Analog Devices Inc./Maxim Integrated MAX1240BCSA+

Overview

MAX1240BCSA+ from Maxim Integrated is a low-power, 12-bit successive-approximation analog-to-digital converter (ADC) with internal 2.5V reference, 73ksps throughput, and SPI/QSPI/MICROWIRE-compatible 3-wire serial interface. It operates from a single +2.7V to +3.6V supply, consumes only 3.7µW at full speed (VDD = 3V), and features an integrated track/hold with 1.5µs acquisition time - ideal for battery-powered sensor nodes and portable data loggers.

For engineers reviewing the MAX1240BCSA+ datasheet, MAX1240BCSA+ pinout, MAX1240BCSA+ application, or MAX1240BCSA+ equivalent, this page delivers verified electrical specs, package mapping, functional pin roles, real-world use cases, and validated alternative parts - all grounded in the official MAX1240/MAX1241 datasheet (Rev 5, 8/10).

Technical Context

The MAX1240BCSA+ implements a fully integrated SAR architecture with on-chip track/hold and internal clock, eliminating external timing components. Its analog input accepts 0V to VREF (2.5V) signals, and conversion is initiated by CS falling edge, with end-of-conversion signaled by DOUT high transition.

It supports unipolar binary output (MSB-first), requires no external hold capacitor, and uses a 13-cycle serial readout (1 leading EOC bit + 12 data bits). The SHDN pin enables 2µA shutdown mode and controls internal reference activation - high enables 2.5V reference, open disables it for external reference use.

Key Specifications

Pinout & Package

MAX1240BCSA+ is housed in an 8-pin SO (Small Outline) package, RoHS-compliant and lead-free (+ suffix), with 1.27mm pitch and JEDEC MS-012AC outline. Thermal performance supports continuous operation at TA ≤ +70°C with derating above that point.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX1240BCSA+, ADS7822U offers higher throughput but demands external reference and clock generation, increasing design effort and component count; MAX11100ETE+ provides better dynamic performance in a smaller package but shifts reference voltage and requires revalidation of analog front-end gain staging.

Availability

MAX1240BCSA+ is available at Aetrix Electronics and suitable for battery-powered systems, portable data logging, isolated data acquisition, and process control requiring stable component supply across extended production lifecycles.

Supply support for MAX1240BCSA+ 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 semiconductor company specializing in precision analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The MAX1240/MAX1241 family was designed specifically for ultra-low-power, space-constrained data acquisition systems requiring high-resolution conversion without external timing or reference components.

FAQ

What is the maximum sampling rate of the MAX1240BCSA+?

The MAX1240BCSA+ achieves a maximum sampling rate of 73ksps under specified conditions (VDD = +2.7V to +3.6V, fSCLK = 2.1MHz, 50% duty cycle). This corresponds to a 7.5µs conversion time and supports Nyquist-limited signal bandwidth up to ~36.5kHz. At lower throughput rates, power consumption scales down - e.g., 66µW at 1ksps - enabling adaptive sampling strategies in energy-sensitive applications.

Does the MAX1240BCSA+ require an external reference voltage?

No, the MAX1240BCSA+ includes a factory-trimmed 2.5V internal reference. When SHDN is pulled high, the internal reference is enabled and drives the REF pin - requiring only a 4.7µF bypass capacitor. If an external reference is preferred, SHDN can be left open to disable the internal reference, allowing connection of an external VREF (1.0V to VDD) to the REF pin. This dual-reference flexibility is unique to the MAX1240 variant.

What is the function of the SHDN pin on the MAX1240BCSA+?

The SHDN pin on the MAX1240BCSA+ serves three distinct functions: pulling it low activates 2µA shutdown mode; leaving it open disables the internal 2.5V reference (enabling external reference use); and pulling it high enables the internal reference. Unlike simple enable/disable pins, SHDN is a three-state control that directly governs both power state and reference selection - a key differentiator from competing 12-bit ADCs.

Which microcontroller interfaces are compatible with the MAX1240BCSA+ serial port?

The MAX1240BCSA+ 3-wire serial interface is explicitly compatible with SPI, QSPI, and MICROWIRE standards. It operates with CPOL = 0 and CPHA = 0, supports clock rates up to 2.1MHz, and requires only CS, SCLK, and DOUT connections. No protocol translation or bit-banging is needed - standard SPI peripheral modules on ARM Cortex-M, PIC, MSP430, and AVR microcontrollers interface directly with minimal configuration.

What is the absolute maximum input voltage range for AIN on the MAX1240BCSA+?

The absolute maximum AIN voltage on the MAX1240BCSA+ is GND − 0.3V to VDD + 0.3V per Absolute Maximum Ratings. However, for guaranteed 12-bit accuracy and linearity, the functional input range is strictly 0V to VREF (2.5V) when using the internal reference. Exceeding VREF by more than 50mV or dropping below GND by more than 50mV degrades DC accuracy and may trigger internal protection diodes - limiting input current to 2mA if overvoltage occurs.