MAX1271AENG - 12-Bit 8-Ch 110ksps Multirange ADC | Maxim
MPN: MAX1271AENG ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $12.5 | $12.50 |
| 10 | $11.25 | $112.50 |
| 100 | $9.95 | $995.00 |
| 500 | $8.75 | $4,375.00 |
| 1,000 | $7.95 | $7,950.00 |
MAX1271AENG Overview
An ADC (analog-to-digital converter) is a mixed-signal integrated circuit that samples a continuous analog input voltage and converts it into a discrete digital code for use by a microcontroller or DSP. The MAX1271AENG belongs to the SAR ADC product family, which is favored in multiplexed multi-channel data acquisition because SAR converters offer deterministic latency, easy channel-to-channel synchronization, and require no settling-time programming between conversions. Within the broader taxonomy, a SAR ADC sits under precision ADC, which sits under data converter (ADC/DAC), which is a subcategory of mixed-signal ICs and ultimately of integrated circuits.
Key features of the MAX1271AENG include a three-wire SPI/QSPI/MICROWIRE-compatible serial interface, hardware- or software-controlled shutdown that drops supply current below 10 uA between conversions, an internal 4.096V reference (or optional external reference up to +4.096V for ratio-metric conversions), and four bipolar analog input ranges. The 24-pin PDIP package simplifies prototyping on through-hole breadboards and is well suited to industrial process-control, instrumentation, and front-end signal conditioning.
The internal architecture combines an 8-channel analog multiplexer, a track-and-hold amplifier with a 200 ns acquisition time, the SAR core, and the digital serial interface. The reference buffer can drive the external reference pin as a low-impedance source, improving settling when switching between multiplexed channels with widely differing amplitudes.
Typical applications include multi-channel sensor data acquisition systems (RTDs, thermocouples, and 4-20 mA loop transmitters), industrial process controls, weigh scales, panel meters, and general-purpose 12-bit instrumentation. The wide input ranges make the part particularly attractive in systems where bipolar signals or signals up to +/-15V must be digitized without active front-end signal conditioning.
When designing with the MAX1271AENG, provide a 0.1 uF ceramic bypass capacitor within 5 mm of VDD and a low-ESR bulk capacitor on the analog supply to preserve the converter's 12-bit noise performance across the 0-110 ksps throughput range.
This page synthesizes distributor pricing, drop-in alternative parts, and practical design notes for the MAX1271AENG that are not found in the manufacturer datasheet alone.
Drop-in alternatives for MAX1271AENG — 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 MAX1271AENG (same form factor and footprint) — differing in Input Voltage Range, Number of Channels, Package, Supply Voltage, Resolution.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MAX1271AENG+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1271BCNG
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1271BENG
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1270AENG+
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1270BENG
✅ Drop-In✓ In Stock
$19.85 / Unit
View Datasheet →MAX120ENG
✅ Drop-In📋 Reference alternative (not in catalog)
MAX1271AENG Maximum Ratings & Electrical Characteristics
| Resolution | 12 bits |
| Number of Channels | 8 |
| Sampling Rate | 110 ksps |
| Supply Voltage | +5 V (single supply) |
| Input Voltage Range | 0 to VREF, 0 to 2xVREF, 0 to 4xVREF, +/-VREF (4 software-selectable) |
| Integral Nonlinearity (INL) | +/-0.5 LSB (max) |
| Reference Voltage | +4.096 V internal (or external) |
| Interface | 3-wire SPI/QSPI/MICROWIRE-compatible serial |
| Architecture | SAR (Successive Approximation) |
| Shutdown Current | < 10 uA |
| Acquisition Time | 200 ns (typical) |
| Package | 24-pin PDIP (DIP-24, 0.300 inch) |
| Mounting Type | Through-Hole |
| Operating Temperature | -40 C to +85 C (extended-industrial grade per datasheet) |
MAX1271AENG Pin Configuration
| Pin 1 | VDD — +5V analog supply |
| Pin 2 | AGND — Analog ground |
| Pin 3 | REF — Reference input / internal 4.096V reference bypass |
| Pin 4 | AIN1 — Analog input channel 1 |
| Pin 5 | AIN2 — Analog input channel 2 |
| Pin 6 | AIN3 — Analog input channel 3 |
| Pin 7 | AIN4 — Analog input channel 4 |
| Pin 8 | AIN5 — Analog input channel 5 |
| Pin 9 | AIN6 — Analog input channel 6 |
| Pin 10 | AIN7 — Analog input channel 7 |
| Pin 11 | AIN8 — Analog input channel 8 |
| Pin 12 | SHDN — Hardware shutdown (active low) - puts ADC in < 10 uA sleep |
| Pin 13 | CS — Chip select for 3-wire serial interface (active low) |
| Pin 14 | DIN — Serial data input |
| Pin 15 | SCLK — Serial clock input |
| Pin 16 | DOUT — Serial data output |
| Pin 17 | DGND — Digital ground |
| Pin 18 | REFADJ — Reference adjust (use with external buffer) |
| Pin 19 | INT — [DATA_NEEDED - per-pin function depends on datasheet pinout table; verify against manufacturer pinout] |
| Pin 20 | NC — Not connected (per datasheet) |
| Pin 21 | NC — Not connected (per datasheet) |
| Pin 22 | NC — Not connected (per datasheet) |
| Pin 23 | NC — Not connected (per datasheet) |
| Pin 24 | NC — Not connected (per datasheet) |
Typical Applications
MAX1271AENG is suitable for 6 applications: Multi-Channel Industrial Process Control, Data Acquisition Systems (DAQ) for Sensor Panels, Panel Meters and Weigh Scales, Battery-Powered Portable Instrumentation, Medical Patient Monitoring Front Ends, General-Purpose 12-Bit Instrumentation.
Multi-Channel Industrial Process Control
The MAX1271AENG is well suited to multi-channel industrial process-control front ends because it integrates an 8-channel analog multiplexer behind a single 12-bit SAR core, eliminating external signal-switching hardware. Its software-selectable input ranges (0-VREF, 0-2xVREF, 0-4xVREF, +/-VREF) let a single ADC digitize 4-20 mA loop transmitters, thermocouple outputs (after cold-junction compensation), and 0-10 V actuator signals without front-end scaling amplifiers. With 110 ksps aggregate throughput and an acquisition time of 200 ns, the part can scan 8 channels in under a millisecond, well within the loop time of typical PID loops. Power dissipation stays low because the 5V single supply keeps the part quiescent current low, and the shutdown mode (< 10 uA) lets unused channels be gated off between scans.
Recommended
Data Acquisition Systems (DAQ) for Sensor Panels
In multi-sensor data acquisition systems, the MAX1271AENG shines because of its 8 single-ended inputs, internal 4.096V reference, and SPI-compatible serial output that interfaces cleanly with MCUs and DSPs. Each of the eight inputs can read a different physical quantity - strain gauge, RTD bridge, thermistor divider, or potentiometer wiper - while the SAR architecture ensures deterministic conversion latency, a property that simplifies time-aligned logging. The 4 software-selectable input ranges accommodate sensors with widely varying full-scale outputs, from milli-volt bridges to 0-10 V actuator feedback, without external op-amp conditioning. The MAX1271AENG's 24-pin PDIP package simplifies hand-soldered prototyping and rework in lab/bench DAQ systems.
Recommended
Panel Meters and Weigh Scales
Panel meters and weigh scales benefit from the MAX1271AENG's combination of 12-bit resolution, internal voltage reference, and bipolar input range. Load-cell bridges typically produce millivolt-level differential signals that the MAX1271AENG can digitize directly using the +/-VREF range with an external reference, or by attenuating higher-level signals to the 0-VREF range via simple resistor dividers. The low integral nonlinearity of +/-0.5 LSB ensures stable readings across the scale's operating temperature, while the shutdown mode dropping supply current below 10 uA enables battery-powered handheld meters to extend runtime between charges. The 24-pin PDIP through-hole package is also an advantage for service-replaceable modules in field-deployed weigh scales.
Recommended
Battery-Powered Portable Instrumentation
Battery-powered portable instruments benefit from the MAX1271AENG's < 10 uA hardware-shutdown current between scans - the ADC wakes, samples, and returns to sleep on every conversion, preserving battery lifetime over months of standby. Because the part operates from a single +5V rail, it pairs naturally with USB-powered or 4xAA battery instruments, and the 24-pin PDIP is forgiving for hand-rework in field upgrades. The internal +4.096V reference eliminates a separate reference IC on the BOM. With an 8-channel multiplexer built in, one MAX1271AENG replaces multiple external mux chips and discrete amplifier channels, shrinking the bill of materials for portable loggers, environmental monitors, and medical telemetry devices where multi-physical-channel readout at low standby power is essential.
Recommended
Medical Patient Monitoring Front Ends
In medical patient monitoring, the MAX1271AENG is attractive because it integrates eight analog input channels behind a single SAR ADC with deterministic latency and a 12-bit resolution adequate for many front-end signal-conditioning blocks. Combined with external instrumentation amplifiers, the part can digitize ECG leads, SpO2 photodiode currents (after transimpedance amplification), respiration impedance signals, and temperature sensor bridges with synchronized timing. The wide 0-4xVREF input range allows direct connection to amplified biopotential signals without further scaling. The shutdown mode and small PDIP footprint suit bedside-monitor signal boards where board area and standby power are tightly constrained.
Recommended
General-Purpose 12-Bit Instrumentation
The MAX1271AENG is well suited to general-purpose instrumentation where a designer needs a flexible, easy-to-interface 12-bit ADC with multiple input ranges. Laboratory measurement tools, bench multimeter front ends, and educational lab boards benefit from the 8-channel mux and software-selectable input ranges, allowing a single ADC to handle millivolt and tens-of-volt signals alike. The MAX1271's 3-wire SPI/QSPI/MICROWIRE-compatible interface drops cleanly into MCU-based learning kits and Arduino-class platforms through simple GPIO bit-banging. Because the part is widely documented in Maxim/Analog Devices reference designs and is supported by an evaluation kit (MAX1270 EV kit), engineers can prototype quickly without building a custom ADC interface from scratch.
Recommended
Recommended Products Summary
Engineering reference data for MAX1271AENG — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MAX1271AENG+ | MAX1271BCNG | MAX1271BENG | MAX1270AENG+ | MAX1270BENG | MAX120ENG |
|---|---|---|---|---|---|---|---|
| Brand | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated |
| Package | PDIP-24 (DIP-24, 0.300 in) | PDIP-24 (DIP-24, 0.300 in) | PDIP-24 (DIP-24, 0.300 in) | PDIP-24 (DIP-24, 0.300 in) | PDIP-24 (DIP-24, 0.300 in) | PDIP-24 (DIP-24, 0.300 in) | PDIP-24 (DIP-24, 0.300 in) |
| Resolution | 12 bits | 12 bits | 12 bits | 12 bits | 12 bits | 12 bits | 12 bits |
| Number of Channels | 8 | 8 | 8 | 8 | 8 | 8 | 1 (single channel, bipolar) |
| Interface | 3-wire SPI/QSPI/MICROWIRE | 3-wire SPI/QSPI/MICROWIRE | 3-wire SPI/QSPI/MICROWIRE | 3-wire SPI/QSPI/MICROWIRE | 3-wire SPI/QSPI/MICROWIRE | 3-wire SPI/QSPI/MICROWIRE | 3-wire SPI |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete (per Avaq comparison) | Obsolete | Obsolete |
Key Differentiators
- Eight single-ended analog channels behind one SAR ADC (vs MAX120ENG)
- Four software-selectable input ranges including 0-4xVREF and bipolar (vs MAX1270AENG+)
- Same package footprint across the MAX1271 family (Pb-free vs leaded, B-grade vs A-grade) (vs MAX1271BCNG)
Design Notes
Place a 0.1 uF ceramic bypass capacitor within 5 mm of the VDD pin and a 2.2-10 uF low-ESR bulk capacitor on the analog supply. The MAX1271AENG's internal 4.096V reference is sensitive to high-frequency supply noise - insufficient decoupling directly degrades 12-bit noise performance and degrades last-code stability. Use a separate analog ground pour tied to AGND (pin 2), not to the digital ground return, to avoid ground-loop coupling into the analog input network.
When muxing between channels with widely different amplitudes (e.g. thermocouple mV vs 0-10V actuator feedback), insert at least 2 acquisition-time slots before the conversion to allow the internal track-and-hold to settle. The MAX1271's 200 ns acquisition time is rated for full-scale transitions, but high-impedance sensors (>5 kohm source impedance) require an external input buffer (e.g. a MAX400 op-amp follower) to avoid acquisition-time errors that show up as 1-2 LSB gain error.
Do not apply input voltages outside the selected input range or above the Absolute Maximum ratings of VDD + 0.3V; the input multiplexer ESD diodes clamp excessive voltages and forward-bias into VDD, which can couple noise into the supply. Always tie unused analog inputs (AINx) to AGND, not to GND, to avoid noise injection into the multiplexer. Confirm the SHDN pin is held high (logic 1) during normal operation; leaving SHDN floating can cause intermittent shutdown.
Compliance Information
Compliance status could not be extracted from the verified search results. The MAX1271AENG+ (with '+' suffix per Maxim nomenclature) is generally understood to be Pb-free and lead-free; the base MAX1271AENG without '+' suffix likely uses a leaded finish - confirm with the manufacturer for any new design.
