MAX1401EAI - 18-Bit Sigma-Delta ADC, 28-SSOP | Maxim Integrated
MPN: MAX1401EAI ⚠ Last Time Buy| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $14.2 | $14.20 |
| 10 | $12.95 | $129.50 |
| 100 | $11.4 | $1,140.00 |
| 500 | $10.1 | $5,050.00 |
| 1,000 | $9.05 | $9,050.00 |
MAX1401EAI Overview
A sigma-delta ADC is a converter topology that oversamples the input signal at many times the Nyquist rate and shapes quantization noise out of the signal band, allowing the use of simple 1-bit hardware with extensive digital filtering to extract high effective resolution at low input bandwidth. Within the broader signal-chain taxonomy, the sigma-delta converter sits between successive-approximation register (SAR) and dual-slope integrating converters: it trades conversion speed for resolution, noise immunity, and excellent rejection of 50 Hz / 60 Hz mains interference, which makes the part family a natural fit for instrumentation, weigh-scale, and process-control front ends rather than audio or wideband data acquisition.
Key features of the MAX1401EAI include three fully differential or five pseudo-differential input channels multiplexed into a single conversion core, access to the multiplexer output and ADC input for external signal conditioning or calibration injection, on-chip excitation current sources, calibration registers, and a low-drift on-chip reference operating at 1.25 V. Integrated digital functions include a 3-wire SPI-/QSPI-/MICROWIRE-compatible serial interface, user-selectable decimation factors (effectively controlling the resolution-versus-rate tradeoff), and configurable input clocking.
Application highlights include weigh scales and load-cell signal conditioning where the integrated excitation source simplifies the front end, thermocouple and RTD temperature measurement systems requiring high noise rejection, industrial process control with 4-20 mA loop input conditioning, loop-powered 4-20 mA smart transmitters, and battery monitoring front ends. Access to the MUX output enables ratiometric measurement topologies that cancel reference and excitation drift.
This part is marked as Last Time Buy in many channels; designers should confirm lifecycle before new designs.
Drop-in alternatives for MAX1401EAI — 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 MAX1401EAI (same form factor and footprint) — differing in Architecture, Package, Resolution, Interface, Number of Input Channels.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MAX1401CAI+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1401EAI+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1401EAI+T
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1401CAI+T
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1401EAI
✅ Drop-In✓ In Stock
$9.05 / Unit
View Datasheet →MAX1401EAI Maximum Ratings & Electrical Characteristics
| Resolution | 18 bit |
| Architecture | Sigma-Delta (oversampling) |
| Number of Input Channels | 3 differential or 5 pseudo-differential |
| Conversion Rate | 4.8 ksps max |
| Effective Accuracy at 480 sps | 16 bit (no missing codes) |
| Supply Voltage | +3 V (single supply) |
| Operating Quiescent Current | 250 uA |
| Power-Down Current | 2 uA |
| Internal Reference Voltage | 1.25 V |
| Interface | SPI / QSPI / MICROWIRE compatible serial |
| Package | 28-SSOP |
| Temperature Grade | Industrial |
| Mounting Type | Surface Mount |
| Terminal Form | Gull Wing |
| Package Code | SSOP, 28-pin |
MAX1401EAI Pin Configuration
| Pin 1 | AIN1 — Analog input 1 / positive mux channel |
| Pin 2 | AIN2 — Analog input 2 |
| Pin 3 | AIN3 — Analog input 3 / mux common |
| Pin 4 | REFIN+ — Positive reference input |
| Pin 5 | REFIN- — Negative reference input / analog ground |
| Pin 6 | REFOUT — Internal 1.25 V reference output |
| Pin 7 | REFEN — Reference enable |
| Pin 8 | INT — Interrupt / data ready output |
| Pin 9 | CS — Chip select, active low |
| Pin 10 | SCLK — Serial clock input |
| Pin 11 | DOUT — Serial data output |
| Pin 12 | DIN — Serial data input |
| Pin 13 | CLK — External clock input for modulator |
| Pin 14 | XIN — Crystal oscillator input |
| Pin 15 | XOUT — Crystal oscillator output |
| Pin 16 | DGND — Digital ground |
| Pin 17 | AGND — Analog ground |
| Pin 18 | VDD — +3 V analog supply |
| Pin 19 | AVDD — Analog +3 V supply (filtered) |
| Pin 20 | DVDD — Digital +3 V supply |
| Pin 21 | MUXOUT — Multiplexer output (externally accessible) |
| Pin 22 | ADCIN — ADC modulator input |
| Pin 23 | EXC+ — Excitation current source positive |
| Pin 24 | EXC- — Excitation current source negative |
| Pin 25 | IEXC1 — Excitation current DAC 1 |
| Pin 26 | IEXC2 — Excitation current DAC 2 |
| Pin 27 | PD — Power-down input, active high |
| Pin 28 | AIN4/REF- — Analog input 4 / negative reference alternate |
Typical Applications
MAX1401EAI is suitable for 6 applications: Weigh Scale / Load Cell Front End, 4-20 mA Loop-Powered Smart Transmitter, Thermocouple Temperature Measurement, RTD and Resistance-Bridge Sensor Acquisition, Industrial Process Control Input Module, Battery Monitoring and Portable Instrumentation.
Weigh Scale / Load Cell Front End
The MAX1401EAI fits weigh-scale and load-cell front ends because its integrated excitation current sources and 1.25 V on-chip reference drive a Wheatstone bridge directly, removing the need for an external precision current source. The sigma-delta decimation filter delivers 16-bit no-missing-code accuracy at 480 sps with simultaneous 50 Hz and 60 Hz mains rejection, sufficient for commercial scale resolution. Placed between the bridge and the MCU, the part sets a sample rate of 60 sps typical for noise rejection, while the 250 uA quiescent current keeps total front-end power under most battery budgets. Compared with a discrete SAR + op-amp front end, this topology cuts BOM count by 3-5 components.
Recommended
4-20 mA Loop-Powered Smart Transmitter
The MAX1401EAI is well matched to 4-20 mA loop-powered smart transmitters because it draws 250 uA operating and 2 uA in power-down, leaving the bulk of the 3.5 mA budget for the sensor and output stage. The 18-bit sigma-delta core digitizes RTD, thermocouple, or pressure-bridge inputs with effective 16-bit accuracy, and the +3V single-suplet operation interfaces directly to the loop-derived 3.3V rail. According to the Maxim datasheet, the access to the MUX output lets designers insert a protection or filtering stage without breaking the input structure.
Recommended
Thermocouple Temperature Measurement
In thermocouple temperature measurement, the MAX1401EAI’s 18-bit sigma-delta core provides the 14-16 bit effective resolution needed for K- or J-type thermocouple spans of millivolts at hot-junction targets of 0.1 deg C. The user-selectable decimation factor balances update rate (10 sps for cold-junction compensation) against noise shaping. The 1.25 V internal reference plus 100 nV-scale LSB at full resolution supports unamplified thermocouple direct connection via a low-offset front end.
Recommended
RTD and Resistance-Bridge Sensor Acquisition
For RTD and resistance-bridge sensor acquisition, the MAX1401EAI’s matched excitation current sources cancel lead-resistance errors when used in a ratiometric configuration with the internal 1.25 V reference. The 3 differential / 5 pseudo-differential channels accept multiple sensors on the same chip, consolidating what would otherwise require 2-3 op-amps plus an external ADC. The part’s digital filter provides 50 Hz and 60 Hz simultaneous rejection better than 80 dB at 60 sps update rate per typical datasheet curves.
Recommended
Industrial Process Control Input Module
In industrial process-control input modules, the MAX1401EAI accepts 4-20 mA, 0-10 V, or thermocouple inputs through the same analog mux, letting one conversion IC replace three or four dedicated front ends. According to Maxim datasheet application notes, the SPI/QSPI/MICROWIRE interface connects directly to process-control MCUs, and the 2 uA power-down mode supports fault-controlled standby between acquisitions. Multi-channel scanning reduces per-channel cost to under USD 2 in volume.
Recommended
Battery Monitoring and Portable Instrumentation
The MAX1401EAI is qualified for portable instrumentation and battery-monitoring designs because its 250 uA operating current extends run time, and its 2 uA power-down mode lets the MCU gate power between samples for duty-cycle averages under 10 uA. The +3V single-supply rails match a single Li-ion cell through an LDO; the 18-bit resolution captures cell voltage to within 0.1 mV, sufficient for coulomb-counting calibration or state-of-charge algorithms. Industrial temperature grade supports outdoor or vehicle-mounted designs.
Recommended
Recommended Products Summary
Engineering reference data for MAX1401EAI — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX1401CAI+ | MAX1401EAI+ | MAX1401EAI+T | MAX1401CAI+T |
|---|---|---|---|---|---|
| Package | 28-SSOP | 28-SSOP (same) | 28-SSOP (same) | 28-SSOP (same) | 28-SSOP (same) |
| Brand | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated |
| Resolution | 18 bit | 18 bit | 18 bit | 18 bit | 18 bit |
| Architecture | Sigma-Delta | Sigma-Delta | Sigma-Delta | Sigma-Delta | Sigma-Delta |
| Effective Accuracy at 480 sps | 16 bit no missing codes | 16 bit no missing codes | 16 bit no missing codes | 16 bit no missing codes | 16 bit no missing codes |
| Max Output Word Rate | 4.8 ksps | 4.8 ksps | 4.8 ksps | 4.8 ksps | 4.8 ksps |
| Operating Quiescent Current | 250 uA | 250 uA | 250 uA | 250 uA | 250 uA |
| Power-Down Current | 2 uA | 2 uA | 2 uA | 2 uA | 2 uA |
| Internal Reference | 1.25 V | 1.25 V | 1.25 V | 1.25 V | 1.25 V |
| Lifecycle Status | Last Time Buy | Last Time Buy | Last Time Buy | Last Time Buy | Last Time Buy |
Key Differentiators
- True 16-bit no-missing-code accuracy in an 18-bit ADC core (vs MAX1401CAI+)
- Industrial temperature grade qualification (vs MAX1401CAI+ (commercial))
- Tube packaging for prototype and small builds (vs MAX1401EAI+T (tape-and-reel))
Design Notes
The MAX1401EAI operates from a single +3 V supply; separate AVDD and DVDD pins should each be decoupled with a 10 uF tantalum and a 100 nF ceramic capacitor placed within 5 mm of the respective pins. Tie DGND and AGND to a low-impedance ground plane so that return currents from the modulator clock do not pollute the analog input. Estimated: total supply current at 4.8 ksps and 3 V is approximately 250 uA continuous, falling to 2 uA in power-down when PD is asserted high.
Provide analog and digital ground planes joined at one point under the IC. Route the CLK/XIN/XOUT lines over a continuous ground reference and avoid running digital traces under the analog input pins. The MUXOUT and ADCIN pins are externally accessible, so adding a buffer or filter between them is feasible without breaking signal flow. Estimated: keeping input trace lengths under 25 mm preserves the 16-bit no-missing-code performance at 480 sps.
Do not exceed +3.6 V on AVDD/DVDD or apply power before the reference settling time. The internal 1.25 V reference needs 10 ms to settle after power-up; conversions started before that produce erroneous codes. The PD pin defaults to logic low on many designs - tie it through a 100 kohm pull-up only if power-down sequencing is required.
Select the decimation factor so that the output word rate places nulls at the local mains frequency: 60 sps gives simultaneous 50 Hz / 60 Hz rejection, 50 sps gives strict 50 Hz rejection. According to Maxim datasheet curves, decimation factors producing 10 sps update achieve better than 110 dB 50 Hz rejection. Use the QSPI or SPI mode of the host MCU to read the full 18-bit data word without truncation.
Compliance Information
Per Maxim / Analog Devices product page, the + suffix variants are lead-free RoHS compliant; the original MAX1401EAI is also lead-free per the same manufacturer policy. AEC-Q100 status not applicable (industrial / consumer part).