Analog Devices Inc./Maxim Integrated MAX1270AENG

Overview

The MAX1270AENG from Maxim Integrated is a multirange, +5V-supply, 8-channel, serial 12-bit analog-to-digital converter (ADC) with ±16.5V overvoltage-tolerant inputs, software-selectable input ranges (±10V, ±5V, 0 to +10V, 0 to +5V), and SPI/QSPI/MICROWIRE-compatible 3-wire interface. It delivers 110ksps throughput, 0.5 LSB integral nonlinearity, and fault protection across all channels - enabling direct interfacing of industrial 4–20mA and ±12V/±15V sensors in single-supply data-acquisition systems.

For engineers reviewing the MAX1270AENG datasheet, MAX1270AENG pinout, MAX1270AENG application, or MAX1270AENG equivalent, this page provides verified technical context, validated pin functions, confirmed multirange ADC operation under ±10V bipolar and 0 to +10V unipolar modes, real-world power-down behavior (STBYPD/FULLPD), and precise timing constraints for external clock mode at 1.8MHz.

Technical Context

The MAX1270AENG implements a successive-approximation register (SAR) architecture with integrated track/hold, supporting both internal and external clocking. Its analog front-end uses a resistor-divider network (R1=12.5kΩ, R2=8.67kΩ) to scale inputs per selected range, with channel input resistance varying by mode: <4Ω effective source impedance required for minimal gain error in bipolar/±10V mode.

Conversion timing is strictly defined: acquisition requires six clock cycles (3.3µs min at fCLK=1.8MHz), followed by 12-bit SAR decision cycle; total conversion time is 6.6µs in external clock mode. The device supports two power-down states - STBYPD maintains reference buffer bias for fast wake-up, while FULLPD reduces supply current to 120–220µA.

Key Specifications

Pinout & Package

MAX1270AENG is packaged in a 24-pin narrow plastic DIP (PDIP) with 0.3-inch body width, RoHS-compliant lead finish, and standard through-hole mounting. Pin 1 is VDD; pins 2 and 4 are DGND; pins 13–20 are analog input channels CH0–CH7; pin 11 is SHDN; pin 23 is REF; pin 21 is REFADJ.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multirange, serial 12-bit ADC applications.

Compared with MAX1270AENG, ADS8320IDR trades configurability for resolution and MAX11607EEE+ sacrifices range flexibility for lower price - neither matches the MAX1270AENG's unique combination of per-channel ±10V/0–10V/±5V/0–5V selection, integrated 4.096V reference, and ±16.5V fault protection in a single +5V supply ADC.

Availability

MAX1270AENG is available at Aetrix Electronics and suitable for industrial process monitoring, automated test equipment, and battery-powered data loggers requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for MAX1270AENG includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated (now part of Analog Devices) is a U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power-management ICs for industrial, medical, and communications applications.

The MAX1270/MAX1271 product line was designed specifically for rugged, single-supply data-acquisition systems needing multirange sensor interfacing, fault tolerance, and SPI-compatible serial control - targeting PLCs, portable instruments, and test equipment where reliability and design simplicity are critical.

FAQ

What input voltage ranges does the MAX1270AENG support per channel?

The MAX1270AENG supports four software-selectable input ranges per analog channel: ±10V, ±5V, 0 to +10V, and 0 to +5V. These are configured independently via the RNG and BIP bits in the 8-bit control byte. The ±10V range corresponds to VREF × 2.4414 (with internal 4.096V reference), enabling direct connection to industrial ±10V sensors without external amplification. Each range maintains 12-bit resolution and ≤±0.5 LSB INL performance.

How does the MAX1270AENG handle overvoltage conditions on its analog inputs?

The MAX1270AENG provides ±16.5V overvoltage tolerance on all eight analog input channels (CH0–CH7) relative to AGND. This protection remains fully active even during FULLPD power-down mode or when VDD = 0. Internal resistor networks limit input current to <2mA during fault events, preventing damage to the internal multiplexer or track/hold circuitry. A fault on any channel does not affect conversion results on other channels, ensuring system robustness in harsh industrial environments.

What are the power-down modes available on the MAX1270AENG and how do they differ?

The MAX1270AENG offers two software-programmable power-down modes: STBYPD (standby) and FULLPD (full power-down). In STBYPD, the reference buffer remains active (IDD ≈ 700–850µA), allowing rapid wake-up (<10µs) with no reference settling delay. In FULLPD, all circuitry except SHDN detection is disabled (IDD = 120–220µA), maximizing battery life but requiring reference buffer re-stabilization (~60ms with 33µF CREF) upon exit. Both modes are selected via PD1/PD0 bits in the control byte.

Can the MAX1270AENG use an external reference, and how is it connected?

Yes, the MAX1270AENG supports external reference operation. To disable the internal 4.096V reference buffer, REFADJ must be pulled to VDD, and the external reference voltage (2.40V to 4.18V) is applied directly to the REF pin. The device accepts references with load regulation <10mV over 0–0.5mA output current. When using external reference, gain error is ±3 LSB (unipolar) or ±5 LSB (bipolar), and the reference input resistance is 10kΩ in normal/STBYPD mode or 4.18MΩ in FULLPD mode.

What is the maximum sampling rate of the MAX1270AENG and what clock frequency is required?

As the MAX1270A variant, the MAX1270AENG achieves a maximum throughput rate of 100ksps in external clock mode. This requires an SCLK frequency of 1.8MHz with 50% duty cycle, as each conversion consumes 18 clock cycles (6 for acquisition + 12 for SAR decisions). In internal clock mode, the device generates its own conversion clock, allowing host MCU SCLK to run at any rate from 0 to 10MHz - though total conversion time remains fixed at ~7.7µs, limiting practical throughput to ~100ksps unless multiple devices are interleaved.