Analog Devices Inc./Maxim Integrated MAX1241ACSA+

Overview

MAX1241ACSA+ from Maxim Integrated is a low-power, 12-bit successive-approximation analog-to-digital converter (ADC) with 73ksps throughput, 7.5µs conversion time, and SPI/QSPI/MICROWIRE-compatible 3-wire serial interface. It operates from a single +2.7V to +5.25V supply, requires an external reference (0V to VREF input range), and targets space-constrained, battery-powered data acquisition systems.

For engineers reviewing the MAX1241ACSA+ datasheet, MAX1241ACSA+ pinout, MAX1241ACSA+ application, or MAX1241ACSA+ equivalent, key selection criteria include its external-reference dependency, 8-pin SO package footprint, 1.5µs track/hold acquisition time, ±0.5 LSB INL at +25°C, and shutdown current of ≤2µA - all critical for precision, low-quiescent remote sensing designs.

Technical Context

The MAX1241ACSA+ implements a capacitive SAR architecture with integrated track/hold, eliminating need for external hold capacitors. Its conversion cycle begins on CS falling edge, uses internal clocking, and outputs unipolar 12-bit data with leading EOC bit via DOUT on SCLK falling edges.

It supports flexible reference configurations: accepts external VREF from 1.0V to VDD with ≤10Ω source impedance and ≥18kΩ DC input resistance; REF pin must be bypassed with ≥0.1µF capacitor. SHDN enables 2µA shutdown mode and controls internal reference enablement only in MAX1240 variants - irrelevant here since MAX1241ACSA+ lacks internal reference.

Key Specifications

Pinout & Package

MAX1241ACSA+ is housed in an 8-pin SO (Small Outline) package, RoHS-compliant and lead-free (+ suffix), with standard JEDEC MS-012AC dimensions (4.9mm × 3.9mm, 1.75mm height, 1.27mm pitch).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS7822U and AD7476AARMZ, MAX1241ACSA+ uniquely balances low shutdown current (≤2µA), external reference support for system-level voltage scaling, and proven 73ksps precision in 8-pin SO - making it optimal for battery longevity and reference architecture flexibility in portable industrial sensors.

Availability

MAX1241ACSA+ is available at Aetrix Electronics and suitable for battery-powered data loggers, isolated sensor interfaces, portable medical instrumentation, and process control transmitters requiring stable component supply across extended production lifecycles.

Supply support for MAX1241ACSA+ 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) designs precision analog and mixed-signal ICs for industrial, medical, and communications applications.

The MAX1240/MAX1241 product line delivers low-power, high-accuracy 12-bit ADCs optimized for remote, space-constrained, and battery-operated data acquisition systems requiring minimal external components.

FAQ

What is the reference voltage configuration for MAX1241ACSA+?

MAX1241ACSA+ requires an external reference applied to the REF pin, supporting 1.0V to VDD. It does not include an internal reference - unlike the MAX1240 family. The REF pin must be bypassed with ≥0.1µF capacitor, and the reference source must provide ≤10Ω output impedance and sustain up to 250µA load during conversion. MAX1241ACSA+ achieves ±0.5 LSB INL using such externally sourced references.

Does MAX1241ACSA+ support SPI, QSPI, and MICROWIRE protocols simultaneously?

Yes, MAX1241ACSA+ is electrically and timing-compatible with SPI, QSPI, and MICROWIRE standards. It uses CPOL = 0 and CPHA = 0 mode, outputs data on SCLK falling edge, and accepts CS falling edge as conversion trigger. For QSPI, it delivers all 12 bits in 13 clock cycles without trailing zeros; for SPI/MICROWIRE, two byte reads (with leading EOC bit and trailing zeros) are typical. MAX1241ACSA+ requires no mode pins or configuration registers to enable protocol compatibility.

What is the minimum acquisition time between conversions for MAX1241ACSA+?

The minimum acquisition time for MAX1241ACSA+ is 1.5µs - this is both the maximum time required to acquire the input signal and the minimum interval needed before initiating the next conversion. This value assumes source impedance ≤1kΩ. Higher impedances increase tACQ per tACQ = 9(RS + 9kΩ) × 16pF, requiring longer inter-conversion delays to maintain accuracy. MAX1241ACSA+ does not require external hold capacitors regardless of source impedance.

Can MAX1241ACSA+ operate from a 5V supply while using a 2.5V external reference?

Yes, MAX1241ACSA+ supports VDD = +5.25V and VREF = +2.5V simultaneously. Its REF input range includes the positive supply rail, and it accepts any stable external reference from 1.0V to VDD. When using 2.5V reference with 5V supply, full-scale input remains 0V to 2.5V, and the device maintains ±0.5 LSB INL and 70dB SINAD performance. The 2.5V reference must be bypassed with ≥0.1µF capacitor and capable of sourcing 250µA during conversion.

How does shutdown mode function on MAX1241ACSA+?

Shutdown mode on MAX1241ACSA+ is activated by pulling the SHDN pin low, reducing supply current to ≤2µA. In shutdown, the internal analog circuitry (including track/hold and SAR core) is disabled, but digital inputs remain functional. Wake-up time is 4µs after SHDN is deasserted, enabling rapid resumption of conversion. Unlike MAX1240, SHDN has no effect on reference selection in MAX1241ACSA+ - the device always relies on external reference regardless of SHDN state.