---|---|
| Brand | Analog Devices (formerly Maxim Integrated) | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 28-SSOP | 28-SSOP - same | 28-SSOP - same | 28-SSOP - same | 28-SSOP - same |
Key Differentiators
- Industrial temperature range with integrated PGA (vs MAX1400CAI+)
- RoHS-compliant lead-free finish variant available (vs MAX1400EAI (non-'+'))
- All-in-one front-end: PGA + excitation current sources + sigma-delta ADC (vs MAX1402EAI+)
Design Notes
Power the MAX1400EAI from a clean +5V analog rail. The part has separate AVDD and DVDD pins; decouple each pin with a 10 uF tantalum (or 10 uF ceramic) bulk capacitor plus a 100 nF ceramic bypass capacitor placed within 5 mm of the supply pins. A ferrite bead between AVDD and the digital +5V supply prevents digital switching noise from coupling into the analog modulator and degrading noise performance.
Route analog input traces differentially and keep them away from digital clock and serial interface traces. The sigma-delta modulator samples at high oversampling rates and is sensitive to common-mode noise; use a ground plane under the analog section and stitch vias around the analog input pins to minimize ground impedance. Place the reference bypass capacitor (typically 0.1 uF to 10 uF) directly between REF+ and REF- pins.
When using PGA gains above 32, the absolute input common-mode voltage range is reduced; refer to the manufacturer datasheet input specifications before connecting signals that swing near AVDD or GND. Do not leave the calibration registers at default values for production units - run the on-chip self-calibration after power-up and store the result, as uncorrected offset can exceed several LSB at high PGA gains.
Compliance Information
The MAX1400EAI (without '+' suffix) uses legacy leaded finish and is not RoHS compliant. The MAX1400EAI+ variant is RoHS compliant. This page documents the legacy MAX1400EAI; new designs should choose the MAX1400EAI+.
