Analog Devices Inc./Maxim Integrated MAX1240ACSA

Overview

MAX1240ACSA from Maxim Integrated is a low-power, 12-bit successive-approximation analog-to-digital converter (ADC) with internal 2.5V reference, 73ksps throughput, 7.5µs conversion time, and SPI/QSPI/MICROWIRE-compatible 3-wire serial interface - designed for precision data acquisition in space-constrained, battery-powered sensor nodes.

For engineers reviewing the MAX1240ACSA datasheet, MAX1240ACSA pinout, MAX1240ACSA application, or MAX1240ACSA equivalent, this page delivers verified electrical specs, package mapping to 8-pin SO, functional pin roles, real-world use cases in isolated instrumentation and portable logging, and two validated alternative ADCs with documented differences in reference architecture and supply range.

Technical Context

The MAX1240ACSA integrates a track/hold amplifier with 1.5µs acquisition time and a 12-bit SAR core clocked by an on-chip oscillator. Its unipolar transfer function maps 0V–VREF input to 0x000–0xFFF output codes, with VREF sourced internally at 2.500V ±0.5 LSB INL over 0°C to +70°C.

Control logic responds to active-low CS falling edge to initiate conversion, outputs end-of-conversion (EOC) via DOUT high transition, and shifts out MSB-first serial data synchronized to SCLK falling edges - supporting direct connection to microcontroller GPIO without level-shifting or external timing components.

Key Specifications

Pinout & Package

MAX1240ACSA is housed in an 8-pin SO (Small Outline) package with gull-wing leads, JEDEC MS-012AC compliant, 150 mil body width, and RoHS-compliant lead finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX1240ACSA, ADS7822U trades integrated reference simplicity for higher speed and wider supply range, while MAX11100ASA+ offers faster conversion and higher reference voltage at the cost of different pinout and package size - making MAX1240ACSA optimal for cost-sensitive, space-constrained, single-supply 2.5V-range applications.

Availability

MAX1240ACSA is available at Aetrix Electronics and suitable for battery-powered systems, portable data logging, isolated data acquisition, and process control applications requiring stable component supply across extended production lifecycles.

Supply support for MAX1240ACSA 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, mixed-signal, and power management ICs for industrial, medical, and communications systems - emphasizing low power, small size, and high reliability.

The MAX1240 family targets ultra-low-power, high-accuracy data acquisition in resource-constrained environments - delivering 12-bit resolution with integrated reference and serial interface in minimal 8-pin SO packaging.

FAQ

What is the reference voltage configuration of the MAX1240ACSA?

The MAX1240ACSA features a factory-trimmed internal 2.500V reference, accessible at the REF pin and used to set the full-scale input range (0V to 2.500V). It is enabled when SHDN is pulled high, disabled when SHDN is left floating, and bypassed with a 4.7µF capacitor for stability. This eliminates external reference components in most designs using the MAX1240ACSA.

Does the MAX1240ACSA require an external clock to perform conversion?

No - the MAX1240ACSA contains an internal clock generator that handles the 7.5µs conversion cycle autonomously. The external SCLK is used only for serial data readout after conversion completes. This allows flexible timing: the host MCU can initiate conversion via CS and read results at its convenience, decoupling sampling rate from data transfer timing in the MAX1240ACSA.

What is the maximum sampling rate supported by the MAX1240ACSA?

The MAX1240ACSA achieves a maximum throughput rate of 73ksps under specified conditions (VDD = 3V, fSCLK = 2.1MHz, TA = 0°C to +70°C). This corresponds to a minimum conversion period of 13.7µs including acquisition and serial readout. At lower rates, power consumption scales down - e.g., 66µW at 1ksps - making the MAX1240ACSA highly adaptable to variable-speed sensing tasks.

How does the SHDN pin function on the MAX1240ACSA?

The SHDN pin on the MAX1240ACSA provides three distinct modes: pulled high → enables internal 2.5V reference; left open → disables internal reference for external reference use; pulled low → activates 2µA shutdown mode. In shutdown, the MAX1240ACSA retains all bias states and wakes up in <4µs (with external reference) or <20ms (with internal reference charging), enabling rapid duty-cycled operation.

Is the MAX1240ACSA compatible with standard microcontroller serial interfaces?

Yes - the MAX1240ACSA's 3-wire serial interface is fully compatible with SPI, QSPI, and MICROWIRE protocols. It operates with CPOL = 0 and CPHA = 0, outputs MSB-first data on DOUT synchronized to SCLK falling edges, and uses CS falling edge to trigger conversion. No level shifters or protocol translation are needed when interfacing the MAX1240ACSA with common ARM Cortex-M or PIC microcontrollers.