MAX1231ACEG+ - 12-Bit 300ksps 16-Ch SAR ADC | Maxim Integrated
MPN: MAX1231ACEG+ ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $9.95 | $9.95 |
| 10 | $8.96 | $89.60 |
| 100 | $7.96 | $796.00 |
| 500 | $7.16 | $3,580.00 |
| 1,000 | $6.37 | $6,370.00 |
MAX1231ACEG+ Overview
An SAR ADC is a type of data converter that uses a binary-search successive-approximation algorithm to digitize an analog input voltage within one conversion cycle. The MAX1231 belongs to the data-acquisition IC family, which itself sits in the broader analog-to-digital converter hierarchy under signal chain and data conversion. SAR ADCs are favored over delta-sigma converters in multiplexed applications because they offer low latency, deterministic throughput, and excellent DC accuracy without the digital filtering delay of oversampling architectures.
Key features of the MAX1231ACEG+ include an internal FIFO that allows up to 16 conversion results to be stored before servicing interrupts, an internal temperature sensor that returns die temperature with 1°C accuracy, an internal 2.5V reference (with optional external reference override), single-ended or pseudo-differential input modes, and a high-speed SPI/QSPI/MICROWIRE-compatible serial interface. The device supports software-configurable analog inputs (8 single-ended or 16 inputs in scan mode) and provides programmable scan averaging (1, 2, 4, 8, 16, 32, 64, or 128 samples).
Architecturally, the MAX1231 uses a capacitive charge-redistribution DAC and an input track-and-hold, which gives true 12-bit linearity (INL and DNL both below ±1 LSB max) and low aperture delay. An integrated input-protection clamp allows the inputs to tolerate ±6V fault voltages without latch-up, simplifying connection to industrial sensor networks where transients are common. The internal reference and FIFO reduce host-side overhead, allowing a low-cost microcontroller to manage up to 16 analog channels with minimal bus traffic.
Typical applications for the MAX1231ACEG+ include industrial process control and monitoring, multichannel data-acquisition systems, temperature-compensated sensor front ends, HVAC controls, battery-cell monitoring, and rack-mounted instrumentation. The wide analog input range, internal reference, and integrated temperature channel are particularly useful in distributed I/O modules.
When designing with this ADC, ensure adequate decoupling on both AVDD and DVDD pins (typically a 10 µF bulk plus a 0.1 µF ceramic) and place the bypass capacitor on the REF pin within 5 mm of the REF pin to preserve reference stability. The serial-interface clock can run up to 10 MHz in SPI mode 0, but the 300 ksps throughput ceiling must be respected by timing the SCLK bursts accordingly.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, including a pinout reference and parametric comparison against same-family Maxim and Analog Devices 12-bit ADC options.
Drop-in alternatives for MAX1231ACEG+ — 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 MAX1231ACEG+ (same form factor and footprint) — differing in External Reference Range, Number of Input Channels, Operating Temperature Range, Package.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MAX1231BCEG+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1229ACEG+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1227ACEG+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1231ACEG+T
✅ Drop-In✓ In Stock
$4.65 / Unit
View Datasheet →MAX1068BCEG+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1231ACEG+ Maximum Ratings & Electrical Characteristics
| Resolution | 12 bit |
| Sample Rate | 300 ksps |
| Number of Input Channels | 8 / 16 (selectable) |
| Input Configuration | Single-ended / pseudo-differential |
| Conversion Architecture | SAR (Successive Approximation) |
| Analog Supply Voltage (AVDD) | 3.0 V to 3.6 V |
| Digital Supply Voltage (DVDD) | 2.7 V to VAVDD |
| Internal Reference | 2.5 V |
| External Reference Range | 1.0 V to AVDD |
| Integral Nonlinearity (INL) | ±1 LSB (max) |
| Differential Nonlinearity (DNL) | ±1 LSB (max, no missing codes) |
| Internal FIFO Depth | 16 conversions |
| Internal Temperature Sensor | Yes (±1 °C typical accuracy) |
| Serial Interface | SPI / QSPI / MICROWIRE-compatible |
| Maximum SCLK Frequency | 10 MHz |
| Input Fault Tolerance | ±6 V (clamped, no latch-up) |
| Package | 24-QSOP (EG) |
| Operating Temperature Range | 0 °C to +70 °C (commercial, C grade) |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
MAX1231ACEG+ Pin Configuration
| Pin 1 | AIN0/AIN0+ — Analog input channel 0 (single-ended or pseudo-differential +) |
| Pin 2 | AIN1/AIN0- — Analog input channel 1 (single-ended or pseudo-differential -) |
| Pin 3 | AIN2 — Analog input channel 2 |
| Pin 4 | AIN3 — Analog input channel 3 |
| Pin 5 | AIN4 — Analog input channel 4 |
| Pin 6 | AIN5 — Analog input channel 5 |
| Pin 7 | AIN6 — Analog input channel 6 |
| Pin 8 | AIN7 — Analog input channel 7 |
| Pin 9 | AIN8 — Analog input channel 8 |
| Pin 10 | AIN9 — Analog input channel 9 |
| Pin 11 | AIN10 — Analog input channel 10 |
| Pin 12 | AIN11 — Analog input channel 11 |
| Pin 13 | AIN12 — Analog input channel 12 |
| Pin 14 | AIN13 — Analog input channel 13 |
| Pin 15 | AIN14 — Analog input channel 14 |
| Pin 16 | AIN15 — Analog input channel 15 |
| Pin 17 | REF — Reference input/output (internal 2.5 V or external 1.0 V to AVDD) |
| Pin 18 | AVDD — Analog supply voltage (3.0 V to 3.6 V) |
| Pin 19 | AGND — Analog ground |
| Pin 20 | DGND — Digital ground |
| Pin 21 | DVDD — Digital supply voltage (2.7 V to VAVDD) |
| Pin 22 | CS — Active-low chip-select input |
| Pin 23 | SCLK — Serial-clock input (up to 10 MHz) |
| Pin 24 | DOUT — Serial-data output (SPI/QSPI/MICROWIRE) |
Typical Applications
MAX1231ACEG+ is suitable for 6 applications: Industrial Process Control & Monitoring, Multichannel Data-Acquisition Systems, HVAC & Building Automation, Battery-Cell Monitoring & Management, Portable & Handheld Instrumentation, Sensor-Conditioning Front Ends.
Industrial Process Control & Monitoring
The MAX1231ACEG+ is well suited for industrial process-control front ends, where multiple analog channels must be sampled at low latency with high DC accuracy. Its 16-channel input multiplexer covers thermocouples, 4-20 mA loop receivers, and bridge sensors through signal conditioning, while the SAR architecture eliminates the digital-filter delay of delta-sigma converters, giving deterministic per-channel latency. The ±6 V input fault tolerance protects the inputs from industrial transients on long cable runs, and the internal 2.5 V reference removes the need for a separate external reference. Engineers can run scan-mode conversion at 300 ksps aggregate throughput and use the 16-deep FIFO to batch results before host interrupts, freeing the microcontroller for control-loop math.
Recommended
Multichannel Data-Acquisition Systems
For rack-mounted and distributed data-acquisition systems, the MAX1231ACEG+ offers 16 inputs at 12-bit 300 ksps in a compact 24-QSOP footprint, enabling high channel density per square inch of PCB. The internal FIFO of 16 results lets the host read multiple conversions in a single SPI burst, reducing bus overhead and lowering interrupt rates. The internal temperature sensor gives system designers a free health-monitoring channel for board-temperature telemetry. With AVDD = 3.3 V and DVDD = 2.7-3.6 V, the part interfaces cleanly with most 3.3 V microcontrollers and DSPs, and the SPI/QSPI/MICROWIRE-compatible interface supports data rates up to 10 MHz on SCLK.
Recommended
HVAC & Building Automation
HVAC controllers routinely digitize temperature, humidity, pressure, and flow-sensor outputs. The MAX1231ACEG+ integrates 16 single-ended inputs and an on-die temperature sensor, replacing multiple thermistor-reading amplifiers with one ADC. Its low conversion latency supports closed-loop fan-speed and damper-position control, where each loop cycle must complete within milliseconds. The internal 2.5 V reference and FIFO allow the HVAC controller to be built with fewer external parts, reducing BOM cost. The part's commercial 0-70 °C operating range covers indoor environments, and the QSOP-24 footprint suits small control-panel enclosures.
Recommended
Battery-Cell Monitoring & Management
In battery-management systems, multiple cell voltages, current-sense amplifier outputs, and temperature sensors must be sampled synchronously or near-synchronously. The MAX1231ACEG+ offers 16 inputs at 300 ksps with scan-mode averaging (up to 128 samples), allowing accurate cell-voltage measurement under high-noise inverter environments. The pseudo-differential input mode improves common-mode rejection of ground bounce in stacked-cell packs, and the 16-deep FIFO batches results to reduce host-side interrupt load. With ±6 V input fault tolerance, the ADC tolerates transients during plug/unplug events, protecting the measurement chain.
Recommended
Portable & Handheld Instrumentation
Handheld test instruments benefit from the MAX1231ACEG+'s compact 24-QSOP package, low supply current, and integrated temperature sensor. The 300 ksps throughput allows digital multimeters and logic analyzers to capture waveforms at high sample rates while keeping BOM cost low. The internal 2.5 V reference reduces external components, while the SPI interface simplifies connection to ARM Cortex-M or MSP430 microcontrollers commonly used in portable designs. The 3.0-3.6 V AVDD range aligns directly with single-cell Li-ion or 3.3 V system rails.
Recommended
Sensor-Conditioning Front Ends
The MAX1231ACEG+ can directly digitize strain-gauge, load-cell, RTD, and thermocouple outputs through simple external signal conditioning. Its 12-bit resolution and ±1 LSB linearity give 0.024% full-scale accuracy, sufficient for industrial weighing and pressure-monitoring applications. The internal FIFO buffers up to 16 conversions, allowing host averaging to suppress 50/60 Hz line noise before threshold detection. The integrated temperature sensor enables cold-junction compensation for thermocouple measurements in the same IC, eliminating the need for a separate thermistor ADC channel.
Recommended
Recommended Products Summary
Engineering reference data for MAX1231ACEG+ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX1231BCEG+ | MAX1229ACEG+ | MAX1227ACEG+ | MAX1068BCEG+ |
|---|---|---|---|---|---|
| Brand | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated |
| Package | 24-QSOP (EG) | 24-QSOP (EG) - same | 24-QSOP (EG) - same | 24-QSOP (EG) - same | 24-QSOP (EG) - same |
| Resolution | 12 bit | 12 bit | 12 bit | 12 bit | 14 bit |
| Sample Rate | 300 ksps | 300 ksps | 225 ksps | 225 ksps | 200 ksps |
| Input Channels | 8 / 16 | 8 / 16 | 8 / 12 | 8 / 12 | 4 / 8 |
| Internal Reference | 2.5 V | 2.5 V | 2.5 V | 2.5 V | 2.5 V |
| Internal FIFO | 16 conversions | 16 conversions | 16 conversions | 16 conversions | 8 conversions |
| Internal Temperature Sensor | Yes | Yes | Yes | Yes | No |
| Operating Temperature Range | 0 °C to +70 °C | 0 °C to +70 °C | 0 °C to +70 °C | 0 °C to +70 °C | 0 °C to +70 °C |
Key Differentiators
- Highest channel count in the QSOP-24 family (vs MAX1229ACEG+)
- Higher resolution at moderate sample rate (vs MAX1068BCEG+)
- Tighter linearity grade option available (vs MAX1231BCEG+)
Design Notes
Decouple both AVDD and DVDD with a 10 µF bulk capacitor in parallel with a 0.1 µF ceramic capacitor placed within 5 mm of each supply pin. According to the datasheet, DVDD may be driven from a separate 2.7 V to VAVDD rail for logic-level shifting, or tied directly to AVDD for single-3.3 V operation. In noisy industrial environments, add a ferrite bead between AVDD and the upstream LDO to suppress switching-conductor ripple.
Keep analog and digital ground returns separated until they tie together at the ADC's AGND/DGND pins to avoid digital switching noise coupling into the analog input multiplexer. Place the REF-pin bypass capacitor (typically 0.1 µF ceramic) within 5 mm of the REF pin; the internal reference stability depends on this capacitor. Route analog input traces as short as possible, and guard them with ground traces to reduce crosstalk between channels.
For best SINAD performance, drive each analog input through a low-impedance source (≤ 1 kΩ). High source resistance degrades AC performance due to the ADC's input sampling transients; adding an external input buffer op-amp is recommended for source impedances above 5 kΩ. When using the pseudo-differential input mode, keep the common-mode voltage within the AVDD/2 ±0.1 V window for full 12-bit linearity. Avoid routing analog traces parallel to the SCLK or DOUT traces to minimize digital coupling.
Do not exceed the absolute maximum analog input voltage of AVDD + 0.3 V or below AGND - 0.3 V (without the ±6 V fault clamp). Although the internal clamps tolerate ±6 V transients, sustained overvoltage can degrade linearity. Do not leave the CS pin floating - tie it high to DVDD through a 100 kΩ pull-up to avoid spurious conversion triggers. Ensure the FIFO is flushed before changing scan-mode configuration, otherwise stale data may be misread on the next acquisition cycle.
Compliance Information
RoHS-compliant per Maxim Integrated product page. Not AEC-Q100 qualified (automotive grade 'E' variants exist but this is the commercial 'C' grade). Operating temperature 0 °C to +70 °C.
